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Research Article
North-Western Palaearctic species of the Pristiphora ruficornis group (Hymenoptera, Tenthredinidae)
expand article infoMarko Prous, Veli Vikberg§, Andrew David Liston|, Katja Kramp|
‡ Senckenberg Deutsches Entomologisches Institut (Müncheberg, Germany) and University of Tartu, Tartu, Finland
§ Unaffiliated, Turenki, Finland
| Senckenberg Deutsches Entomologisches Institut, Müncheberg, Germany
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Abstract

The Pristiphora ruficornis group, defined here based on the structure of the penis valve and the genetic data, includes morphologically and genetically highly similar species that remain taxonomically challenging. Study of most of the relevant type material, examination of female saws and male genitalia, some rearing experiments, and genetic data enabled us to solve most of the taxonomic problems involving northern European taxa. As a result, 17 species are recognised in northern Europe. The following synonymies are proposed: Pristiphora aterrima Lindqvist, 1977, syn. n. is synonymised with P. albitibia (Costa, 1859), P. brunniapex Lindqvist, 1960, syn. n. and P. coniceps Lindqvist, 1955, syn. n. both with P. subopaca Lindqvist, 1955, Nematus vitreipennis Eversmann in Kawall, 1864, syn. n. (nomen oblitum) with P. leucopus (Hellén, 1948) (nomen protectum), and Nematus (Pristiphora) ruficornis var. integer Hellén, 1948, syn. n. with P. ruficornis (Olivier, 1811). Lectotypes are designated for the following taxa: Nematus appendiculatus Hartig, 1837, Nematus cathoraticus Förster, 1854, Nematus (Pristiphora) bifidus Hellén, 1948, Nematus frigidus Boheman, 1865, Pristiphora adelungi Konow, 1902, Nematus vitreipennis Eversmann in Kawall, 1864, Nematus melanocarpus Hartig, 1840, Nematus wuestneii Stein, 1885, Pristiphora pusilla Malaise, 1921, and Nematus fraxini Hartig, 1837. An illustrated electronic key made with Lucid and a traditional dichotomous key are provided to facilitate identification of the species. In addition we report the first occurrence of distinctly asymmetrical penis valves in Pristiphora (in P. pusilla), a condition rarely observed in Hymenoptera.

Keywords

Sawflies, lectotypes, new synonyms, nomenclature, taxonomy, identification key, phylogeny, asymmetrical genitalia, triose-phosphate isomerase, cytochrome oxidase subunit I, DNA barcoding

Introduction

Pristiphora Latreille, 1810 contains several species groups, within which identification of species is difficult because of high similarity in external morphology, the need to study female saws and male genitalia, and the lack of reliable keys and recent revisions (Lindqvist 1952; 1953; 1955; Benson 1958; Lindqvist 1962; Zhelochovtsev [and Zinovjev] 1988). One of the species groups is the ruficornis or melanocarpa group (Lindqvist 1955), within which species are externally very similar, although males generally show good differences in genitalia (penis valves). Based on genetic data and penis valves, we delimit this group more precisely and call it the ruficornis group (based on the oldest species name within the group: ruficornis Olivier in Olivier & Manuel, 1811). Studies by Vikberg (1978; 2006) solved some of the problems within the group, but many gaps and deficits remain, such as the validity of many nominal species, association of males and females, and the lack of reliable keys to identify species. Here, we revise the group in northern Europe, recognising 17 species as valid. An illustrated electronic key (Lucid) and a traditional dichotomous key are provided together with high resolution photos of female lancets and male penis valves to enable identification of species more reliably than previously.

The host plant associations, details of larval morphology, and bionomy of only a few species of the ruficornis group have been recorded in detail. Because its larvae sometimes defoliate cultivated Ribes, particularly R. uva-crispa (gooseberry), biological observations on P. appendiculata are included in numerous publications, including many general and popular works on plant “pests” (e.g. Meitzner 1985; Alford 2014). As a result of its status as a “pest”, this is the only species in the ruficornis group that has vernacular names in several languages, such as “small gooseberry sawfly” in English, and “Schwarzen Stachelbeerblattwespe” in German. This species is normally thelytokous, with very rare males (Comrie 1938). Males of several other species of the ruficornis group are unknown or very rare (P. aphantoneura, P. astragali, populations of P. luteipes in northern and middle Europe, and P. sootryeni: Vikberg 1978; 2006), or occur at a low ratio (e.g. P. leucopus: Grearson and Liston 2012), whereas the sex ratio of others appears to be about normal. Voltinism differs between species, and probably also according to climate. The group shows a broad spectrum of phenological patterns: particularly the boreo-alpine species, e.g. P. staudingeri, are probably univoltine, based on collection dates of adults, while others are apparently bivoltine (e.g. P. bifida: Liston and Burger 2009), or plurivoltine, with four generations per year, or even more in optimal conditions (e.g. P. appendiculata, P. leucopus: Miles 1932, Grearson and Liston 2012). So far unique in the species group, and a rare phenomenon in the Tenthredinidae, is the seasonal dimorphism detected in adult P. leucopus (Grearson and Liston 2012). In all species, as far as observations have been made: oviposition is in the leaf-blade margin (Vikberg 2006, Grearson and Liston 2012), in P. appendiculata also infrequently in the interior, near a vein (Miles 1932); only one egg is laid per leaf, and the larvae are normally solitary, feeding from the leaf-edge (Grearson and Liston 2012, Meitzner 1985, personal observations on P. bifida). Exceptionally, more eggs are laid per leaf at high population levels in P. appendiculata, but density of larvae is probably regulated by egg cannabilism: Rahoo and Luff 1988). There are four or five larval instars and no prepupal ecdysis (“extra moult”) (Miles 1932, Vikberg 2006). Cocoons of the overwintering generation are made in the soil, but those of some the summer generations may be made above ground, often between leaves or on the underside of leaves (Miles 1932, Grearson and Liston 2012).

Larvae are cryptically coloured, with a largely green body (https://doi.org/10.6084/m9.figshare.3486341.v1). Only the head and coxae of the thoracic legs are more or less dark-marked. The dark pattern on the head of the final instar larva, composed of spots of brown pigment that to the naked eye appear confluent and blackish, is similar in all species of the ruficornis group: a stripe along the coronal suture, branching ventrally to run along upper edges of frons; upper frons more or less dark marked; an approximately vertical stripe on each orbit that does not connect with the coronal stripe. The anal tergum of the abdomen is entirely green in some species of the group of which the larva is known, but yellow in P. appendiculata, and extensively red in P. aphantoneura, P. luteipes, P. sootryeni (Vikberg 2006), P. staudingeri (Vikberg 1978) and possibly P. armata (Lorenz and Kraus 1957: who wrote under the name P. ruficornis that larvae, which they collected from Crataegus and were presumably therefore P. armata, had an extensive red patch on the dorsum of the last abdominal segment). Differences in setation can apparently be used to distinguish the larvae of some species, according to the descriptions in Lorenz and Kraus (1957) and Vikberg (2006), but detailed descriptions of many species are lacking. It is not clear to which species the description of P. melanocarpa by Lorenz and Kraus (1957) belongs: according to the list of host plants (Pflanzenliste) they examined larvae collected from both Betula and Salix cinerea. Because detailed studies on immature stages of most species are still lacking, we only summarize and complement data on host plants of the ruficornis group species.

Material and methods

Specimens examined or mentioned are deposited in the following collections:

ANSP Academy of Natural Sciences of Drexel University, Philadelphia, USA

BMNH The Natural History Museum, London, United Kingdom

CEH Collection of Erik Heibo, Lierskogen, Norway

COL Collection of Ole Lønnve, Oslo, Norway

CVV Collection of Veli Vikberg, Turenki, Finland

HNHM Hungarian Natural History Museum, Budapest, Hungary

IRSNB Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium

MCZ Museum of Comparative Zoology, Cambridge, USA

MHNG Muséum d’Histoire Naturelle, Geneva, Switzerland

MNHN Muséum National d’Histoire Naturelle, Paris, France

MZH Finnish Museum of Natural History, Helsinki, Finland

MZLU Lunds universitet, Lund, Sweden

MZUN Museo Zoologico di Università degli Studi, Napoli, Italy

NHRS Naturhistoriska riksmuseet, Stockholm, Sweden

NMW Naturhistorisches Museum Wien, Wien, Austria

SDEI Senckenberg Deutsches Entomologisches Institut, Müncheberg, Germany

SMTP Swedish Malaise Trap Project, Station Linné, Öland, Sweden

TROM Tromsø UniversityMuseum, Tromsø, Norway

TUZ Natural History Museum, University of Tartu, Tartu, Estonia

USNM National Museum of Natural History, Washington D.C., USA

ZIN Russian Academy of Sciences, Zoological Institute, St. Petersburg, Russia

ZSM Zoologische Staatssammlung, München, Germany

Names of the mentioned host plants follow The Plant List (http://www.theplantlist.org/).

Collecting data of the examined specimens is included in an excel file available at Dryad Digital Repository: https://doi.org/10.5061/dryad.tj4t0

Morphological methods

To photograph penis valves and lancets (valvula 1 or ventral part of saw), genital capsules and ovipositors were separated from the specimen and macerated in KOH (10–15%) for 6–10 hours at room temperature or treated with proteinase during DNA extraction (see below). Temporary or permanent slide preparations were made of dissected lancets and penis valves. For temporary slides, glycerine was used. After photographing, the lancets and penis valves were glued on a piece of cardboard, which was pinned with the corresponding specimen. For permanent slides, Euparal or PVA-mounting medium (mostly) was used (these specimens are labelled as ‘PR.XXXVV’, e.g. PR.440VV). PVA-mounting medium (Danielsson 1985) is water-soluble, is simpler to use than Euparal (no alcohol needed), and mounts remain in good quality for 30 or more years.

Photos were taken with a digital camera attached to a microscope. Composite images with an extended depth of field were created from stacks of images using the software CombineZP (Alan Hadley; http://www.hadleyweb.pwp.blueyonder.co.uk/). Most of the lancets were photographed in two overlapping parts and a single image was created using the program Image Composite Editor (Microsoft).

Morphological terminology follows Vikberg (1978; 2006) and Viitasaari (2002).

Molecular methods

DNA was extracted and purified with an EZNA Tissue DNA Kit (Omega Bio-tek) according to the manufacturer’s protocol and stored at -20 °C for later use. Typically, the middle right leg was used for DNA extraction, but for males the whole genital capsule was often additionally used to increase DNA yield and to free penis valves from muscles for photographing. One mitochondrial and one nuclear region were used in phylogenetic analyses. Primers used for amplification and sequencing are listed in Table 1. The mitochondrial region used is a large fragment (1078 bp) of cytochrome oxidase subunit I gene (COI). The first (from the 5' end) 658 bp of this fragment correspond to the standard barcode region of the animal kingdom (Hebert et al. 2003). If the amplification of the 1078 bp fragment failed, or was expected to fail because of low DNA quality, the region was amplified in two overlapping fragments, or only the barcoding (658 bp) region was obtained (Table 1). The nuclear marker used is nearly the complete gene of triose-phosphate isomerase (TPI), containing 661 bp or 676 bp (depending on the primers used for amplification) of three exons and two short introns (around 50–100 bp) in Nematinae (Table 1), altogether around 800–830 bp. New COI primers were designed based on a broad sample of sawfly COI sequences available in NCBI GenBank (http://www.ncbi.nlm.nih.gov/genbank/) or BOLD (http://www.boldsystems.org/), plus a few unpublished full COI sequences. New TPI primers were designed mainly based on four sawfly genomes and one transcriptome available in GenBank (accessions AOFN01004053, GAWW01005368, LGIB01000103, AMWH01006520, AZGP01000520) or using sequences published by Malm and Nyman (2015). Numbers in the new TPI primer names refer to the binding position of the primer’s 3' end in the coding region of Athalia rosae mRNA (accession XM_012402337).

Primers used for PCR and sequencing, with information provided on respective gene fragment, primer name, direction (forward, F or reverse, R) and location (internal, i or external, o) according to each gene fragment, primer sequence, standard annealing temperature, utilization (PCR/ sequencing), and reference.

Gene Region Primer name F/R i/o Primer sequence 5'–3' Annealing temperature (°) PCR/Sequencing Reference
COI SymF1 F o TTTCAACWAATCATAAARAYATTGG 47 PCR, seq This study
COI SymF2 F o TTTCAACAAATCATAAARAYATTGG 47 PCR, seq This study
COI sym- C1-J1718 F i/o GGAGGATTTGGAAAYTGAYTAGTWCC 49 PCR, seq (Nyman et al. 2006)
COI symC1- J1751 F i/o GGAGCNCCTGATATAGCWTTYCC 47 PCR, seq This study
COI C1-N1760 R i/o GGTARAAATCARAATCTTATATTAT 47 PCR, seq (Prous et al. 2011)
COI SymR1 R i/o TAAACTTCWGGRTGICCAAARAATC 47 PCR, seq This study
COI SymR2 R i/o TAAACTTCTGGRTGTCCAAARAATCA 47 PCR, seq This study
COI A2590 R o GCTCCTATTGATARWACATARTGRAAATG 49 PCR, seq (Normark et al. 1999)
TPI TPI_29Fi F o GYAAATTYTTYGTTGGNGGIAA 52 PCR, seq This study
TPI TPI 111Fb F o GGNAAYTGGAARATGAAYGG 56 PCR, seq (Bertone et al. 2008)
TPI TPI hym intF F i AARGGHGCNTTYACYGGNGA 56 Seq (Malm and Nyman 2015)
TPI TPI hym intR R i TCNGARTGDCCHADRATNACCCA 52 Seq (Malm and Nyman 2015)
TPI TPI385Fi F o GTRATYGCNTGYATYGGIGARA 52 PCR, seq This study
TPI TPI 275Ri R o GCCCANACNGGYTCRTAIGC 56 PCR, seq (Malm and Nyman 2015)
TPI TPI706R R o ACNATYTGTACRAARTCWGGYTT 52 PCR, seq This study

PCR reactions were carried out in a total volume of 15–20 µl containing 1–2 µl of extracted DNA, 0.6–0.8 µl (3–4 pmol) of primers and 7.5–10 µl of 2x Multiplex PCR Plus Master mix (QIAGEN). The PCR protocol consisted of an initial DNA polymerase (HotStar Taq) activation step at 95 °C for 5 min, followed by 38–40 cycles of 30 s at 95 °C, 90 s at 47–56 °C depending on the primer set used, and 30–70 s (depending on the amplicon size) at 72 °C; the last cycle was followed by a final 30 min extension step at 68 °C. 3 µl of PCR product was visualised on a 1.4% agarose gel and then purified with FastAP and Exonuclease I (Thermo Scientific). 1.0–1.5 U of both enzymes were added to 12–17 µl of PCR solution and incubated for 15 min at 37 °C, followed by 15 min at 85 °C. Purified PCR products were sent to Macrogen (Netherlands) for sequencing. To obtain unequivocal sequences, both sense and antisense strands were sequenced, using the primers listed in Table 1. Ambiguous positions (i.e. double peaks in chromatograms of both strands) due to heterozygosity or intragenomic variation were coded using IUPAC symbols.

Sequences reported here have been deposited in the GenBank (NCBI) database (accession numbers KX602529KX602627).

COI sequences were aligned manually, among which only some specimens of Pristiphora appendiculata showed differences in length caused by deletion of six base pairs (two amino acids). The exact position of this deletion was located by translating nucleotides into amino acids (using the invertebrate mitochondrial genetic code). The TPI sequences including introns of ruficornis group specimens were aligned using MAFFT 7 (Katoh and Standley 2013) online version (http://mafft.cbrc.jp/alignment/server/) with the thorough iterative alignment strategy G-INS-i. Because of problems identifying homologous positions within introns between ruficornis-group and outgroup species, introns were excluded for all outgroup species and exons were aligned manually, which was straightforward because there were no insertions or deletions.

Sequence data were analysed using the maximum likelihood method (ML) with PhyML 3.0.1 (http://www.atgc-montpellier.fr/phyml/; Guindon and Gascuel 2003). In PhyML nearest neighbor interchanges (NNI) and subtree pruning and regrafting (SPR) were always used to estimate tree topologies (i.e. using the extensive tree search option). Robustness of reconstructed trees was estimated with 1000 bootstrap replicates and approximate likelihood-ratio test (aLRT) implemented in PhyML (Anisimova and Gascuel 2006). Prior to analyses using maximum likelihood, duplicate sequences were removed to save computation time. General Time Reversible model of nucleotide substitution under discrete Gamma model of rate heterogeneity among sites with four rate categories (GTR+G4) was used to calculate maximum likelihood trees. Estimation of proportion of invariable sites as commonly used in phylogenetic likelihood analyses was not applied, because the Gamma model already allows for sites that evolve very slowly (i.e. are effectively invariable). As described in the RAxML manual, combining Gamma model and proportion of invariable sites (G+I) is problematic for parameter estimation as they are interdependent (http://sco.h-its.org/exelixis/resource/download/NewManual.pdf). Alignment files and tree files from the PhyML analyses are available at Dryad Digital Repository (https://doi.org/10.5061/dryad.tj4t0).

Some of the COI barcode sequences used here were obtained from BOLD (http://www.boldsystems.org/). In this case, DNA extraction, PCR amplification, and sequencing were conducted at the Canadian Centre for DNA Barcoding (CCDB) in Guelph, Canada using standardised high-throughput protocols (Ivanova et al. 2006; deWaard et al. 2008), available online under www.ccdb.ca/resources.php. DNA aliquots of SDEI vouchers are deposited in the DNA storage facility of the SDEI (including those that were originally extracted in CCDB).

Barcode distance calculations were based on p-distances (proportion of nucleotide differences) and were taken from the BOLD BIN (Barcode Index Number) database (http://www.boldsystems.org/).

Preparation of the keys

The electronic identification key for the species of ruficornis-group was prepared in Lucid 3.5 Builder (http://www.lucidcentral.org/) and a zip file containing all the Lucid data files is available at Dryad Digital Repository (https://doi.org/10.5061/dryad.tj4t0). If the licence for Lucid 3.5 is lacking, the free version of Lucid 3.3 can be used to run the key. Only species of the ruficornis group are included in the key, but there are additional characters that do not vary within the group, but which can be used to exclude other Pristiphora species. In case of ambiguities or polymorphisms in character states, we conservatively coded these to multiple states. The key contains 37 morphological features with 94 character states and 43 entities (species and groups, 20 for males and 23 for females). The first choice given in the key is between female and male, one of which has to be chosen to see all other characters. After that, characters can be chosen freely or one can use ‘Best’ and ‘Next Best’ tools in Lucid that suggests the most efficient sequence of characters for identification.

A traditional dichotomous key was constructed manually to emphasise the most reliable characters (usually penis valves or lancets).

Results

Definition of the Pristiphora ruficornis group and its separation from other Pristiphora species

Phylogenetic analyses of mitochondrial COI sequences (Fig. 1) identify a strongly supported clade within Pristiphora, that is morphologically best characterised by male penis valves, which have a large and bent (often strongly) ventro-apical spine (Figs 77103). When ignoring the species that are missing from our nuclear TPI dataset, the same clade is recovered with strong support also based on this gene (Fig. 2). Here, we call this clade the Pristiphora ruficornis group (=melanocarpa group). Externally there are no characters to unambiguously unite all species within this group to the exclusion of all other Pristiphora species. Females have a typical Pristiphora-type sawsheath (Figs 3–4) with large scopa, and the body is completely black (Figs 9, 11) in nearly all species (except P. beaumonti and some specimens of P. subopaca; Figs 9, 12–13). Bodies of males are also nearly always completely black (except some specimens of P. beaumonti). The short post-ocellar area (Fig. 5) helps to distinguish the ruficornis group from some completely black species [e.g. P. geniculata (Hartig, 1840), P. pseudogeniculata Lindqvist, 1969, some specimens in rufipes group] with long post-ocellar area (Fig. 6), although this character might not be reliable for males. Very similar to the ruficornis group are species in the rufipes group (=thalictri group). Generally the species in the rufipes group have a rather smooth mesopostnotum compared to most species in ruficornis group, except P. appendiculata, which has a completely smooth mesopostnotum (Fig. 7). However, P. appendiculata has simple claws, while species of the rufipes group have a small subapical tooth. The only reliable way to separate the rufipes and ruficornis groups is by studying lancets and penis valves. Female lancets lack ctenidia entirely in the rufipes group (Fig. 40), while there are weakly or well-developed ctenidia present on at least some annulets of the lancet in most species of ruficornis-group (e.g. Fig. 39). Unfortunately, if the ctenidia are weakly developed, they might not be visible without making a slide preparation and studying the lancet under a microscope using phase contrast. The Betula-feeding Pristiphora melanocarpa and P. ruficornis practically lack ctenidia, but their lancets have a distinctly shaped tangium (Figs 4653), usually visible without dissecting the saw (Fig. 14), which separates these two species from other Pristiphora. Pristiphora appendiculata also lacks or almost lacks ctenidia (Figs 37–38), but the shape of the serrulae distinguishes it from species in the rufipes group (Fig. 40). Identification based on male penis valves is easier, because many distinct characteristics enable their separation from each other (usually) and from other species of Pristiphora that are similar in colouration to the ruficornis group (Figs 77104). A separate electronic key is provided to separate species of the ruficornis group from each other and from other Pristiphora species.

Figure 1.

Maximum likelihood tree of Pristiphora ruficornis group based on cytochrome oxidase subunit I(COI) sequences (1078 bp). Specimens that had at least the full barcode sequence (658 bp) were included in the analysis. Branches with multiple specimen identification labels represent identical sequences, only one of which was used in the analysis. Numbers on the nodes show approximate likelihood-ratio test (aLRT) support values and bootstrap proportions (%, BP). Support values for weakly supported branches (aLRT<0.9 and/or BP<70) are not shown. The inset shows the tree with outgroup species. The scale bar shows the number of estimated substitutions per nucleotide position. An asterisk (*) indicates the specimens that we have not studied. AUT, Austria; CAN, Canada; CHN, China; DEU, Germany; ESP, Spain; EST, Estonia; FIN, Finland; FRA, France; GBR, United Kingdom; ITA, Italy; MAR, Morocco; NOR, Norway; PRT, Portugal; SWE, Sweden; USA, United States of America. NUMTs?, possible nuclear mitochondrial pseudogenes.

Figure 2.

Maximum likelihood tree of Pristiphora ruficornis group based on triose-phosphate isomerase (TPI) sequences (alignment length 842 bp). Branches with multiple specimen identification labels represent identical sequences, only one of which was used in the analysis. Numbers on the nodes show approximate likelihood-ratio test (aLRT) support values and bootstrap proportions (%, BP). Support values for weakly supported branches (aLRT<0.9 and/or BP<70) are not shown. The scale bar shows the number of estimated substitutions per nucleotide position.

Figures 3–17.

3 Pristiphora bifida DEI-GISHym31507, sawsheath with large scopa (arrows) in dorsal view 4 P. appendiculata DEI-GISHym80025, sawsheath with large scopa (arrows) in apical view 5 P. albitibia DEI-GISHym31514, head in dorsal view showing short postocellar area (lines and arrows) 6 P. geniculata DEI-GISHym20961, head in dorsal view showing long postocellar area (lines and arrows) 7 P. appendiculata DEI-GISHym31500, smooth mesopostnotum (arrow) 8 P. albitibia DEI-GISHym31516, matt mesopostnotum (arrow) 9 P. ruficornis DEI-GISHym31185, dorsal view 10 P. subopaca DEI-GISHym20899, dorsal view 11 P. ruficornis DEI-GISHym31185, lateral view 12 P. subopaca DEI-GISHym20899, lateral view 13 P. beaumonti DEI-GISHym20766, lateral view 14 P. melanocarpa DEI-GISHym21031, abdomen in lateral view 15 P. luteipes DEI-GISHym18872, abdomen in lateral view 16 P. armata DEI-GISHym11092, tergum 8 in dorsal view with apical projection (arrow) 17 P. subopaca DEI-GISHym31560, tergum 8 in dorsal view without apical projection.

Figures 18–36.

18 P. albitibia DEI-GISHym31514, thorax in lateral view 19 P. luteipes DEI-GISHym80038, thorax in lateral view 20 P. astragali holotype, thorax in lateral view 21 P. leucopus DEI-GISHym31556, lateral 22 P. leucopus DEI-GISHym4989, lateral 23 P. luteipes DEI-GISHym80038, lateral 24 P. luteipes DEI-GISHym80038, flagellum 25 P. ruficornis DEI-GISHym31185, flagellum 26 P. armata DEI-GISHym11092 27 P. subopaca holotype, pterostigma (arrow) 28 P. opaca holotype, pterostigma (arrow) 29 P. ruficornis DEI-GISHym31185, pterostigma (arrow) 30 P. appendiculata DEI-GISHym31500, claw 31 P. opaca holotype, claw 32 P. subopaca holotype, claw 33 P. armata DEI-GISHym11554, claw 34 P. bifida DEI-GISHym31507, claw 35 P. frigida NHRS-HEVA000005006, flagellum with barely visible stout black setae (arrows) 36 P. pusilla DEI-GISHym80050, flagellum with clearly visible stout black setae.

Figures 37–40.

Lancets of Pristiphora appendiculata subgroup and P. rufipes. 37 P. appendiculata DEI-GISHym17852 38 P. appendiculata DEI-GISHym21073 39 P. ribisi DEI-GISHym17879 40 P. rufipes DEI-GISHym31537.

Figures 41–45.

Lancets of Pristiphora albitibia subgroup. 41 P. albitibia DEI-GISHym20944 42 P. aterrima holotype 43 P. astragali DEI-GISHym80042 44 P. astragali PR.365VV 45 P. sootryeni PR.366VV.

Figures 46–49.

Lancets of P. melanocarpa showing variation in the shape of the tangium. Some of the specimens have rather distinct small outgrowth between tangium and laminum (arrow in Fig. 49). 46 PR.436VV reared ex larva from Betula pubescens 47 PR.423VV reared ex larva from Betula pubescens 48 PR.434VV 49 PR.431VV, several larvae were reared ex ovo from this female ovipositing in the leaves of Betula nana.

Figures 50–53.

Lancets of P. melanocarpa and P. ruficornis showing variation in the shape of the tangium. Lancets shown here clearly lack small outgrowth between tangium and laminum, which can be seen at least in Figs 48–49 50 P. melanocarpa PR.440VV 51 P. melanocarpa PR.407VV 52 P. ruficornis PR.479VV 53 P. melanocarpa PR.723VV reared ex larva from Betula pendula.

Figures 54–57.

Lancets of Pristiphora armata subgroup. 54 P. leucopus PR.393VV, summer morph 55 P. leucopus PR.467VV reared ex larva from Tilia sp. 56 Nematus armatus Thomson syntype specimen 8 (X112) 57 P. armata DEI-GISHym20366.

Figures 58–61.

Lancets of Pristiphora aphantoneura subgroup. 58 P. aphantoneura holotype 59 P. aphantoneura PR.695VV reared from Lathyrus pratensis 60 P. luteipes PR.696VV reared from Salix phylicifolia 61 P. beaumonti DEI-GISHym20927.

Figures 62–65.

Lancets of Pristiphora aphantoneura subgroup. 62 P. confusa holotype 63 P. confusa PR.544VV reared ex larva from Salix caprea 64 P. opaca DEI-GISHym80032 (presence of a fold is indicated by an arrow) 65 P. opaca PR.389VV.

Figures 66–69.

Lancets of Pristiphora subopaca. 66 PR.403VV 67 P. subopaca holotype 68 P. coniceps holotype 69 P. brunniapex holotype.

Figures 70–72.

Lancets of Pristiphora aphantoneura subgroup and P. frigida. 70 P. bifida PR.408VV 71 P. frigida NHRS-HEVA000003873 72 P. pusilla PR.369VV.

Figures 73–76.

Lancets of Pristiphora staudingeri showing variation in the number of ctenidia. 73 PR.441VV with ctenidia on annulets (3)4–12(13) 74 PR.402VV with ctenidia on annulets 3–13 75 PR.373VV with ctenidia on annulets 3–14 76 PR.457VV with ctenidia on annulets (2)3–15.

Figures 77–86.

Penis valves of Pristiphora ruficornis group. 77 P. appendiculata DEI-GISHym31555 78 P. albitibia DEI-GISHym20956 79 P. ruficornis PR.462VV 80 P. melanocarpa PR.425VV 81 P. ruficornis DEI-GISHym19636 82 P. melanocarpa PR.409VV 83 P. armata PR.465VV 84 P. leucopus PR.466VV reared ex ovo from Tilia sp. 85 P. armata DEI-GISHym80020 86 P. leucopus GBIF-GISHym3246 (syntype of Nematus crassicornis Hartig).

Figures 87–96.

Penis valves of Pristiphora ruficornis group. 87 P. bifida DEI-GISHym80000 (arrow indicates a dorsal depression of the pseudoceps) 88 P. frigida NHRS-HEVA000003861 (arrow indicates a membranous fold near the tip of the ventro-apical spine) 89 P. confusa DEI-GISHym31265 90 P. confusa PR.460VV 91 P. subopaca DEI-GISHym80030, left penis valve 92 P. subopaca paratype http://id.luomus.fi/GL.5203 93 P. pusilla DEI-GISHym80029, left penis valve with strong dorsal depression of the pseudoceps (arrow) 94 P. pusilla DEI-GISHym80029, right penis valve with weak dorsal depression of the pseudoceps 95 P. opaca PR.459VV 96 P. opaca http://id.luomus.fi/GL.5206, paratype of P. amaura Lindqvist.

Figures 97–104.

Penis valves of Pristiphora ruficornis group and P. rufipes. 97 P. staudingeri PR.361VV 98 P. staudingeri PR.447VV 99 P. staudingeri PR.352VV 100 P. staudingeri PR.453VV 101 P. beaumonti DEI-GISHym21176 102 P. staudingeri DEI-GISHym21228 103 P. luteipes DEI-GISHym19681 104 P. rufipes DEI-GISHym15263.

Phylogeny of the Pristiphora ruficornis group and characterisation of subgroups

Genetic data reveal five well separated subgroups within the ruficornis group, which correlate well with morphological and ecological data. According to phylogenetic analyses of COI sequences (Fig. 1), Pristiphora appendiculata together with P. ribisi (identified based on the description and the pictures of the saw given by Togashi 1990) form a sister group (appendiculata subgroup) to a clade containing all other species (we were unable to amplify TPI for any specimens of P. appendiculata and P. ribisi, possibly because of low DNA quality). This is supported by morphological data: species of the appendiculata subgroup are the only species in the ruficornis group having simple claws (Fig. 30) and a completely smooth mesopostnotum (Fig. 7). The host plants of P. appendiculata and P. ribisi (Ribes spp.) also differ from those of other species. The second group (ruficornis subgroup) includes two species (P. ruficornis and P. melanocarpa) feeding on Betula, females of which have a lobe at the base of tangium of the lancet that is often visible without dissection (Fig. 14) and males of which have a membranous fold near or covering the tip of the ventro-apical spine (Figs 79–82). The host plants and genetics are not known for P. frigida, but because of the similar membranous fold of penis valves (Fig. 88), this species might be related to P. ruficornis and P. melanocarpa. The third group (albitibia subgroup) includes three species feeding on Fabaceae (P. astragali, P. albitibia, and P. sootryeni), which have, uniquely within the ruficornis-group, on the inner surface of the lancet small spiny pectines (or dentes semicirculares) that reach the sclerora (Figs 41–45). The fourth group (armata subgroup) includes two species that feed on Crataegus (P. armata) and Tilia (P. leucopus), males of which have uniquely within Pristiphora, but similarly to Euura (as defined by Prous et al. 2014), a distinct apical projection at the posterior end of tergum 8 (Fig. 16). The last, fifth group (aphantoneura subgroup), includes mainly species feeding on Salix, but P. aphantoneura feeds on Fabaceae (Lathyrus pratensis L.) and host plants are not known for P. opaca and P. pusilla. There appear to be no morphological characters that uniquely define the aphantoneura subgroup.

Assessment of morphological characters of the adults

Because of the high similarity of the species in ruficornis group, the number of external characters that can be used for species identification is rather small. These include colour of trochanters, trochantelli, metafemur (Figs 21–23), flagellum (Figs 24–26, 35–36), and pterostigma (Figs 27–29); sculpture of mesopostnotum (Figs 7–8) and mesepisternum (Figs 18–29); size of the subapical tooth (Figs 30–34); and shape of tergum 8 in males (Figs 16, 18). Shape of frontal area as used by Lindqvist (1955) and followed by Benson (1958) was found not to be a reliable character for species identification. Most of these characters vary continuously within the group and sometimes there is a large degree of variation also within species. Nevertheless, these characters can be useful to recognise species, because usually there are different tendencies in different species. The shape of tergum 8 in males of P. armata and P. leucopus (with distinct apical projection; Fig. 16) is the clearest character to distinguish the males of these species from all other Pristiphora (Fig. 17). Sculpture of mesopostnotum and the presence or absence of a subapical tooth on the claws are also good characters to recognise P. appendiculata (smooth mesopostnotum and simple claws; Figs 7, 30) from other European species (matt mesopostnotum and claws with at least a small subapical tooth; Figs 8, 31–34) in the group. Size or the shape of the subapical tooth is also a relatively stable character. Two species (P. bifida, P. frigida) have a long subapical tooth close to the apical one (bifid; Fig. 34), while others have a large or small subapical tooth clearly separated from apical one (Figs 31–33), although this difference can be rather small when compared to large subapical tooth of P. armata and P. leucopus. Antennae vary from completely black to completely yellow, depending on the species, being either always black (Figs 24, 35), black or ventrally pale (Fig. 25, 36), or always at least ventrally pale (Figs 25–26, 36). Trochanters, trochantelli, and pterostigma show a similar pattern of variation. The metafemur is completely black in most species, but in a few species it is often or always partly or completely pale (Figs 21–23). If the metafemur is pale, it can be either whitish (as in P. appendiculata and P. leucopus; Fig. 22) or yellowish (P. aphantoneura and P. luteipes; Fig. 23), although this distinction is not particularly clear. Sculpture of mesepisternum varies from completely smooth to strongly matt, depending on the species, being either always smooth (Fig. 18), smooth or slightly matt (Fig. 19), or usually strongly matt (Fig. 20).

Characters of the lancet that can be used for species identification are the shape of the tangium and serrulae, number of ctenidia, and the presence or absence of small spiny pectines. The tangium can have a distinct lobe (Figs 14, 4653) or a membranous fold (Fig. 64–65). Depending on the species, there are (almost) no (Figs 37–38, 43–44, 4653), few (43–44, 46–53, 72), or many (Figs 39, 41–42, 45, 5471, 73–76) ctenidia. Although the presence of small spiny pectines that reach the sclerora clearly distinguish three species (P. albitibia, P. astragali, and P. sootryeni) from others (Figs 41–45), observing this character is not possible without making slide preparations and examining them under a microscope. The shape of the serrulae has rather limited utility for distinguishing species in the ruficornis group. Only P. appendiculata has distinctly different apical and middle serrulae from other species. Serrulae of this species have an almost non-serrate (without denticles) ventro-apical surface (Figs 37–38), while in others it is clearly serrate (with numerous denticles) (Figs 39, 4176). Structure of serrulae in the remaining species is rather similar, but shape can be sufficiently distinct to distinguish between at least some species (e.g. between P. confusa and P. opaca; Figs 62–65).

The clearest differences between species in the ruficornis group are found in the penis valves. Shape of the ventro-apical spine and pseudoceps usually show distinct and stable differences between most species. In P. frigida (Fig. 88), P. melanocarpa (Figs 80, 82), and P. ruficornis (Figs 79, 81) there is also a membranous fold near to or covering the tip of the ventro-apical spine that is missing in other species. Interestingly, we discovered that left and right penis valves differ consistently and distinctly in shape in P. pusilla. The left penis valve (Fig. 93) has a noticeably stronger dorsal depression in the middle of the pseudoceps and a more strongly bent ventro-apical spine than the right one (Fig. 94). Among sawflies, asymmetrical penis valves have been observed also for Cladius compressicornis (Fabricius, 1804) (Benson 1958; as Priophorus pallipes). Asymmetrical genitalia are apparently very rare in Hymenoptera, as Huber et al. (2007) did not mention any cases for this group in their review.

Dichotomous key to Pristiphora ruficornis group adults

1 a Mesopostnotum smooth (Fig. 7)
b Claws without subapical tooth (Fig. 30)
c Mesepisternum smooth (Fig. 18)
d Antenna usually ventrally paler than dorsally (Fig. 25) P. appendiculata
aa Mesopostnotum matt (Fig. 8)
bb Claws with subapical tooth (Figs 31–34)
cc Mesepisternum smooth or matt (Figs 18–20)
dd Antenna uniformly black or ventrally paler than dorsally (Figs 24–26, 36) 2
2(1) a Metafemur pale in most part (Figs 22–23) 3
aa Metafemur black in most part (Fig. 21) 4
3(2) a Claws with large subapical tooth (Fig. 33)
b Antenna ventrally paler than dorsally (Figs 25, 36) or uniformly yellow (Fig. 26)
c Metafemur whitish (Fig. 22) P. leucopus in part
aa Claws with small subapical tooth (Fig. 31)
bb Antenna uniformly black (Fig. 24)
cc Metafemur yellowish (Fig. 23) females of P. aphantoneura (on Lathyrus) and P. luteipes (on Salix) (see Vikberg 2006 for minor characters for separating these species)
4(2) a Claws with long subapical tooth close to apical one (bifid) (Fig. 34) 5
aa Claws with small or large subapical tooth clearly separated from apical one (Figs 31–33) 6
5(4) a Hind trochanters, trochantelli, and tibia partly pale
b Antenna (usually?) ventrally at least slightly paler than dorsally (Figs 25, 36)
c In males, antennae with numerous and clearly visible stout black setae among finer paler ones (Fig. 36)
d Apical serrulae of lancet short and protruding, and tangium long and narrow (Fig. 70)
e Penis valve without membranous fold near tip of ventro-apical spine and pseudoceps with distinct dorsal depression in middle or basal part (Fig. 87) P. bifida
aa Hind trochanters, trochantelli, and tibia uniformly black or brown
bb Antenna uniformly black (Fig. 24)
cc In males, antennae with only some barely visible stout black setae among finer paler ones (Fig. 35)
dd Apical serrulae of lancet long and flat, and tangium short and broad (Fig. 71)
ee Penis valve with membranous fold near tip of ventro-apical spine and pseudoceps without dorsal depression in middle or basal part (Fig. 88) P. frigida
6(4) a ♀ 7
aa ♂ 17
7(6) a Tangium of lancet with distinct lobe (Figs 14, 4653)
b Mesepisternum smooth (Fig. 18)
c Claws with small subapical tooth (rarely with large) (Fig. 31) 8
aa Tangium of lancet without distinct lobe (Figs 41–45, 54–57, 6269, 7276)
bb Mesepisternum smooth or matt (Figs 18–20)
cc Claws with small or large subapical tooth (Figs 31–33) 9
8(7) a Antenna ventrally distinctly paler than dorsally (Fig. 25) P. ruficornis
aa Antenna usually uniformly black (Fig. 24), but sometimes ventrally slightly paler than dorsally P. melanocarpa
9(7) a Inner surface of lancet with small spiny pectines (or dentes semicirculares) that reach sclerora (Figs 41–45) (visible only by examining slide preparations of the lancet with high magnification) 10
aa Inner surface of lancet without small spiny pectines (Figs 54–57, 6269, 7276) 12
10(9) a Mesepisternum smooth (Fig. 18)
b Lancet with numerous ctenidia (Figs 41–42)
c Apical serrulae of lancet short (Figs 41–42)
d Pterostigma basally dark brown and apically brown (Fig. 28) P. albitibia
aa Mesepisternum at least slightly matt (Figs 19–20)
bb Lancet with numerous or few ctenidia (Figs 43–45)
cc Apical serrulae of lancet short or long (Figs 43–45)
dd Pterostigma uniformly yellow or brown (Fig. 27) 11
11(10) a Lancet with numerous ctenidia (Fig. 45)
b Apical serrulae of lancet long (Fig. 45) P. sootryeni
aa Lancet with few ctenidia (Figs 43–44)
bb Apical serrulae of lancet short (Figs 43–44) P. astragali
12(9) a Lancet with few ctenidia (Fig. 72)
b Serrulae of lancet flat (Fig. 72)
c Antenna (usually?) ventrally slightly paler than dorsally (Fig. 25) P. pusilla
aa Lancet with numerous ctenidia (Figs 54–57, 6269, 73–76)
bb Serrulae of lancet flat or protruding (Figs 54–57, 6269, 73–76)
cc Antenna uniformly black or ventrally paler than dorsally (Figs 24–25) 13
13(12) a Mesepisternum (usually?) strongly matt (Fig. 20)
b Antenna uniformly black (Fig. 24)
c Pterostigma (usually?) uniformly yellow or brown (Fig. 27)
d Arctic habitats P. staudingeri
aa Mesepisternum (usually?) smooth or slightly matt (Figs 18–19)
bb Antenna uniformly black or ventrally paler than dorsally (Figs 24–25)
cc Pterostigma uniformly yellow to dark brown, or basally dark brown and apically brown (Figs 27–29)
dd Usually non-arctic habitats 14
14(13) a Apical serrulae protruding (Figs 54–57, 62–63)
b Antenna often ventrally paler than dorsally (Fig. 25) 15
aa Apical serrulae flat (Figs 6469)
bb Antenna uniformly black or ventrally paler than dorsally (Figs 24–25) 16
15(14) a Pterostigma usually basally dark brown and apically brown (Fig. 28)
b Ctenidia of lancet more distinct (Figs 62–63) P. confusa
aa Pterostigma usually uniformly dark brown (Fig. 29)
bb Ctenidia of lancet less distinct (Figs 54–57) P. armata (on Crataegus) and P. leucopus (on Tilia) in part (see the main text and Grearson and Liston 2012 for discussion separating these species)
16(14) a Tangium of lancet without fold (Figs 66–69)
b Antenna uniformly black (Fig. 24)
c Pterostigma uniformly yellow (Fig. 27) P. subopaca
aa Tangium of lancet with fold (Figs 64–65)
bb Antenna ventrally slightly paler than dorsally (Fig. 25)
cc Pterostigma (usually?) basally dark brown and apically brown (Fig. 28) P. opaca
17(6) a Tergum 8 with apical projection (Fig. 16)
b Antennae ventrally distinctly paler than dorsally or uniformly yellow (Figs 26, 36)
c Claws with large subapical tooth (Fig. 33)
d Mesepisternum smooth (Fig. 18) P. armata (on Crataegus) and P. leucopus (on Tilia) (see the main text and Grearson and Liston 2012 for discussion separating these species)
aa Tergum 8 without apical projection (Fig. 17)
bb Antennae uniformly black to uniformly yellow (Figs 24–26, 36)
cc Claws with small or large subapical tooth (Figs 31–33)
dd Mesepisternum smooth or matt (Figs 18–20) 18
18(17) a Penis valve with membranous fold near or covering tip of ventro-apical spine (Figs 79–82)
b Claws with small subapical tooth (Fig. 31)
c Mesepisternum smooth (Fig. 18) 19
aa Penis valve without membranous fold (Figs 78, 89103)
bb Claws with small or large subapical tooth (Figs 31–33)
cc Mesepisternum smooth or matt (Figs 18–20) 20
19(18) a Ventro-apical spine of penis valve less sharply bent (forming half circle) (Figs 79, 81) P. ruficornis
aa Ventro-apical spine of penis valve more sharply bent (being almost L-shaped) (Figs 80, 82) P. melanocarpa
20(18) a Pseudoceps of penis valve short and broad (Fig. 78)
b Mesepisternum smooth (Fig. 18)
c Antennae uniformly black (Fig. 24)
d Pterostigma (usually?) basally dark brown and apically brown (Fig. 28) P. albitibia
aa Pseudoceps of penis valve longer and narrower (Figs 89103)
bb Mesepisternum smooth or matt (Figs 18–20)
cc Antennae uniformly black (Fig. 24) or ventrally paler than dorsally (Fig. 36)
dd Pterostigma uniformly yellow to uniformly dark brown (Figs 27–29) 21
21(20) a Penis valve with weakly bent and broad ventro-apical spine, and with narrow pseudoceps without distinct dorsal depression in middle part (Figs 89–90) P. confusa
aa Penis valve with different combination of characters (Figs 91103) 22
22(21) a Ventro-apical spine of penis valve narrow and with blunt tip (Figs 95–96)
b Antennae ventrally paler than dorsally (Fig. 36) P. opaca
aa Ventro-apical spine of penis valve broad or narrow and with sharp tip (Figs 91–94, 97–103)
bb Antennae uniformly black (Fig. 24) or ventrally paler than dorsally (Fig. 36) 23
23(22) a Ventro-apical spine of penis valve narrow (Figs 97–103)
b Antennae uniformly black (Fig. 24) 24
aa Ventro-apical spine of penis valve broad (Figs 91–94)
bb Antennae uniformly black (Fig. 24) or ventrally paler than dorsally (Fig. 36) 25
24(23) a Mesepisternum smooth to slightly matt (Figs 18–19)
b Usually non-arctic habitats P. luteipes
aa Mesepisternum usually strongly matt (Fig. 20)
bb Arctic habitats P. staudingeri
25(23) a Pseudoceps of left and right penis valve without distinct dorsal depression in middle part and with weakly bent ventro-apical spine (Figs 91–92)
b Antennae uniformly black (Fig. 24) P. subopaca
aa Pseudoceps of left penis valve with distinct dorsal depression in middle part and with strongly bent ventro-apical spine (Fig. 93)
bb Antenna ventrally paler than dorsally (Fig. 36) P. pusilla

Taxonomy

Pristiphora albitibia (Costa, 1859)

Nematus albitibia Costa, 1859: 21. Syntype(s) ♂ possibly in MZUN, not examined. Type locality: Sila Grande, Calabria, Italy.

Nematus puncticeps Thomson, 1863: 619. Syntypes ♀♂ in MZLU, examined. Type locality: Dalarne, Stockholm, Ostergöthland, Småland, and Skåne, Sweden.

Nematus agilis Zaddach in Brischke, 1884: 142. Primary homonym of Nematus agilis Cresson, 1880 [= Euura agilis (Cresson, 1880)]. 3 ♂♀ syntypes possibly destroyed (Blank and Taeger 1998). Type locality: not specified, but probably in former East Prussia (now Kaliningrad Oblast of Russia, or Poland).

Pristiphora aterrima Lindqvist, 1977: 92, syn. n. Holotype ♀ (DEI-GISHym20896) in MZH, examined. Type locality: Tolyany, Usolje, Irkutsk, Russia.

Similar species

Externally, the most similar species are P. armata, P. confusa, P. leucopus, P. opaca, and P. subopaca, from which it is best distinguished by the structure of the saw (Figs 41–42) and the penis valve (Fig. 78). On the inner surface of the lancet there are small spiny pectines (or dentes semicirculares) that reach the sclerora, which are absent in other similar species. The saw (Fig. 42) and external morphology of the holotype of Pristiphora aterrima Lindqvist, 1977 is not distinguishable from the studied P. albitibia specimens and therefore we synonymise aterrima with albitibia.

Genetic data

Based on COI barcode sequences, P. albitibia belongs to its own BIN cluster (BOLD:ACH1762) (Fig. 1). The nearest neighbour (BOLD:AAL8277, P. astragali?) is 2.06% different. Although there are no nuclear TPI sequences for any of the genetically closest (according to COI barcodes) species (P. astragali and P. sootryeni), the three sequenced specimens of P. albitibia are nearly identical to each other (one specimen differed by one nucleotide from the other two) and clearly different from the other sequenced species (Fig. 2).

Host plants

Vicia cracca L. (Stein 1885, as P. puncticeps; Vikberg 2006), V. hirsuta (L.) Gray, V. tetrasperma (L.) Schreb. (Kangas 1985, as P. puncticeps),Vicia baicalensis Turcz., Vicia unijuga A. Br. (Verzhutskii 1981, as P. puncticeps).

Distribution and material examined

Palaearctic. Specimens studied are from Estonia, Finland, Germany, Russia, and Sweden.

Pristiphora aphantoneura (Förster, 1854)

Tenthredo fulvipes Fallén, 1808: 113. Primary homonym of Tenthredo fulvipes Scopoli, 1763 [= Aglaostigma (Astochus) fulvipes (Scopoli, 1763)]. Lectotype ♀ (designated by Vikberg 2006) in MZLU, examined. Type locality: Sweden.

Nematus aphantoneurus Förster, 1854: 323–325. Lectotype ♀ (DEI-GISHym31561; designated by Vikberg 2006) in ZSM, examined. Type locality: Aachen, North Rhine-Westphalia, Germany.

Cryptocampus distinctus Costa, 1882: 198. Syntype(s) ♀ possibly in MZUN, not examined. Type locality: Oschiri, Sardinia, Italy. Note. Identity of the type(s) is uncertain, could be P. luteipes.

Pristiphora pygmaea Lindqvist, 1964: 130. Holotype ♀ in MZH, examined. Type locality: Helsinki, Finland.

Similar species

The most similar species is P. luteipes, from which it cannot be always distinguished morphologically. Vikberg (2006) mentions that the mesepisternum is completely smooth unlike in P. luteipes, which should show at least slightly coriaceous sculpture (Fig. 19 and Fig. 6a in Vikberg 2006). However, P. luteipes can also have a completely smooth mesepisternum, especially in southern European specimens. See Vikberg (2006) for additional minor characters for separating these species. Males are unknown.

Genetic data

Based on a COI barcode sequence of one confidently identified specimen (reared ex ovo from Lathyrus pratensis) from Finland (DEI-GISHym80037), it belongs to the same BIN cluster (BOLD:AAG3568) as P. bifida, P. confusa, P. luteipes, P. opaca, P. pusilla, P. staudingeri, and P. subopaca (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. Amplification of TPI of the specimen DEI-GISHym80037 failed, but we were able to obtain this nuclear sequence for one specimen from Estonia (DEI-GISHym31258) which had a nearly identical COI barcode (one nucleotide difference). Because the mesepisternum of this female was completely smooth, we identified it as P. aphantoneura. If this is correct, then TPI sequence data would be consistent in separating P. aphantoneura from closely related P. luteipes feeding on Salix (Fig. 2), although more specimens and some other nuclear sequences should be sampled to confirm this.

Host plants

Lathyrus pratensis L. (Vikberg 2006).

Distribution and material examined

Palaearctic. Specimens studied are from Estonia, Finland, and Germany.

Pristiphora appendiculata (Hartig, 1837)

Pristiphora pallipes Serville, 1823: 75. Secondary homonym of Tenthredo pallipes Fallén, 1808 [= Pristiphora (Lygaeotus) carinata (Hartig, 1837)]. Lectotype ♀ (designated by Lacourt 2000) in MNHN, not examined. Type locality: Paris, France.

Pristiphora pallipes Lepeletier, 1823: 60. Primary homonym of Pristiphora pallipes Serville, 1823 [= Pristiphora (Pristiphora) appendiculata (Hartig, 1837)]. Lectotype ♀ (designated by Lacourt 2000) in MNHN, not examined. Type locality: Paris, France.

Tenthredo (Nematus) pallicornis T.W. Harris, 1835: 583. Type(s) not available. Nomen nudum.

Tenthredo (Nematus) labrata T.W. Harris, 1835: 583. Type(s) not available. Nomen nudum.

Nematus flavipes Dahlbom, 1835a: 25–26. Nomen oblitum. Holotype ♀ in MZLU, examined. Type locality: Lund, Sweden.

Nematus appendiculatus Hartig, 1837: 202–203. Nomen protectum. See Blank et al. (2009). Lectotype ♀ (GBIF-GISHym3197; here designated) in ZSM, examined. Type locality: Germany according to the title of the publication.

Nematus fuscicornis Hartig, 1837: 225. No syntypes were found in ZSM. Type locality: Harz, Germany.

Nematus enervis Herrich-Schäffer, 1840: 176. Replacement name for Pristiphora pallipes Lepeletier, 1823.

Nematus cathoraticus Förster, 1854: 325–326. Lectotype ♀ (GBIF-GISHym3214; here designated) in ZSM, examined. Type locality: Aachen, North Rhine-Westphalia, Germany.

Nematus pallicornis Norton, 1861: 160. 3 ♀ syntypes in MCZ (http://140.247.119.225/mcz/Species_record.php?id=22468), although 4 specimens were mentioned in the original description, not examined. Type locality: Massachusetts, USA.

Nematus pallicornis var. labratus Norton, 1861: 160. Holotype ♀ possibly in ANSP or MHNG, not examined. Type locality: Massachusetts, USA. Note. Nematus labratus Norton, 1861 and Nematus pallicornis var. labratus Norton, 1862 (Norton 1861) were wrongly both listed as available names by Taeger et al. (2010). They refer to the same nominal taxon, described together with N. pallicornis in a single text section by Norton (1861). In the headline to this section, Norton mentions the manuscript names N. pallicornis and N. labratus (nomina nuda) used by Harris (1835). At the end of his description, Norton wrote “A variety named labratus, by Dr. Harris [...]”. The name labratus was therefore originally published as a variety.

Pristiphora grossulariae Walsh, 1866: 123. Neotype ♀ (selected by Zinovjev and Smith 2000) in ANSP, not examined. Type locality: possibly (if the neotype belongs to syntype series) Davenport, Iowa, USA.

Nematus Peletieri [sic!] André, 1880: 111. Name for Pristiphora pallipes Lepeletier, 1823.

Nematus hypobalius Zaddach in Brischke, 1884: 154. Holotype ♀ possibly destroyed (Blank and Taeger 1998). Type locality: Hungary.

Nematus pumilus Zaddach in Brischke, 1884: 172. 2 ♂ syntypes possibly destroyed (Blank and Taeger 1998). Type locality: Chernyakhovsk [Insterburg], Kaliningrad Oblast, Russia.

Nematus Ghilianii [sic!] Costa, 1894: 73. Syntype(s) ♂ possibly in MZUN, not examined. Type locality: Alps [Alpi boreali], Europe.

Similar species

Smooth mesopostnotum (Fig. 7) and claws without subapical tooth (Fig. 30) allow unambiguous distinction of this species from other European species of the ruficornis group. A specimen from China (DEI-GISHym17879) that can be identified as P. ribisi Togashi, 1990 (described from Japan), is externally not distinguishable from P. appendiculata, but has a distinctly different saw (Fig. 39) by having well developed ctenidia and serrulae with numerous denticles on the ventro-apical surface (ctenidia are practically absent and serrulae are almost without denticles on the ventro-apical surface in P. appendiculata; Figs 37–38).

Genetic data

Based on COI barcode sequences, specimens of this species are divided between two BIN clusters (BOLD:AAG7866 and BOLD:AAU8684). Minimum distance between the clusters is 3.26%. However, one of the BINs might represent a cluster of nuclear mitochondrial pseudogenes (NUMTs). The COI sequence (1078 bp) we obtained from the specimen DEI-GISHym21073 was different (belonging to BOLD:AAG7866) from the one present in BOLD (BASYM3303-14, 652 bp; belonging to BOLD:AAU8684) (Fig. 1). Our use of different primers (see Material and methods) from those used by the Canadian Centre for DNA Barcoding might explain the result. Because the sequences under BOLD:AAU8684 (all 8 sequences in BOLD are identical) have an unusual 6-nucleotide deletion and this BIN forms a distinctly longer branch (which means more mutations) in the phylogenetic tree (Fig. 1) than other sequences in the appendiculata subgroup, it might represent the NUMT cluster rather than BOLD:AAG7866. Alternatively, specimen DEI-GISHym21073 might be heteroplasmic for mitochondrial DNA (different mitochondria co-existing in the same cell or individual). Because sequences from both of these BINs can apparently be present in the same individual, these BINs seem to form a monophyletic group (Fig. 1), and because there appear to be no morphological characters that distinguish these BIN clusters, we treat them as one species. Closest to these BIN clusters is a specimen from China that we identified as P. ribisi (Fig. 1). Amplification of nuclear TPI sequences was unfortunately unsuccessful.

Host plants

Ribes spp. Ribes alpinum L. (Kangas 1985, as P. rufipes), R. rubrum L. (Adam 1973, as P. pallipes), R. uva-crispa L. emend. Lam. (Adam 1973; Kangas 1985), R. aureum Pursh (Adam 1973), R. sanguineum Pursh (Adam 1973), R. nigrum L. (Adam 1973), R. spicatum Robs. (Kontuniemi 1975, as P. pallipes).

Distribution and material examined

Palaearctic, Nearctic. Specimens studied are from Austria, Canada, Estonia, Finland, Germany, Russia, and Sweden.

Pristiphora armata (Thomson, 1863)

Nematus crassicornis Hartig, 1837: 204–205. Primary homonym of Nematus crassicornis Stephens, 1829 [= Cladius (Cladius) pectinicornis (Geoffroy, 1785)]. 3 ♀♀ and 13 ♂♂ possible syntypes belonging to P. armata and P. leucopus in ZSM, examined. Type locality: Germany according to the title of the publication.

Nematus armatus Thomson, 1863: 619. Seven possible female syntypes belonging to P. armata and P. leucopus in MZLU, examined. Type locality: Bohus Län (Bohuslän), Stockholm, and Skåne, Sweden.

Nematus crataegi Brischke, 1883: pl. I(7), 6. Syntype(s) possibly destroyed (Blank and Taeger 1998). Type locality: not stated, but probably in former East Prussia (now Kaliningrad Oblast of Russia, or Poland).

Nematus Fletcheri [sic!] Cameron, 1884: 26. Syntype(s) possibly in BMNH, not examined. Type locality: Worcester and Clydesdale, United Kingdom.

Nematus melanostomus Zaddach in Brischke, 1884: 140–141. Holotype ♀ possibly destroyed (Blank and Taeger 1998). Type locality: Bautzen, Saxony, Germany.

Nematus ensicornis Jacobs, 1884: XXIII. Syntype(s) ♀ possibly in IRSNB, not examined. Type locality: near Brussels, Belgium.

Nematus nigricollis Cameron, 1885: 66. Syntype(s) possibly in BMNH, not examined. Type locality: Worcester, United Kingdom.

Similar species

The most similar species is P. leucopus. Differences between these two species were extensively discussed by Grearson and Liston (2012). Briefly, specimens, both male and female, with completely or nearly completely pale metafemur (Fig. 22) belong to P. leucopus, but specimens with black or mostly black metafemur (Fig. 21) cannot be distinguished externally. Unfortunately, differences in lancets (Figs 54–57) and penis valves (Figs 83–86) are also small and might not always be detectable. According to Grearson and Liston (2012), the general proportions of the lamnium of P. armata (Figs 56–57) are wider than that of P. leucopus (Fig. 54), but this does not always work, because P. leucopus can have a distinctly wider lamnium than P. armata, though serrulae are in this case somewhat weaker (Fig. 55). Males can perhaps be distinguished through small differences in penis valves (Figs 85–86 and Figs 9–10 in Grearson and Liston 2012), as described by Grearson and Liston (2012): “In P. armata, the outer edge of the spine has a short straight section near the apex, terminated ventrally by a marked angle and below this a second section which is almost straight; there is a noticeable narrowing of the width of the spine at this point. In P. leucopus, the spine is almost parallel with a smoothly-curved outer edge and only a slight narrowing near the base”. Unfortunately, the differences are not always evident (Figs 83–84). Females might be confused also with some specimens of P. confusa (if they have completely smooth mesepisternum), the only differences perhaps being the colour of pterostigma (uniformly dark brown in P. armata, usually basally dark brown and apically brown in P. confusa) and small differences in the lancet (ctenidia tend be more distinct in P. confusa; Figs 62–63). Differences in host plant use are the only reliable way to separate P. armata from P. leucopus that have a black metafemur (Crataegus in P. armata, Tilia in P. leucopus). Because of difficulties separating these species, we refrain from selecting lectotypes (in agreement with Grearson and Liston 2012) for crassicornis Hartig and armatus Thomson at this stage.

Genetic data

Based on COI barcode sequences, P. armata belongs to the same BIN cluster (BOLD:AAQ2302) as P. leucopus (Fig. 1). The nearest neighbour (BOLD:AAG3568) is 2.76% different. BOLD:AAG3568 includes P. aphantoneura, P. bifida, P. confusa, P. luteipes, P. opaca, P. pusilla, P. staudingeri, and P. subopaca. Although we have only one TPI sequence of P. armata, it also does not allow separation of P. armata from P. leucopus (Fig. 2). The single P. armata sequence would be identical to the single available P. leucopus female sequence when ambiguous positions due to heterozygosity are excluded. Examination of all the six heterozygous sites (double peaks in chromatograms) in P. leucopus revealed that all of them include also the nucleotide found in P. armata, possibly indicating haplotype sharing between these two taxa.

Host plants

Crataegus species (Brischke 1883; Grearson and Liston 2012).

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland, France, Germany, Italy, and Sweden.

Pristiphora astragali Vikberg, 1978

Pristiphora astragali Vikberg, 1978: 133–137. Holotype ♀ (PR.354VV) in MZH, examined. Type locality: Kilpisjärvi, Finland.

Similar species

Based on the external morphology, the most similar species are P. confusa, P. opaca, P. pusilla, P. sootryeni, P. staudingeri, and P. subopaca, from which it is best distinguished by the structure of the lancet (Figs 43–44). The lancet has weak ctenidia (weak or well-developed in the others) and on the inner surface of the lancet there are small spiny pectines (or dentes semicirculares) that reach the sclerora (present also in P. sootryeni). However, differences from P. sootryeni (Fig. 45) are rather small. Morphologically, the subapical tooth of the claws tends be smaller, the apical serrulae of the lancet are shorter, and the number of ctenidia on the lancet is smaller than in P. sootryeni (Vikberg 2006). Male unknown.

Genetic data

Based on a COI barcode sequence of one confidently identified specimen of P. astragali from Abisko (Sweden; DEI-GISHym80042), it belongs to the same BIN cluster as P. sootryeni (BOLD:AAL8292), which in the BOLD database includes two other unidentified specimens from Manitoba, Canada (Fig. 1). The nearest neighbour (BOLD:AAL8277) is 2.40% different. BIN cluster BOLD:AAL8277 includes possibly also P. astragali: in the BOLD database there are two specimens from Manitoba (Canada) and one from Inari (Finland), the latter identified by Matti Viitasaari as “Pristiphora nr. astragali”. Amplification of TPI failed.

Host plants

Astragalus alpinus L. (Vikberg 1978; 2006).

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland and Sweden.

Pristiphora bifida (Hellén, 1948)

Nematus (Pristiphora) bifidus Hellén, 1948: 116–117. Lectotype ♀ (http://id.luomus.fi/GL.5214; here designated) in MZH, examined. Type locality: Malla, Kilpisjärvi, Enontekiö, Finland.

Similar species

Externally, perhaps the most similar species is P. frigida, from which it can be distinguished by having pale hind trochanters, trochantelli, and tibiae (black or brown in P. frigida). In addition, antennae of males have numerous and clearly visible stout black setae among finer paler ones (Fig. 36), while in P. frigida there are only a few barely visible ones (Fig. 35). The lancets (Figs 70–71) and penis valves (87–88) are also different. Apical serrulae are somewhat shorter and more protruding and the tangium of the lancet tends to be longer and narrower (Fig. 70) than in P. frigida (Fig. 71). The penis valve lacks (Fig. 87) a membranous fold near the tip of the ventro-apical spine (present in P. frigida; Fig. 88) and the pseudoceps has a distinct dorsal depression in the middle or basal part (absent in P. frigida).

Genetic data

Based on COI barcode sequences, P. bifida belongs to the same BIN cluster (BOLD:AAG3568) as P. aphantoneura, P. confusa, P. luteipes, P. opaca, P. pusilla, P. staudingeri, and P. subopaca (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. Only one partial TPI sequence (sequencing of the first exon and part of the following intron failed apparently because of intron length polymorphism) of P. bifida is available, which can be distinguished from other species (Fig. 2).

Host plants

Salix viminalis L. (Liston and Burger 2009). In Kilpisjärvi (Finland) some other species must be the host, as S. viminalis does not occur there.

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland, Germany, Norway, and Sweden. According to the BOLD database, this species may also be present in North America. The identifications of North American specimens falling within BIN cluster BOLD:AAG3568 are however uncertain.

Pristiphora confusa Lindqvist, 1955

Pristiphora confusa Lindqvist, 1955: 40–41. Holotype ♀ (http://id.luomus.fi/GL.5209) in MZH, examined. Type locality: Sipoo [Sibbo], Uusimaa, Finland.

Similar species

Based on the external morphology, the most similar species are P. albitibia, P. armata, P. leucopus, P. opaca, P. pusilla, P. sootryeni, and P. subopaca. The species is best distinguished through the structure of male penis valve (Figs 89–90). Unfortunately, it is rather difficult to distinguish females from P. armata, P. leucopus, P. opaca, and P. subopaca, as the differences in lancets are small (Figs 54–57, 6269). Apical serrulae are more protruding and shorter than in P. opaca and P. subopaca (Figs 6269). Pristiphora opaca also has a fold at the base of tangium of the lancet (Figs 64–65) that is lacking in other species in the ruficornis group. Pristiphora opaca tends also to have a smaller subapical tooth than P. confusa. The pterostigma of P. confusa is apically brown and basally dark brown, like in P. opaca (Fig. 28), but unlike in P. subopaca, in which it is uniformly yellow (Fig. 27). In P. armata and P. leucopus, the pterostigma is usually dark brown (Fig. 29), but sometimes the pterostigma can have more or less the same colour as in P. confusa. In this case, small differences in the lancet can help distinguish P. confusa from P. armata and P. leucopus, as ctenidia tend to be more distinct in P. confusa (Figs 54–57, 62–63). Among the males, the most similar penis valves are of P. subopaca. The ventro-apical spine in P. confusa is barely bent and the pseudoceps is narrower compared to P. subopaca (Figs 89–92).

Genetic data

Based on COI barcode sequences, P. confusa belongs to the same BIN cluster (BOLD:AAG3568) as P. aphantoneura, P. bifida, P. luteipes, P. opaca, P. pusilla, P. staudingeri, and P. subopaca (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. Two available TPI sequences (one male and one heterozygous female) group weakly together and can be distinguished from other species (Fig. 2).

Host plants

Salix caprea L. (Kangas 1985), Salix fragilis L. (Benson 1958), Salix phylicifolia L. (Benson 1958).

Distribution and material examined

Western Palaearctic. Specimens studied are from Estonia, Finland, France, Germany, Sweden, and Switzerland.

Pristiphora frigida (Boheman, 1865)

Nematus frigidus Boheman, 1865: 568–569. Lectotype ♂ (NHRS-HEVA000005005; here designated) in NHRS, examined. Type locality: “Middel Hook in Belsund” (Spitsbergen Island), Svalbard, Norway.

Pristiphora Adelungi [sic!] Konow, 1902: 162, 167–168. Lectotype ♀ (DEI-GISHym30151; here designated) in ZIN, examined. Type locality: Hornsund (Spitsbergen Island), Svalbard, Norway. Note. Additional male specimen of P. adelungi labelled as “TYPE” is deposited in SDEI. Since this specimen lacks labels with detailed information given in the original description, its type status remains uncertain.

Similar species

Externally, perhaps the most similar species is P. bifida, from which it can be distinguished by having black or brown hind trochanters, trochantelli, and tibiae (pale in P. bifida). In addition, antennae of males have only some barely visible stout black setae among finer paler ones (Fig. 35), while these are numerous and clearly visible in P. bifida (Fig. 36). On the other hand, the penis valve (Fig. 88) might indicate a closer relationship to P. melanocarpa and P. ruficornis (Figs 79–82), because of a membranous fold near the tip of the ventro-apical spine that is missing in other species of ruficornis group. The tangium of the lancet (Fig. 71) also resembles more closely the Betula feeding P. melanocarpa and P. ruficornis (Figs 4653) rather than P. bifida (Fig. 70): the dark sclerotized area is rather broader than long instead of longer than broad.

Genetic data

No data.

Host plants

Unknown.

Distribution and material examined

Western Palaearctic. Specimens studied are from Norway (Svalbard).

Pristiphora leucopus (Hellén, 1948)

Nematus vitreipennis Eversmann in Kawall, 1864: 295, syn. n. Nomen oblitum. Note. Kawall (1864) published an unaltered manuscript from Eversmann’s legacy. Lectotype ♀ (DEI-GISHym30027; here designated) in ZIN, examined. Type locality: foothills of Ural mountains [In promontor. Uralensibus], Russia.

Nematus (Pristiphora) ruficornis var. leucopus Hellén, 1948: 116. Nomen protectum. No syntypes were found in MZH. Type locality: Joutseno, South-Eastern Finland, Finland and Pionerskoye [Kuolemajärvi], Leningrad Oblast, Russia. Note. The lectotype of Nematus vitreipennis (which was the only specimen found under this name in Eversmann’s collection in ZIN) agrees well with the summer morph (completely pale metafemur) of P. leucopus (Grearson and Liston 2012). The name vitreipennis has apparently not been used as valid since 1884 (Brischke 1884), whereas leucopus has been used as the valid name for this taxon more than 25 times by more than 10 different authors since 1955 (Lindqvist 1955). According to Article 23.9.1 (ICZN 1999), the prevailing usage must be maintained.

Similar species

The most similar species to P. leucopus is P. armata. Differences between these two species were extensively discussed by Grearson and Liston (2012). Whereas P. leucopus exhibits seasonal dimorphism of adults, involving leg colour and shape of the serrulae of the lancet, no such dimorphism has been observed in P. armata. Briefly, both male and female specimens which have a completely or nearly completely pale metafemur (Fig. 22) can be distinguished from P. armata (metafemur of which is always completely or in most part black). Other specimens, with a black or mostly black metafemur (Fig. 21), cannot be distinguished externally. Unfortunately, differences in lancets (Figs 54–57) and penis valves (Figs 83–86) are also small and might not always be detectable. According to Grearson and Liston (2012) the general proportions of the lamnium of P. leucopus (Fig. 54) are more slender than that of P. armata (Figs 56–57), but this does not always work, because P. leucopus can have a distinctly wider lamnium than P. armata, though serrulae are in this case somewhat weaker (Fig. 55). Males can perhaps be distinguished through small differences in penis valves (Figs 85–86 and Figs 9–10 in Grearson and Liston 2012), as described by Grearson and Liston (2012) (see also under P. armata). Females with a black metafemur might also be confused with some specimens of P. confusa (if they have a completely smooth mesepisternum). Usually, P. leucopus (Fig. 29) has a uniformly dark brown pterostigma (usually basally dark brown and apically brown in P. confusa; Fig. 28), but the specimens with pterostigma apically paler than basally might not be externally distinguishable from P. confusa. However, small differences in the lancets can help distinguish these species, as ctenidia in P. confusa tend to be more distinct (Figs 62–63).

Genetic data

Based on COI barcode sequences, P. leucopus belongs to the same BIN cluster (BOLD:AAQ2302) as P. armata (Fig. 1). The nearest neighbour (BOLD:AAG3568) is 2.76% different. BOLD:AAG3568 includes P. aphantoneura, P. bifida, P. confusa, P. luteipes, P. opaca, P. pusilla, P. staudingeri, and P. subopaca. Neither does our limited nuclear data allow separation of P. leucopus from P. armata (Fig. 2). The single heterozygous female would have a sequence identical to the single available P. armata sequence if heterozygous sites (double peaks in chromatograms) were excluded. All the six heterozygous sites in P. leucopus include also the nucleotide found in P. armata, possibly indicating haplotype sharing between these two taxa.

Host plants

Tilia cordata Mill. (Kangas 1985; Grearson 2006; Grearson and Liston 2012), Tilia × vulgaris Hayne (Grearson 2006).

Distribution and material examined

Western Palaearctic. Specimens studied are from Austria, Finland, Germany, Great Britain, Russia, and Sweden.

Pristiphora luteipes Lindqvist, 1955

Pristiphora luteipes Lindqvist, 1955: 47–48. Holotype ♀ (DEI-GISHym20897) in MZH, examined. Type locality: Degerby, Uusimaa, Finland.

Similar species

The most similar species is P. aphantoneura, from which it cannot be always distinguished morphologically. Vikberg (2006) mentions that the mesepisternum should show at least slightly coriaceous sculpture (fig. 19 and fig. 6a in Vikberg 2006), but should be completely smooth in P. aphantoneura (Fig. 18). However, the mesepisternum can also be completely smooth in P. luteipes, especially in southern European specimens. See Vikberg (2006) for additional minor characters for separating these species. Pristiphora beaumonti Zirngiebl, 1957 known from North Africa is possibly a synonym of luteipes Lindqvist. All the specimens of P. beaumonti studied from Morocco are extremely pale. Females have a completely yellow abdomen (Fig. 13) and even the thorax often has ventral and dorsal yellow markings. Males are darker: thorax and usually abdomen are black (one studied specimen had an almost completely yellow abdomen). However, all males from Morocco have a completely pale metafemur, unlike males from Portugal and Spain (with a mostly black metafemur), which we have identified as P. luteipes based on females that were collected at the same time from Salix. Females from Portugal, Spain, and Sardinia (Italy) are very similar to North European specimens of P. luteipes, but tend to have a completely smooth mesepisternum and dark brown pterostigma (slightly coriaceous mesepisternum and yellow pterostigma in northern European specimens). However, the degree of coriaceous sculpture on the mesepisternum and the colour of pterostigma vary continuously and seem to correlate with latitude (specimens in the south tend to have a smoother mesepisternum and darker pterostigma). Lancets (Fig. 61) and penis valves (Fig. 101) of P. beaumonti are not distinguishable from P. luteipes (Figs 60, 103) or even from P. staudingeri (arctic or subarctic taxon; Figs 73–76, 97–100, 102). Males of P. luteipes were previously unknown (Vikberg 2006), but appear to be common in southern Europe (at least in Portugal and Spain). We have identified a possible male of P. luteipes (DEI-GISHym80049) also from Sweden, because according to its nuclear TPI sequence it seems to be closer to P. luteipes specimens than to P. staudingeri (Fig. 2), although COI barcode was identical to one of the P. staudingeri specimens (Fig. 1). The male from Sweden has distinctly coriaceous sculpture on the mesepisternum and a paler pterostigma compared to males from Spain and Portugal, which would fit the geographic pattern found in females. Because males of P. luteipes have a black metafemur and the penis valves are indistinguishable from those of P. staudingeri, identification of the Swedish male (Härjedalen at an altitude of 840 m) remains uncertain. Distinguishing females of P. luteipes from P. staudingeri might not always work either, because we have studied two specimens (P. staudingeri?) from Sweden (Jämtland County at an altitude 900 m) that were intermediate in morphology, having partly yellow metafemur (apically slightly yellow in the specimen W10115 and apically half yellow in W10105).

Genetic data

Based on COI barcode sequences, P. luteipes belongs to the same BIN cluster (BOLD:AAG3568) as P. aphantoneura, P. bifida, P. confusa, P. opaca, P. pusilla, P. staudingeri, and P. subopaca (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. It is not clear if nuclear TPI sequences allow better identification of P. luteipes compared to COI barcode sequences, mainly because of the uncertain identity (P. luteipes or P. staudingeri, see above) of the specimen DEI-GISHym80049 (Fig. 2), which seems to be closer to two sequenced P. luteipes specimens than to other species.

Host plants

Salix alba L., S. aurita L., S. babylonica L., S. repens L. S. rosmarinifolia L., S. phylicifolia L., S. viminalis L., S. purpurea L. (see Vikberg 2006); S. cinerea L. and S. fragilis L. (Loiselle 1909, as P. fulvipes).

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland, France, Germany, Great Britain, Italy, Norway, Portugal, Spain, and Sweden.

Pristiphora melanocarpa (Hartig, 1840)

Nematus melanocarpus Hartig, 1840: 27. Lectotype ♀ (GBIF-GISHym3349; here designated) in ZSM, examined. Type locality: North Germany (according to introduction).

Nematus funerulus Costa, 1859: 20–21. Syntypes ♂♀ possibly in MZUN, not examined. Type locality: vicinity of Naples, Campania, Italy.

Nematus wuestneii Stein, 1885 [mandatory correction of incorrect original spelling N. Wüstneii]: 304. Lectotype ♀ (here designated) in BMNH, examined. Type locality: Chodov [Chodau], Czech Republic.

Pristiphora ortinga Kincaid, 1900: 349–350. Holotype ♀ (USNMENT00778199) in USNM, not examined. Type locality: Kukak Bay, Alaska, USA. Note. Synonymised by Smith (1979: 63).

Similar species

The most similar species is P. ruficornis, which has paler antennae compared to P. melanocarpa. Females have the ventral side of antennae uniformly black (Fig. 24) or only slightly paler, while P. ruficornis has a distinctly paler ventral side (Fig. 25). Males of P. melanocarpa also tend to have darker antennae than in P. ruficornis, but penis valves should be studied in specimens that have conspicuously pale antennae. The ventro-apical spine of the penis valve bends distinctly more sharply (being almost L-shaped) and is usually narrower (Figs 80, 82) than in P. ruficornis (Figs 79, 81).

Genetic data

Based on COI barcode sequences, specimens are divided between three BIN clusters (BOLD:AAG3540, BOLD:ACZ4465, BOLD:ACZ4466), two of them (BOLD:ACZ4465 and BOLD:ACZ4466) including also P. ruficornis (Fig. 1). These BIN clusters form a monophyletic group (Fig. 1) and minimum distances between them are only 1.13–1.50%. Neither do nuclear TPI sequences support separation of P. melanocarpa and P. ruficornis (Fig. 2).

Host plants

Betula pendula Roth (Kangas 1985), B. pubescens Ehrh. ssp. czerepanovii (N. I. Orlova) Hämet-Ahti (rearings by VV), B. nana L. (rearings and ex ovo rearing experiments by VV). The records from Salix (e.g. Lorenz and Kraus 1957) are probably based on misidentifications. A male paratype of P. coniceps Lindqvist (http://id.luomus.fi/GL.5208) that belongs to P. melanocarpa, was reared from larvae found on Salix (Lindqvist 1955), but this should not be taken as a clear evidence for host association as no ex ovo rearings were involved.

Distribution and material examined

Holarctic. Specimens studied are from Canada, Estonia, Finland, France, Germany, Norway, and Sweden.

Pristiphora opaca Lindqvist, 1955

Pristiphora opaca Lindqvist, 1955: 42–43. Holotype ♀ (http://id.luomus.fi/GL.5204) in MZH, examined. Type locality: Pihtipudas, Central Finland.

Similar species

Based on the external morphology, the most similar species are P. albitibia, P. confusa, P. pusilla, P. sootryeni, and P. subopaca. The species is best distinguished through the structure of male penis valve (Figs 95–96). Unfortunately, it is rather difficult to distinguish females from P. subopaca as the differences in the lancets are small (Figs 6469). The best character might be the structure of the tangium: on its basal part, P. opaca appears to have a fold (Figs 64–65) that is absent in other species of the ruficornis group, although this observation is based only on two specimens that had saws intact enough to see this (basal part of both lancets was damaged in the third female available for study, the holotype). There are also slight differences in external morphology between P. opaca and P. subopaca. In P. opaca (Fig. 28), the pterostigma is apically brown and basally dark brown (uniformly yellow in P. subopaca; Fig. 27), antennae are slightly paler ventrally (uniformly black in P. subopaca), and claws seem to have a somewhat smaller subapical tooth (Fig. 31) than in P. subopaca (Fig. 32).

Genetic data

Based on COI barcode sequences, P. opaca belongs to the same BIN cluster (BOLD:AAG3568) as P. aphantoneura, P. bifida, P. confusa, P. pusilla, P. staudingeri, and P. subopaca (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. Only one TPI sequence is available, which can be distinguished from other species (Fig. 2).

Host plants

Unknown.

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland and Sweden.

Pristiphora pusilla Malaise, 1921

Pristiphora pusilla Malaise, 1921: 11–12. Lectotype ♂ (NHRS-HEVA000004942; here designated) in NHRS, examined. Type locality: Torne Träsk, Torne Lappmark, Sweden. Note. In the original description, Malaise (1921) mentioned one female and three males collected from Torne Träsk, but only three specimens (a female and two males) probably belonging to the syntype series were found in NHRS. Among these three specimens, only the female carries the labels “Typus” and “Pristiphora pusilla n. sp.” in addition to a locality label “Torne Tr. Malaise”, the two males having originally only the identical locality label “Torne Tr. Malaise” (both males have in addition the label “Pristiphora pusilla Mal. Det: A. Haris 2003” and one of them also apparently relatively recent hand written label “Prist. pusilla”). According to Hege Vårdal (NHRS) there were no other males from Torne Träsk among P. pusilla in the collection and therefore we consider these males as part of the syntype series. Because the female specimen turned out to belong to P. staudingeri (Ruthe, 1859) and in order to preserve the concept of P. pusilla as established by Lindqvist (1953) (who also examined one of the male syntypes), and because separation of males from similar species is more reliable thanks to distinct penis valves, we decided to select one of the males as the lectotype.

Pristiphora amaura Lindqvist, 1955: 43–45. Holotype ♀ (http://id.luomus.fi/GL.5205) in MZH, examined. Type locality: Kangasala, Pirkanmaa, Finland. Note. The male paratype of P. amaura (http://id.luomus.fi/GL.5206) (Fig. 96) was misidentified and belongs to P. opaca Lindqvist, 1955 instead.

Similar species

Based on the external morphology, the most similar species are P. albitibia, P. astragali, P. confusa, P. opaca, P. sootryeni, P. staudingeri, and P. subopaca. The species is best distinguished through the structure of male penis valve (Figs 93–94) and female lancet (Fig. 72). In females, the lack of small spiny pectines (or dentes semicirculares) on the inner surface of the lancet and weakly developed ctenidia, distinguish it from other similar species. Male penis valves are asymmetric (confirmed for six specimens), the left one (Fig. 93) having a noticeably stronger dorsal depression in the middle of pseudoceps and a more strongly bent ventro-apical spine than the right one (Fig. 94). The most similar penis valves are those of P. subopaca (Figs 91–92), which have a less distinct dorsal depression in the middle of pseudoceps and a less strongly bent ventro-apical spine, but this difference is clear only when compared to the left penis valve of P. pusilla. Externally, P. pusilla might be distinguished from P. subopaca by having ventrally paler antennae (uniformly black in P. subopaca; Fig. 24), which is more evident in males (Fig. 36).

Genetic data

Based on COI barcode sequences, P. pusilla belongs to the same BIN cluster (BOLD:AAG3568) as P. aphantoneura, P. bifida, P. confusa, P. opaca, P. staudingeri, and P. subopaca (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. Two available nuclear TPI sequences are identical and distinguishable from other species (Fig. 2).

Host plants

Unknown.

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland, Norway, and Sweden.

Pristiphora ruficornis (Olivier, 1811)

Nematus ruficornis Olivier in Olivier and Manuel 1811: 167. Syntype(s) possibly in MNHN, not examined. Type locality: near Paris, France.

Pristiphora testaceicornis Serville, 1823: 75. Syntype(s) ♂ not found in MNHN (Lacourt 2000). Type locality: Paris, France.

Pristiphora testaceicornis Lepeletier, 1823: 60. Primary homonym of Pristiphora testaceicornis Serville, 1823 [= Pristiphora (Pristiphora) ruficornis (Olivier, 1811)]. Syntype(s) ♂ not found in MNHN (Lacourt 2000). Type locality: Paris, France.

Nematus (Nematus) robustellus Dahlbom, 1835b: 9. Type(s) not available. Nomen nudum.

Nematus fraxini Hartig, 1837: 204. Lectotype ♀ (GBIF-GISHym3285; here designated) in ZSM, examined. Type locality: Harz, Germany.

Nematus testaceicornis Jacobs, 1884: XXIII-XXIV. Syntype(s) ♀ possibly in IRSNB, not examined. Type locality: near Brussels, Belgium.

Nematus (Pristiphora) ruficornis var. integer Hellén, 1948: 116, syn. n. Primary homonym of Nematus integer Say, 1836. Holotype ♀ (http://id.luomus.fi/GL.5212) in MZH, examined. Type locality: Hammaslahti, North Karelia, Finland.

Similar species

The most similar species is P. melanocarpa, which has darker antennae compared to P. ruficornis. Females have a distinctly paler ventral side of antennae (Fig. 25), while antennae in P. melanocarpa are uniformly black (Fig. 24) or have only a slightly paler ventral side. Males of P. ruficornis also have generally paler antennae than in P. melanocarpa (Fig. 26), but penis valves should be studied to distinguish them from P. melanocarpa specimens having conspicuously pale antennae. Ventro-apical spine of penis valve (Figs 79, 81) bends more gradually (forming a half circle) and is usually broader than in P. melanocarpa (Figs 80, 82).

Genetic data

Based on COI barcode sequences, specimens of P. ruficornis are divided between two BIN clusters (BOLD:ACZ4465 and BOLD:ACZ4466) that also include P. melanocarpa (Fig. 1). Minimal distance between these two clusters is only 1.13%. Nuclear TPI sequences do not support separation of P. ruficornis from P. melanocarpa either (Fig. 2). The single sequenced male would be identical to one of the heterozygous P. melanocarpa females when ambiguous positions due heterozygosity are excluded. Examination of all the 14 heterozygous sites (double peaks in chromatograms) in this P. melanocarpa specimen revealed that all of them include also the nucleotide found in P. ruficornis, possibly indicating haplotype sharing between these two taxa.

Host plants

Betula pubescens Ehrh. ssp. czerepanovii (N. I. Orlova) Hämet-Ahti (rearings and ex ovo rearing experiments by VV).

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland, Germany, Portugal, and Sweden.

Pristiphora sootryeni Lindqvist, 1955

Pristiphora sootryeni Lindqvist, 1955: 46. Holotype ♀ in TROM, not examined. Type locality: Småströmmen, Finnmark, Norway.

Similar species

Based on the external morphology, the most similar species are P. astragali, P. confusa, P. opaca, P. pusilla, P. staudingeri, and P. subopaca, from which it is best distinguished by the structure of the lancet (Fig. 45). The lancet has weak ctenidia (weak or well-developed in the others) and on the inner surface of the lancet there are small spiny pectines (or dentes semicirculares) that reach the sclerora (present also in P. astragali). However, differences from P. astragali are rather small. Morphologically, the subapical tooth of the claws tends to be larger, the apical serrulae of the lancet are longer, and the number of ctenidia on the lancet is larger than in P. astragali (Figs 43–44; Vikberg 2006). Male unknown.

Genetic data

Based on a COI barcode sequence of one confidently identified specimen from Kuusamo (Finland; DEI-GISHym80036), it belongs to the same BIN cluster as P. astragali (BOLD:AAL8292), which in the BOLD database includes two other unidentified specimens from Manitoba, Canada (Fig. 1). The nearest neighbour (BOLD:AAL8277) is 2.40% different. BIN cluster BOLD:AAL8277 might include P. astragali, as one of the included specimens in BOLD database was identified by Matti Viitasaari as “Pristiphora nr. astragali”. Amplification of TPI failed.

Host plants

Oxytropis campestris (L.) DC. (Lindqvist 1973; Vikberg 2006).

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland.

Pristiphora staudingeri (Ruthe, 1859)

Nematus Staudingeri [sic!] Ruthe, 1859: 306–307. Lectotype ♀ (designated by Vikberg 1978) in NMW, examined. Type locality: Iceland.

Pristiphora circularis Kincaid, 1900: 350. Holotype ♀ (USNMENT00778165) in USNM, not examined. Type locality: Popof Island, Alaska, USA.

Pristiphora hyperborea Malaise, 1921: 11. Lectotype ♀ (NHRS-HEVA000003650; designated by Vikberg 1978) in NHRS, examined. Type locality: Torne Träsk, Torne Lappmark, Sweden.

Pristiphora asperlatus Benson, 1935: 35–38. Holotype ♀ in BMNH, not examined. Type locality: Mount Braeriach, Inverness, Scotland, United Kingdom.

Similar species

Based on the external morphology, the most similar species are P. astragali, P. confusa, P. luteipes, P. opaca, P. pusilla, P. sootryeni, and P. subopaca. The combination of usually strongly coriaceous sculpture on the mesepisternum (Fig. 20), the habitat (arctic or subarctic), and the structure of the lancet (absence of small spiny pectines or dentes semicirculares and well developed ctenidia; Figs 73–76) or penis valves (Figs 97–100, 102) should usually enable distinction of the species from other similar species. Vikberg (1978) treated P. hyperborea Malaise tentatively as a separate species, but no characters distinguish it unambiguously from P. staudingeri. The small differences in lancets (Figs 73–76), penis valves (Figs 97–100, 102) and the sculpture of the mesepisternum most likely represent within species variation and therefore we treat P. hyperborea as a synonym of P. staudingeri as suggested by Lindqvist (1953). In addition, penis valves and lancets cannot be distinguished from P. luteipes and P. beaumonti (see under P. luteipes) (Figs 60–61, 101, 103), which can have a completely smooth mesepisternum (Fig. 19) and can be extremely pale (Fig. 13). Because of the black metafemur, females of P. staudingeri can easily be distinguished from P. luteipes (completely yellow metafemur; Fig. 23), but two studied Swedish specimens (Jämtland County at an altitude 900 m) had an apically slightly yellow (W10115) or even apically half yellow metafemur (W10105), weakening the distinction between these taxa.

Genetic data

Based on COI barcode sequences, belongs to the same BIN cluster (BOLD:AAG3568) as P. aphantoneura, P. bifida, P. confusa, P. opaca, P. pusilla, and P. subopaca (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. It is not clear if nuclear TPI sequences allow better identification of P. staudingeri compared to COI barcode sequences, mainly because the identity of the male specimen DEI-GISHym80049 (Fig. 2) is uncertain. According to TPI sequence, this male from Sweden is closer to P. luteipes (males of which are not known from northern Europe for certain) than to P. staudingeri (Fig. 2), but morphological characters and collecting locality (Härjedalen at an altitude of 840 m) does not allow for certain identification. In addition, COI barcode of DEI-GISHym80049 is identical to one of the P. staudingeri specimens (Fig. 1).

Host plants

Salix herbacea L. and S. phylicifolia L. (Vikberg 1978).

Distribution and material examined

Western Palaearctic, Nearctic. Specimens studied are from Finland, France, Great Britain, Iceland, Norway, Sweden, and Switzerland. The species should be removed from the fauna of Denmark. Publications (e.g. Taeger et al. 2006) mentioning this species from Denmark are based on misinterpretation of Nielsen and Henriksen (1915), who actually recorded P. albitibia under the name P. staudingeri, as evidenced by the mentioned hostplant, Vicia cracca.

Pristiphora subopaca Lindqvist, 1955

Pristiphora subopaca Lindqvist, 1955: 41–42. Holotype ♀ (http://id.luomus.fi/GL.5202) in MZH, examined. Type locality: Munksnäs, Uusimaa, Finland.

Pristiphora coniceps Lindqvist, 1955: 39–40, syn. n. Holotype ♀ (http://id.luomus.fi/GL.5207) in MZH, examined. Type locality: Pihtipudas, Central Finland, Finland. Note. The male paratype (http://id.luomus.fi/GL.5208) is not conspecific with the holotype female and belongs to P. melanocarpa; therefore most records of P. coniceps in the literature based on the penis valve belong to that species.

Pristiphora brunniapex Lindqvist, 1960: 37–38, syn. n. Holotype ♀ in MZH, examined. Type locality: Pisa, Rovaniemi, Finland.

Similar species

Based on the external morphology, the most similar species are P. albitibia, P. confusa, P. opaca, P. pusilla, and P. sootryeni. The species is best distinguished through the structure of male penis valve (Figs 91–92). Unfortunately, it is rather difficult to separate females from P. confusa and P. opaca as the differences in the lancets are small (Figs 6269). Apical serrulae are perhaps less protruding and longer (Figs 66–69) than in P. confusa (Figs 62–63) and the basal part of the tangium lacks a fold that is present in P. opaca (Figs 64–65). Externally, the pterostigma is uniformly yellow (Fig. 27) unlike in P. confusa and P. opaca, in which the pterostigma is basally dark brown and apically brown (Fig. 28). In addition, the claws of P. subopaca tend to have a larger subapical tooth (Fig. 32) than in P. opaca (Fig. 31). Among the males, the most similar penis valves are of P. confusa and P. pusilla. The ventro-apical spine is bent more strongly and the pseudoceps is broader (Figs 91–92) than in P. confusa (Figs 89–90). Compared to P. pusilla (Figs 93–94), the ventro-apical spine is bent less strongly and the dorsal depression in the middle of pseudoceps is less distinct, which is clear only when compared to the left penis valve of P. pusilla (Fig. 93). The holotype of coniceps Lindqvist does not differ in any significant way from the holotype of subopaca Lindqvist. The characters mentioned in the structure of the head and thorax for coniceps in the original description (Lindqvist 1955), that are supposed to differentiate this species from others in the ruficornis group, are minute and unreliable. The characters that help in species identifications in closely related species (colour of pterostigma and antennae, degree of coriaceous sculpture of mesepisternum, size of subapical tooth of claws, and the structure of the lancet) are not different between the holotypes of coniceps and subopaca. The host (Salix) mentioned for coniceps in the original description (Lindqvist 1955) and by Kangas (1985) (as Salix caprea L.) also fits with the data recorded for P. subopaca (Lindqvist 1965; Kangas 1985). Consequently we treat coniceps as a synonym of subopaca. We also treat brunniapex Lindqvist as a rare colour form (only the holotype and one additional female are known to us) of subopaca Lindqvist, because the only difference is that brunniapex has a pale tip of the abdomen (terga 7–10 or 8–10; Figs 10, 12). Based on the second known specimen (DEI-GISHym20899, deposited in MZH) reared by J. Perkiömäki from Salix sp. (near Helsinki, Finland), we can say that the host is not different from subopaca either. Although the lancet of brunniapex cannot be distinguished from P. aphantoneura, P. luteipes and P. staudingeri, these species can be separated from subopaca-brunniapex by having different host (Lathyrus pratensis for P. aphantoneura), yellow metafemur (P. aphantoneura and P. luteipes), or as in P. staudingeri usually strongly coriaceous sculpture of mesepisternum and different habitat (arctic or subarctic).

Genetic data

Based on COI barcode sequences, P. subopaca belongs to the same BIN cluster (BOLD:AAG3568) as P. aphantoneura, P. bifida, P. confusa, P. opaca, P. pusilla, and P. staudingeri (Fig. 1). The nearest neighbour (BOLD:AAQ2302, P. armata and P. leucopus) is 2.76% different. Only one TPI sequence is available, which can be distinguished from other species (Fig. 2).

Host plants

Salix caprea L. (Lindqvist 1965; Kangas 1985) and S. phylicifolia L. (Lindqvist 1965).

Distribution and material examined

Western Palaearctic. Specimens studied are from Finland and Sweden.

Discussion

Taxonomy of the species belonging to the ruficornis group as defined here (Fig. 1) has hitherto been rather complicated, and there has not been a review of all the species involved. The main questions have been, how many species there are, how to identify them, and association of males and females. For northern Europe, we identified which species are well supported (most) and should be recognised and which ones require more detailed studies (e.g. host plant choice experiments and sequencing of more nuclear DNA data) to decide their validity. The species pairs that are not well supported are P. aphantoneura-P. luteipes, P. armata-P. leucopus, and P. melanocarpa-P. ruficornis, identification of which is difficult or not always possible. Although our limited genetic data is consistent with separation of P. luteipes from P. aphantoneura (Fig. 2), the limited sampling of specimens does not allow us to make any definite conclusions. There is no clear genetic support for separating P. leucopus from P. armata, nor P. melanocarpa from P. ruficornis. The separation of P. leucopus from P. armata is currently supported mainly by two biological differences: their different hosts, and the existence of seasonal morphs in the former, but not in the latter. Furthermore, the coloration of the larvae may be different (see above, under Introduction). However, the larval morphology of both species needs more detailed study. P. melanocarpa is separated from P. ruficornis only on minor morphological differences in the adults. Here too, the larvae require further study. Another issue not entirely solved involves P. luteipes, P. staudingeri, and P. beaumonti (North African taxon not treated here), because morphological characters used to distinguish them (colouration and sculpture of the mesepisternum) might be influenced by environmental factors rather than genetic ones, though our limited nuclear data indicates several separate lineages (Fig. 2). The other taxa treated here can be considered to be distinct species, although the evidence for treating P. astragali and P. sootryeni as separate species is currently relatively weak (basically based only on the differences in the structure of the lancet), as the males are unknown and nuclear DNA data are lacking.

Even if most of the species treated here can be considered distinct, their identification unfortunately remains relatively difficult. For reliable results, lancets and penis valves should be studied. Nevertheless, we hope that the current revision removes most of the previous confusion about species identities, their names and the association of females and males, as well as enabling more reliable and confident identification of the species. One further issue that is worth following up is the identity of the species in North America, as barcoding has revealed close connections to Northern Europe (there are many identical or nearly identical barcodes between the continents; Fig. 1), presumably via northern Eurasia. The only species that definitely belongs to the ruficornis group in the East Palaearctic or Oriental Regions, and which is not known in the West Palaearctic, is P. ribisi. However, the Pristiphora of these regions have not been intensively investigated.

Examination of most of the barcoded specimens from Europe revealed that most of the species within the Pristiphora ruficornis group cannot be unambiguously identified based on mitochondrial COI barcodes. Nevertheless, barcoding showed the presence of five well separated clusters within the ruficornis group, each containing a unique set of species (Fig. 1). This enables detection of at least some misidentifications. For example, specimens in BOLD identified as P. melanocarpa or P. ruficornis within the armata subgroup are almost certainly wrong and should be re-examined to check if they belong to P. armata, P. leucopus, or both. Another benefit of barcoding is placing unidentified specimens, which can reveal important specimens worthy of a closer look (for example new distributional records or new phylogenetic lineages). The inability of mitochondrial DNA to identify closely related species, even when there is enough variation (barcode differences around 2–3%), has been shown to be the case in several other sawfly groups (Linnen and Farrel 2007; Prous et al. 2011). This is perhaps not so surprising in the light of recent theoretical population genetic studies (Patten et al. 2015) that found biased introgression patterns of mitochondrial DNA in comparison to nuclear DNA in haplodiploid species (as is the case for Hymenoptera). This suggests that nuclear DNA might be more successful in identifying closely related species in these cases, as was found to be the case in Empria and Neodiprion (Linnen and Farrel 2007; Prous et al. 2011). Although our results for the ruficornis group based on one single-copy nuclear protein coding gene (TPI) are consistent with this observation (Fig. 2), the small number of specimens sequenced (due to poor quality DNA of most of the available samples, i.e. air-dried pinned specimens) does not at the moment allow us to propose that this particular nuclear gene is definitely better for species identification than COI barcodes. Additional studies based on more nuclear genes and more specimens from different sawfly groups are needed to decide which nuclear region might be useful for species identification of most sawflies.

Acknowledgements

The study was supported by the Swedish Taxonomy Initiative (contract number dha 153/2011). For loans and gifts of material, as well as giving advice and valuable information, we would like to thank Ruth Ahlburg, John Grearson, Christer Hansson, Erik Heibo, Mikk Heidemaa, Iiro Kakko, Manfred Kraus, Jean Lacourt, Ole Lønnve, Pekka Malinen, Henri Savina, Olga Schmidt, Stefan Schmidt, Andreas Taeger, Hege Vårdal, and staff of the Swedish Malaise Trap Project (particularly Mattias Forshage, Kajsa Glemhorn, Dave Karlsson and Pelle Magnusson). Valuable suggestions made by reviewers Akihiko Shinohara, David Smith, and Villu Soon helped to improve the manuscript.

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