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Revision of the European species of Euplectrus Westwood (Hymenoptera, Eulophidae), with a key to European species of Euplectrini
expand article infoChrister Hansson, Stefan Schmidt§
‡ Lund University, Lund, Sweden
§ Zoologische Staatssammlung München, Munich, Germany
Open Access

Abstract

The European species of Euplectrus Westwood are comprehensively treated for the first time, using a combination of morphological and DNA data (CO1, the barcode). Ten species are included, seven already described: E. bicolor (Swederus), E. flavipes (Fonscolombe), E. intactus Walker, E. liparidis Ferrière, E. maculiventris Westwood, E. nigriceps Ferrière, E. phthorimaeae Ferrière, and three new species: E. carinifer sp. n., E. geometricida sp. n., E. pallidigaster sp. n. To stabilize the nomenclature a neotype is designated for E. bicolor. Euplectrus intactus is removed from synonymy under E. bicolor and E nigriceps from synonymy under E. platyhypenae Howard, and both are re-established as valid species. Several host records are given and presented in a table, and new geographical records are introduced for previously described species. All host records are from exposed Lepidoptera caterpillars and the dominant host groups are Geometridae and Noctuidae. A key including all European species of tribe Euplectrini is presented. Prior to this paper the identification of European Euplectrus species has been difficult and misidentifications have probably been common. Existing host and geographical records in the literature must therefore be treated with great care.

Keywords

Neotype designation, reevaluation of synonymized species, new species, new host records, new geographical records, gregarious ectoparasitoids, cocoon spinning, Geometridae, Noctuidae, Platyplectrus, Metaplectrus

Introduction

Species of the genus Euplectrus are found all over the world, with most species occurring in tropical parts (e.g. Hansson et al. 2015). This genus currently includes 199 species, but only five of them are recorded from Europe (Noyes 2018). Even though it is a very small genus in Europe the confusion resulting from misidentifications of specimens, and the unresolved taxonomy and nomenclature on species level, have resulted in many erroneous geographical and biological records in the literature. Most European records, geographical as well as biological, have been attributed to E. bicolor Swederus, this is in spite of the unclear identity of this species (very short and bland original description and type material missing – see below). The results presented in this paper necessitate a check, and probable re-evaluation of several records in the literature regarding European Euplectrus. Species of Euplectrus are parasitoids of Lepidoptera caterpillars, some of which cause damage to cultivated plants, and the accurate identification of the parasitoids on these pests is essential for successful biological control efforts.

The first more comprehensive study of Euplectrus in Europe was by Ferrière (1941) who included four species: E. bicolor, E. nigriceps, E. cacoeciae, E. phthorimaeae, the three latter were described in the paper. Graham (1963) made an effort to sort out the British fauna of Euplectrus but due to unresolved morphological variation he expressed uncertainty regarding the identity of some names. He included three species, E. intactus Walker, E. maculiventris Westwood, and E. nigriceps in a key, but due to total lack of information for the type material of E. nigriceps he had doubts about the geographical status of that species. In addition, he mentioned two species: E. bicolor with uncertain identity because of lack of type material, and E. flavipes (Fonscolombe) that obviously did not occur in Britain but was regarded as a distinct species by Graham. Bouček and Askew (1968) synonymized E. maculiventris and E. intactus with E. bicolor. Zhu and Huang (2002) re-evaluated the status of E. maculiventris and removed it from synonymy, and later (2003) included E. bicolor, E. flavipes and E. maculiventris in their study of Euplectrus from China, and added E. liparidis Ferrière to the list of European species, a species that previously was known only from North Africa.

Due to previous difficulties with the identification of the species and the somewhat unclear nomenclatural situation only distributional and biological information for specimens examined here will be included in this paper.

Methods

Imaging

The SEM micrographs are from uncoated specimens and were done with a Hitachi SU 3500, using a backscatter detector. The colour images were made using a Canon camera equipment including an EOS 70D body, MP E-65 macro lens, and macro twin lite MT-24 EX. The camera was attached to a Cognisys stackshot macrorail system. The picture stacking was done with Helicon Focus version 6 software.

DNA sequencing

For DNA extraction, whole specimens were sent to the Canadian Centre for DNA Barcoding (CCDB) in Guelph, Canada, for DNA extraction and barcode sequencing, and subsequent recovery of vouchers for preparation and morphological study. A complete list of voucher specimens included in the revision is given in Suppl. material S1. DNA extraction, PCR amplification, and sequencing were conducted at the Canadian Centre for DNA Barcoding (CCDB) using standardised high-throughput protocols (Ivanova et al. 2006, deWaard et al. 2008, http://www.ibolproject.org/resources.php). The 658 bp target region, starting from the 5’ end of the mitochondrial cytochrome c oxidase I (COI) gene, includes the DNA barcode region of the animal kingdom (Hebert et al. 2003). The DNA extracts are stored at the CCDB. Specimens that were successfully sequenced are listed in Suppl. material S1. All specimen data are accessible in BOLD as a single citable dataset (dx.doi.org/10.5883/DS-EUPLEUR). The data include collecting locality, geographic coordinates, elevation, collector, one or more digital images, identifier, and voucher depository. Sequence data can be obtained through BOLD and include a detailed LIMS report, primer information, and access to trace files. The sequences are also available on GenBank (for accession numbers see Suppl. material S1).

Data analysis

Sequence divergence statistics were calculated using the Kimura two parameter model of sequence evolution (Kimura 1980). Barcode Index Numbers (BINs) were assigned by the BOLD system, representing globally unique identifiers for clusters of sequences that correspond closely to biological species (Ratnasingham and Hebert 2013). For BIN assignment, a minimum sequence length of 500 bp is required, and sequences between 300 and 500 bp can join an existing BIN but will not create or split BINs. In the present study, BINs were used to delineate Molecular Operational Taxonomic Units (MOTUs) prior to a detailed taxonomic study based on morphological characters. Sequences were aligned using the BOLD Aligner (amino acid-based hidden Markov models). The analyses are based on sequences with a minimum length of 500 bp and <1% ambiguous bases. Genetic distances and summary statistics were calculated using analytical tools in BOLD and are given as mean and maximum pairwise distances for intraspecific variation and as minimum pairwise distances for interspecific variations.

Abbreviations of morphological terms (Figs 3–6)

DO = largest diameter of one posterior ocellus; HE = height of eye in frontal view; HH = height of head; LC = length of scape; LP = length of petiole; LT = length of hind tarsus; LT1 – 4 = length of first – fourth tarsomere on hind leg; MS = malar space; OOL = the distance between eye and posterior ocellus; PM = length of postmarginal vein; POL = the distance between posterior ocelli; POO = the distance between posterior ocelli and occipital margin; ST = length of stigmal vein; TS1 = length of longest hind tibial spur; TS2 = length of shortest hind tibial spur; WE = width of eye; WF = width of frons, in frontal view the largest distance between eyes; WH = width of head, measured across the widest part; WM = width of mouth opening; WP = width of petiole, measured across widest part; WS = width of scape, measured across widest part. Lower face as defined by Gibson (1997), i.e. the part below an imaginary line from eye to eye touching ventral edge of toruli.

Museum acronyms

MZH Finnish Museum of Natural History, Zoological Museum, Helsinki, Finland.

MZLU Museum of Biology (Entomology), Lund University, Lund, Sweden.

NHM the Natural History Museum, London, United Kingdom.

NHRS the Natural History Museum, Stockholm, Sweden.

OUMNH Oxford University Museum of Natural History, United Kingdom.

SMTP Swedish Malaise Trap Project, Station Linné, Ölands Skogsby, Sweden.

VV private collection of Veli Vikberg, Turenki, Finland.

ZSM Zoologische Staatssammlung München, Germany.

Results

Key to the European species of Euplectrini (i.e. Eulophinae species with 1–2 long spurs at apex of hind tibia)

1 Scutellum without lateral grooves (e.g. Fig. 48) (genus Euplectrus) 2
Scutellum with lateral grooves (Figs 57, 58) 13
2 Head completely dark (Figs 44, 45) Euplectrus nigriceps Ferrière
Head with at least clypeal area pale (e.g. Figs 10, 27) 3
3 Entire frons below level of toruli, including part below eye, white to yellowish-white, in males pale area reaches the eye and usually covers part of frons lateral to toruli (e.g. Figs 14, 31), in female pale area leaves at most a narrow dark stripe close to eyes (e.g. Fig. 30) 4
Frons below toruli with pale area smaller (e.g. Figs 9, 10), pale area never reaches eyes – in some males it almost reaches eyes but leaves a dark stripe close to eyes (Fig. 12) and never reaches up on surface lateral to toruli 7
4 Female 5
Male 6
5 Without groove between dorsellum and scutellum (Fig. 37); female gaster with pale area in anterior part as a round spot about as wide as ½ the width of gaster (Fig. 37) Euplectrus liparidis Ferrière (♂ unknown)
With a groove between dorsellum and scutellum (Fig. 52); pale area on female gaster with anterior ½ narrow, narrower than width of petiole, and with posterior ½ expanding and as wide as ½ the width of gaster (Fig. 19) Euplectrus geometricida sp. n.
6 Scape 2.8–3.0× (mean = 2.86, n=10) as long as wide (Fig. 14) Euplectrus maculiventris Westwood
Scape 2.0–2.5× (mean = 2.24, n=10) as long as wide (Fig. 15) Euplectrus geometricida sp. n.
7 Midlobe of mesoscutum with a distinct and complete median carina (Figs 51, 53), carina sometimes weak or missing close to posterior margin of pronotum and sometimes replaced by a groove close to scutellum; female gaster with apex pale (Figs 22, 35) 8
Median carina on midlobe of mesoscutum missing (e.g. Fig. 49) or incomplete (e.g. Fig. 48); female gaster with apex dark (Fig. 8) or pale (Figs 25, 26) 9
8 Female with pale area in anterior ½ of first gastral tergite large and with narrow brown margins, margins about ½ as wide as width of petiole (Fig. 35); male gaster with pale area reaching margin in posterior part thus interrupting lateral brown margin (Fig. 13) Euplectrus flavipes (Fonscolombe) (♀, ♂)
Female with pale area in anterior ½ of first gastral tergite smaller and with wider brown margins, margins on average at least as wide as width of petiole (Fig. 22); male gaster with evenly wide brown uninterrupted margins in anterior ½ (Fig. 16) Euplectrus carinifer sp. n. (♀, ♂)
9 Female gaster dark yellowish-brown with anterolateral corners dark brown (Fig. 25), in some specimens also with a dark brown round spot posteromedially (Fig. 26); male scutellum with weak and predominantly ±isodiametric meshes Euplectrus pallidigaster sp. n. (♀, ♂)
Female gaster predominantly dark brown (Figs 8, 29, 32); male scutellum with ± elongate meshes, thus appearing more striate than in alternate 10
10 Posterior part of midlobe of mesoscutum wide (Figs 49, 56), ratio width base of midlobe (a)/width base of one sidelobe (b) = 0.80±0.048 (females), 0.80±0.054 (males); midlobe of mesoscutum without median line indicated (Figs 49, 56) Euplectrus intactus Walker (♀, ♂)
Posterior part of midlobe of mesoscutum narrow (e.g. Figs 48, 55), ratio width base of midlobe (a)/width base of one sidelobe (b) = 0.57±0.070 (females), 0.55±0.070 (males); median line on midlobe of mesoscutum usually indicated by a median groove or median carina in posterior ½ (Figs 48, 55), sometimes by a weak carina in anterior ½, in some specimens median line indicated just through a change in the reticulation 11
11 Female with pale area on lower frons with upper-lateral part drawn out towards eye and almost reaches eye (Fig. 30); scutellum with isodiametric meshes (Fig. 50) (males key out under couplet 6) Euplectrus maculiventris Westwood
Female with pale area on lower frons not drawn out laterally (Fig. 10), scutellum with elongate or isodiametric meshes, or males 12
12 Reticulation on posterior part of scutellum with elongate meshes, this part of scutellum thus appearing striate (Fig. 48) Euplectrus bicolor (Swederus) (♀, ♂)
Reticulation on posterior part of scutellum with ±isodiametric meshes (Fig. 40) E. phthorimaeae Ferrière (♀, ♂)
13 Hind tibia with one spur at apex Metaplectrus szepligetii (Erdös) (♀, ♂)
Hind tibia with two spurs at apex (as in Fig. 36) (genus Platyplectrus) 14
14 Scutellum smooth and shiny, without reticulation (Fig. 57) 15
Scutellum reticulate (Fig. 58) 16
15 Petiole about twice as long as wide; flagellomeres long in both sexes, e.g. funicular 2&3 in female both 1.3× as long as wide (Fig. 62), in male 1.1 and 1.3× respectively Platyplectrus laeviscuta (Thomson) (♀, ♂)
Petiole transverse; flagellomeres short in both sexes, e.g. funicular 2&3 in female both 0.8× as long as wide (Fig. 61), in male 1.0× (Erdös 1966) Platyplectrus bouceki (Erdös) (♀, ♂)
16 Occipital margin with a sharp carina (Fig. 59) Platyplectrus pannonica (Erdös) (♀, ♂)
Occipital margin rounded (Fig. 60) Platyplectrus chlorocephala (Nees) (♀, ♂)

Genus Euplectrus Westwood

Euplectrus Westwood, 1832:128. Type species E. maculiventris Westwood, 1832:128, by monotypy.

Diplectron Dahlbom, 1857:292. Type species Pteromalus bicolor Swederus, 1795:204, designated by Gahan and Fagan 1923:46. Synonymized by Dalla Torre 1898:74.

Pachyscapha Howard, 1897:159. Type species P. insularis Howard, 1897:159, by monotypy. Synonymized by Ferrière 1941:38.

Rekabia Cameron, 1904:65. Type species R. testaceipes Cameron, 1904:66, by monotypy. Synonymized by Kerrich 1974:636.

Heteroscapus Brèthes, 1918:9. Type species H. ronnai Brèthes, 1918:10, by monotypy. Synonymized by De Santis 1980:153.

Heteroscapiscus Ghesquière, 1946:370. Replacement name for Heteroscapus Brèthes.

Biology

Species of Euplectrus are all parasitoids on Lepidoptera caterpillars that live exposed on their food plant and their life-history is very interesting, including some unique features (e.g. Hansson et al. 2015). Prior to egg-laying the female wasp injects a substance that prohibits further ecdysis by the host caterpillar – moulting would shed the parasitoid eggs/larvae that are attached to the cuticle. The female wasp then lays her eggs on the host, usually several per host and if the host is large several hundred eggs may be deposited, but occasionally if the host is small, only one egg per caterpillar is laid. The eggs are anchored in the cuticle of the caterpillar, usually on the dorsum. When the wasp larvae hatch they will remain attached to the same spot where the eggs were anchored (Fig. 1), using the egg shell as a pad to which they attach themselves to the host and they are difficult to scrape off. After completed development the wasp larvae pupate on, under or beside the (now) dead host, but before they pupate they spin a loose cocoon (Fig. 2), a feature that is unique within the entire Chalcidoidea. The spin is produced by modified Malpighian tubules and is secreted through the anal opening. The adult wasps emerge after a few days, the number of days depend on the ambient temperature and Euplectrus species.

Figures 1–2. 

Euplectrus bicolor (Swederus): 1 larvae on caterpillar of Orthosia sp. (Lepidoptera: Noctuidae) 2 pupae with spin threads. Photo courtesy Špela Modic.

Figures 3–6. 

Euplectrus terminology, schematic illustrations: 3 head in frontal view 4 vertex 5 apex of hind leg with tibial spurs and tarsus 6 part of left forewing. For explanation of abbreviations see text above “Abbreviations of morphological terms”.

Species treatments

Euplectrus geometricida sp. n.

Figures 15, 17–19, 52

Material

Holotype female labeled “CZECH REPUBLIC: Mikulcice, 48,808N, 17,094E, 169m, 21-May-2013, M. Volf, Sample BC-ZSM-HYM-23872-E10, CO1-5p 652(0)bp BOLD: ACU3230”, from Colotois pennaria on Carpinus betulus, in ZSM. Paratypes (133♀ 88♂): CZECH REPUBLIC (38♀ 54♂, in MZLU, NHM, ZSM): 1♀ 2♂ with same label data as holotype; following from same locality as holotype but collected 22-May-2013 from Agriopis marginaria on C. betulus (1♀), 23-May-2013 from A. marginaria on C. betulus (2♀ 1♂), 27-May-2013 from Operophtera brumata on C. betulus (2♂), 29-May-2013 from Alsophila aescularia on C. betulus (2♀), 31-May-2013 from C. pennaria on C. betulus (1♂), A. aescularia on C. betulus (1♂), 01-June-2013 from A. aescularia on C. betulus (1♀); “CZECH REPUBLIC: obora Soutok, Lanzhot, 48,69N, 16,945E, 165m, 08-May-2014, P. Drozd”, from A. marginaria on C. betulus (13♀ 16♂), A. aurantiaria on C. betulus (7♀ 2♂), A. aurantiaria on Tilia cordata (1♀), Epirrita dilutata on C. betulus (3♀), Phigalia pilosaria on C. betulus (2♀ 2♂), unidentified Geometridae on C. betulus (2♀ 18♂); following from same locality as previous but collected 16-May-2013, from Agriopis sp. on C. betulus (1♂), 19-May-2013, from unidentified larva on C. betulus (2♂), O. brumata on C. betulus (2♂), 04-May-2014, from Phigalia pilosaria on Acer campestre (2♂), 05-May-2014, from A. marginaria on C. betulus (1♀), O. brumata on Quercus cerris (1♀ 2♂), 09-May-2014, from A. aurantiaria on T. cordata (1♀). FINLAND (44♀ 7♂, in MZH, MZLU): 1♀ “FINLAND, Ab: Lohjan kunta, 6693:334, 21.6.1991, M. Koponen leg.”; 1♀ “FENNIA: EH, Hämeenlinna, 1978, P. Somerma leg.”; 2♀ “SUOMI: EH, Janakkala, 6754:369, 19.8.1979, M. Koponen leg.”; 1♂ “SUOMI: EH, Janakkala, 6760:369, 24.8.1980, M. Koponen leg.”; 1♀ “SUOMI: EH, Lammi, 6773:394, 19.9.1982, M. Koponen leg.”; 1♀ “SUOMI: ES, Mikkelin mlk. 6830:501, 7.8.1989, M. Koponen leg.”; 3♀ “SUOMI: ES, Ristiina, 6830:502, 5.8.1978, M. Koponen leg.”; 1♂ “SUOMI: ES, Ristiina, 6826:502, 2.8.1981, M. Koponen leg.”; 1♀ “SUOMI: KP, Vimpeli, 7015:346, 18.8.1982, M. Koponen leg.”; 1♀ “SUOMI: PH, Rautalampi, 6961:484, 17.7.1983, M. Koponen leg.”; 1♀ “SUOMI: PP, Pello, 7248:372, 5.7.1982, M. Koponen leg.”; 1♀ “SUOMI: PP, Yli-Ii, 7248:444, 21.7.1980, M. Koponen leg.”; 1♀ “SUOMI: PP, Ii, 7249:424, 11.8.1982, M. Koponen leg.”; 1♀ “FINLAND, Sa, Ristiina, 6824:503, 10.7.1993, M. Koponen leg.”; 1♀ “SUOMI: U. Helsinki, 6682:383, 6.9.1980, M. Koponen leg.”; 1♀ “SUOMI: U. Hyvinkää, 6716.374, 2.6.1979, M. Koponen leg.”; following from same locality as previous but collected 14.v.1983 (1♀), 19.vi.1983 (1♀), 31.vii.1984 (1♀); 1♀ “SUOMI: U. Nurmijärvi, 6718:381, 17.6.1979, M. Koponen leg.”; 1♀ “SUOMI: U. Nurmijärvi, 6712:370, 11.6.1989, M. Koponen leg.”; 1♀ “SUOMI: U. Nurmijärvi, 8713:386, 28.7.1989, M. Koponen leg.”; 1♂ “SUOMI: U. Nurmijärvi, 6710:381, 1.9.1993, M. Koponen leg.”; 1♂ “SUOMI: V, Vihti, 6717:366, 17.8.1975, M. Koponen leg.”; 1♀ ”Nystad, Hellén” ”29.7.1923”; 1♀ ”Nystad, Hellén” ”26.8.1914”; 1♀ ”Nystad, Hellén” ”25.8.1923”; 1♀ ”FENNIA, Hammarland, 3.8.1953, W. Hellén”; 1♀ ”Sibbo, Norrkulla, 8-11.8.57, Hellén”; 1♀ ”Suomi V Turku, 10.10.1949, E.K. Lahtiperä leg.”; 1♀ ”Kivinebb, K. Ehnberg”; 1♀ ”Fennia, Bobäck, Hellén”; 1♀ ”Fennia, Luumäki, Hellén”; 1♀ ”Fennia, Oa, Maxmo, 4-14.6.46, Hellén”; 1♀ ”Hauho, Hiiriniemi, 14.8.1935, Hellén”; 1♀ ”Hauho, 1935, Hellén”; 1♀ ”Keuru, 14.8.1928, Hellén”; 2♀ ”Terijoki, 25.8.1927, Hellén”; 1♀ ”Parikkala, Laurila, 15.7.1940, Hellén”; 1♀ ”Parikkala, Hellén”; 1♀ ”Vammeljoki, 4.8.1927, Hellén”; 1♀ ”Fennia, Taipalsaari, Hellén”; 1♂ ”P. Pirkkala, Grönblom, 11/7 1913”; 1♀ ”Finland, AI, Lemland, Flaka, 1956, Vaselius”; 1♂ ”Fennia, Lemland, 5.8.53, W. Hellén”; 1♂ ”Fennia, Nurmes, 21.7.1939, A. Saarinen”; 1♀ ”Tvärminne, Storå, Storkärret, medio 7.35, e.l. Agr. subr”, from Agrotis segetum. FRANCE (20♀ 12♂, in NHM, leg. M.W.R. de V. Graham): 2♂ “FRANCE: Auvergne, nr. Les Essards (oakwood), 7.viii.1973”; 4♀ “FRANCE: Auvergne, S. bank of river Rhone, nr Essards, 7.viii.1973”; 1♀ “FRANCE: B. du Rhone, Fonscolombe (1), 24.vii.1984”; following from same locality but collected 2.vii.1980 (1♂), 21.vi.1982 (1♂), 10.viii.1983 (1♂), 10.vii.1986 (2♀), 14.viii.1986 (1♂); 1♀ “FRANCE: B. du Rhone, Rognes, 13.vii.1978”; 1♀ “FRANCE: B. du Rhone, nr. Rognes, 24.vii.1974”; 3♀ 4♂ “FRANCE: Drôme, Le Poet-en-Percip (2), 21.viii.1990”; 1♀ “FRANCE: Drôme, Montagne de Bluye, 18.vii.1974”; 1♂ “FRANCE: Haute-Loire, nr. Lubilhac, 20.vii.1977”; 1♀ “FRANCE: Provence, Alpes de Haute, 2km N of Reillane, 21.vii.1978”; 1♀ “FRANCE: Provence, Alpes de Haute, nr. Reillane, 17.vii.1978”; 1♂ “FRANCE: Var: St. Tropez, 6.vi.1980, Bouček”; 1♀ “FRANCE: Vaucluse, nr Bèdoin (2), 13.vii.1980”, 1♀ from same locality but collected 19.vii.1983; 1♀ “FRANCE: Vaucluse, nr Col de Murs, 27.vii.1975”; 1♀ “FRANCE: Vaucluse, Mt. Ventoux, Massif des Cèdres, 25.viii.1975”; 1♀ “FRANCE: Vaucluse, Sérignan, 29.6.1977”. ITALY (1♂): “PIEMONTE, Castel, D.Bosca, 12.viii1954, A. Goidanich leg” (NHM). THE NETHERLANDS (1♀): ”NETHERLANDS, Gelderland, Ede, Edense Heide, 52.056N, 5.7E, 30m, 09-Aug-2005”, from Anarta myrtilli (ZSM). POLAND (3♂): ”POLAND, Dybki, Mazovia, 52.7333N. 21.7166E, 108m, 19-May-2016, M. Shaw” (ZSM). ROMANIA (1♀): “Romania: Iaşi, Bârnova Forest, nr Slobozia, 47°00'41"N, 27°36'11"E, 290m, 4.vii.2011, J.S.Noyes” (NHM). SWEDEN (20♀ 10♂): 1♀ “Bohuslän, Ljung, Lyckorna, Bo Tjeder, 25/6 -46” (MZLU); 1♀ “Lycksele Lappmark, Vilan, 20.7.1981, K.-J. Hedqvist” (NHM); 2♀ “Lycksele Lappmark, Tärna, 3.8.1956, K.-J. Hedqvist” (NHM); 1♂ “Norrbotten, Haparanda, 23.7.66, A. Sundholm” (MZLU); 1♂ “Skåne, Åhus, 14.7.1957, leg. K.-J. Hedqvist” (NHM); 1♀ 5♂ (one male without head) on same pin ”Skåne, Vånga, utkl. 1/7 06” (MZLU); 1♀ “S: Småland, Växjö, Åryd, 3.VII.1989, leg. R. Danielsson (DAYS)” (MZLU); 1♀ “Södermanland, Röm., 1937, A.J.” (MZLU); 1♀ “SWEDEN: Södermanland, Haninge kn, Tyresta, 59.107N, 18.138E, 18.vi.2004, SMTP” (SMTP); 1♀ “SWEDEN: Södermanland, Haninge kn, Tyresta, Urskogsslingan, 59.10N, 18.14E, 28.1–28.iv.2004, SMTP” (SMTP); 1♀ ”Södermanland, Tungelsta, 13.6.1957, B. Hansson”, from Angerona prunaria (NHM); 1♂ “Runmarö, Geometrid, 8.1916” “F.N.m” [=Frithiof Nordström] (MZLU); 1♀ “SWEDEN: Uppland, Älvkarleby kn, Båtfors, 60°27'38.3"N, 17°19'4.1'E, 26.viii-9.ix.2003, SMTP” (SMTP); 1♀ ”Uppland, Frösunda, 21.x.1977, leg. K.-J. Hedqvist” (NHM), following from same locality but collected 24.8.1973 (1♂), 29.7.1977 (1♂) (NHM); 1♀ 1♂ ”Uppland, Älvkarleby, Komossen, Kl. 15.6.1981, Nils Ryrholm” ”Ur larv av Cleora repandata”, from Alcis repandata (NHM); 1♀ “SWEDEN: Värmland, Ransäter, Rudstorp, 59.46N, 13.28E, 7–15.vii.2005, SMTP” (SMTP); 1♀ “SWEDEN: Värmland, Munkfors kn, Ransäter, Ransberg herrgård, 59.47N, 13.25E, 12.ix.2005–19.ii.2006, SMTP” (SMTP); 1♀ “SWEDEN: Västerbotten, Vindelns kn, Svartbergets försökspark, 64.138N, 19.471E, 22.ix.2003, SMTP” (SMTP); 1♀ “SWEDEN: Västerbotten, Vindelns kn, Kulbäckslidens trail park, 64°09'16.2"N, 19°35'35.5"E, 1–22.ix.2003, SMTP” (SMTP); 1♀ ”Västerbotten., Hällnäs, 20.9.1956, K.-J. Hedqvist” (NHM); 1♀ ”Ångermanland, Mjällom, 28.7.1989, K.-J. Hedqvist” (NHM); 1♀ “Sweden: Öland, Jordtorpsåsen, Kvarnbackarna, 56°40'44.3"N, 13°34'51.0"E, 27.vii.2015, C. Hansson” (MZLU); 1♀ ”Östergötland., Ändebol, 1–4.9.1955, K.-J. Hedqvist” (NHM). SWITZERLAND (1♀): ”Helvetia, umgb Aarau, 25.v.1926” (NHM). UNITED KINGDOM (9♀ 1♂, in NHM, leg. M.W.R. de V. Graham): 2♀ “ENGLAND: Berks., Wytham Wood (2), 1.ix.1959”, following from same locality but collected 18.vii.1958 (2♀), 25.vii.1958 (3♀); 1♀ “ENGLAND: Bucks., Hell Coppice (5), nr Oakley, 24.vi.1958”; 1♂ “ENGLAND: Cambs., Peterborough, Castor Hanglands, NNR”; 1♀ “ENGLAND: Oxon, Otmoor (3), 12.viii.1955”.

Diagnosis

Entire frons below level of toruli white to yellowish white, including part below eye (Figs 17, 18), some specimens with a very narrow dark stripe close to eyes; male scape 2.0–2.3× as long as wide; reticulation on median part of scutellum with elongate meshes (Fig. 52); with a groove between scutellum and dorsellum (Fig. 52).

Figures 7–16. 

Euplectrus spp.: 7–12 E. bicolor (Swederus) 7–9 neotype, female 7 habitus lateral 8 habitus dorsal 9 head frontal 10 non-type female, head front-lateral 11 head frontal, male 12 head front-lateral, male 13 E. flavipes (Fonscolombe), gaster dorsal, male 14–15 head including scape lateral, male 14 E. maculiventris Westwood 15 E. geometricida sp. n. 16 E. carinifer sp. n., gaster dorsal, male.

Figures 17–26. 

Euplectrus spp.: 17–19 E. geometricida sp. n., paratypes 17 head frontal, female 18 head frontal, male 19 gaster dorsal, female 20–22 E. carinifer sp. n., paratypes 20 head frontal, female 21 head frontal, male 22 gaster dorsal, female 23–26 E. pallidigaster sp. n., paratypes 23 head frontal, female 24 head frontal, male 25 gaster dorsal, female 26 gaster dorsal, female.

Description

(holotype female). Length of body 2.4 mm, female paratypes 1.9–2.4 mm. Antenna with scape yellowish-white with apical ⅓ yellowish-brown, pedicel and flagellum yellowish-brown. Mandibles and palpi yellowish-white. Head black, lower face yellowish-white, reaching to eyes and also below eyes (Fig. 17). Frons smooth, medially with a reticulate band reaching from eye to eye; close to eyes with scattered setae in lower ½ (Fig. 17). Vertex smooth and shiny. Occipital margin with a carina behind ocellar triangle.

Mesosoma black and shiny; midlobe with raised and strong reticulation, meshes isodiametric, midline on midlobe of mesoscutum indicated by a carina (Fig. 52), carina sometimes replaced by a change in the reticulation in posterior ⅓. Scutellum 1.0× as long as wide; with strong reticulation, meshes elongate (Fig. 52). Dorsellum with a deep groove along anterior margin (Fig. 52), groove medially 0.2× as long as length of dorsellum. Propodeum smooth and shiny (Fig. 52); anteromedially with a semicircular cup that is strongly raised in posterior part; propodeal callus with 19 setae. Legs yellowish-white, except yellowish-brown hind coxa and hind femur. Forewing: costal cell with two rows of setae on ventral surface, and margin with six setae close to marginal vein; with 15 admarginal setae.

Gaster dark brown with an inverted T-shaped white area in anterior ½ (Fig. 19).

Ratios. HE/MS/WM = 1.8/1.0/1.1; POL/OOL/POO = 9.7/4.3/1.0; OOL/DO = 1.4; WE/WF/WH/HH = 1.0/2.1/3.9/2.8; WH/WT = 1.0; PM/ST = 1.8; TS1/TS2/LT/LT1/LT2/LT3/LT4 = 4.6/3.1/7.4/2.4/1.4/1.0/1.9; LP/WP = 0.9; MM/LG = 1.3.

Male. Length of body 1.7–2.4 mm. Scape white, 2.0–2.3× as long as wide, widest medially, with sensory pores along entire ventral margin, sensory area white. Gaster with anterior ½–⅔ white with narrow dark brown margins, posterior part dark brown. Otherwise similar to female.

Ratios. LC/WS = 2.0–2.3, LP/WP = 1.0.

Hosts

Geometridae: Agriopis aurantiaria (Hübner) on Carpinus betulus and Tilia cordata, Agriopis marginaria (Fabricius) on C. betulus, Alcis repandata (L.), Alsophila aescularia (Denis & Schiffermüller) on C. betulus, Angerona prunaria (L.), Colotois pennaria (L.) on C. betulus, Epirrita dilutata (Denis & Schiffermüller) on C. betulus, Macaria brunneata (Thunberg) on Vaccinium myrtillus, Operophtera brumata (L.) on C. betulus and Quercus cerris, Phigalia pilosaria (Denis & Schiffermüller) on Acer campestre and C. betulus. Noctuidae: Agrotis segetum (Denis & Schiffermüller), Anarta myrtilli (L.), Orthosia opima (Hübner) on Vaccinium sp.

Distribution

Czech Republic, Finland, France, Italy, the Netherlands, Poland, Romania, Sweden, Switzerland, United Kingdom.

Etymology

Named after preferred target group, geometrid caterpillars. From the Latin suffix –cida, which means “killer”.

Genetic data

The species exhibits high levels of intraspecific variation, with a maximum of 11.6%, but a clear separation from the next neighbour, with a distance of 10.8% to the next neighbour species, E. carinifer (Fig. 63). The populations of the species segregate into several subclusters, each with its own Barcode Index Number. Four of the six subclusters were recorded from one country (Czech Republic) whereas two were recorded in two or more countries (Suppl. material S1). The presence of several distinct subclusters within the species indicates the presence of more than one species, but morphological analysis did not reveal any reliable characters for separating the species.

Euplectrus carinifer sp. n.

Figures 16, 20–22, 53

Material

Holotype female labelled “ CZECH REPUBLIC: Mikulcice, 48.808N, 17.094E, 169m, 21-May-2013, M. Volf, Sample BC-ZSM-HYM-27734-H05, CO1-5p 591 (0)bp BOLD: ACU2970”, from Amphipyra pyramidea on Carpinus betulus, in ZSM. Paratypes (2♀ 6♂): 1♂ with same label data as holotype (ZSM); following from same locality as holotype but collected 22-May-2013, from Orthosia cruda on C. betulus (2♂, MZLU, NHM), Perigrapha munda on C. betulus (2♀, MZLU, NHM), 24-May-2013 from P. munda on C. betulus (2♂, ZSM); 1♂ “CZECH REPUBLIC: obora Soutok, Lanzhot, 48,69N, 16,945E, 165m, 16-May-2013, P. Drozd”, from Carcina quercana on Acer campestre (ZSM); 3♀ “NETHERLANDS ZH Delft 30-VIII-2009 e.l., leg S. Wegh, ex Autographa gamma” (ZSM).

Diagnosis

Frons below level of toruli with pale area not extending laterally to the eye but with a wide dark stripe between pale area and eye, in both sexes (Figs 20, 21); midlobe of mesoscutum with a complete median carina (Fig. 53); with a narrow groove between scutellum and dorsellum (Fig. 53); female gaster with wide brown margins (Fig. 22).

Description

(holotype female). Length of body 2.0 mm, female paratypes 2.1–2.2 mm. Antennal scape yellowish-white with apical ½ yellowish-brown, pedicel and flagellomeres yellowish-brown. Mandibles and palpi yellowish-white. Head black with yellowish-brown clypeal area, pale area does not extend to eyes (Fig. 20). Frons smooth except a reticulate band closer to anterior ocellus than to toruli reaching from eye to eye, close to eyes with two rows of setae (Fig. 20). Vertex smooth and shiny. Occipital margin with a carina behind ocellar triangle.

Mesosoma black and shiny; midlobe with raised and strong reticulation, meshes ±isodiametric, midlobe of mesoscutum with a complete median carina (Fig. 53). Scutellum 1.0× as long as wide; with engraved reticulation, meshes small and isodiametric in median part and larger and elongate in lateral part, except smooth and shiny posterior margin (Fig. 53). Dorsellum with a narrow groove along anterior margin (Fig. 53), groove medially 0.3× as long as length of dorsellum. Propodeum smooth and shiny (Fig. 53); anteromedially with a triangular cup that is strongly raised in posterior part; propodeal callus with 12 setae. Legs pale yellowish-brown. Forewing: costal cell with two rows of setae on ventral surface, and margin with four setae close to marginal vein; with 14 admarginal setae.

Gaster dark brown, anterior ½ with a wide white stripe medially, stripe 2× as wide as width of petiole and expanding in posterior part, and with apex pale (Fig. 22).

Ratios. HE/MS/WM = 2.1/1.0/1.0; POL/OOL/POO = 6.3/2.9/1.0; OOL/DO = 1.4; WE/WF/WH/HH = 1.0/2.4/4.2/3.2; WH/WT = 1.0; PM/ST = 1.3; TS1/TS2/LT/LT1/LT2/LT3/LT4 = 3.5/2.2/7.2/2.0/1.6/1.0/2.0; LP/WP = 1.0; MM/LG = 1.2.

Male. Length of body 1.8–2.0 mm. Scape slightly enlarged, widest medially, with sensory pores along entire ventral margin. Similar to female except gaster with anterior ½ white with dark brown lateral margins, posterior ½ dark brown (Fig. 16).

Ratios. LC/WS = 2.8–3.0, LP/WP = 1.0.

Hosts

Noctuidae: Amphipyra pyramidea (L.) on Carpinus betulus, Autographa gamma (L.), Orthosia cruda (Denis & Schiffermüller) on C. betulus, Perigrapha munda (Denis & Schiffermüller) on C. betulus. Depressariidae: Carcina quercana (Fabricius) on Acer campestre.

Distribution

Czech Republic, the Netherlands.

Etymology

Named after complete median carina on midlobe of mesoscutum. From the Latin carina (=keel) and the suffix –fer (=carry).

Genetic data

The species consists of several subclusters, each assigned a different BIN by the BOLD system (Fig. 63) and a maximum intraspecific variation of 8.7%. Three of the subclusters occur in the Czech Republic, whereas the fourth was recorded from the Netherlands (Suppl. material S1). The high levels of intraspecific variation suggest the presence of more than one species, but in absence of reliable morphological characters for separating the MOTUs the populations are treated as a single species until more material from other regions and additional genetic data will allow a more thorough examination of the species status of each of the populations.

Euplectrus pallidigaster sp. n.

Figures 23–26, 54

Material

Holotype female labelled ”FRANCE: B du Rhone [possibly meaning “Bouches-du-Rhone], Fonscolombe, 20.vii.1979”, in NHM. Paratypes (20♀ 8♂): FRANCE (17♀ 8♂, in NHM, MZLU, leg. M.W.R. de V. Graham): following from same locality as holotype but collected 13.vii.1984 (1♀), 1.viii.1984 (1♀), 24.vi.1986 (1♀), 1.vii.1986 (1♀), 10.vii.1986 (1♀), 17.vii.1986 (1♀); 4♀ “FRANCE: Drome, Le Poet-en-Percip, (2), 3.viii.1990”, 1♂ from same locality but collected 21.viii.1990; 1♀ 2♂ “FRANCE: Gard, Causse de Blandas, (2), 8.viii.1984”; 1♀ ”FRANCE: Gard, Estezargues, nr. Remoulins, on elm leaf, 23.vi.1977”; 1♂ “FRANCE: Vaucluse, Beauregard, nr Gigondas, 19.ix.1989”; 1♀ “FRANCE: Vaucluse, nr Bèdoin, (1), 20.vii.1981”, following from same locality but collected 11.vii.1980 (1♀), 15.vii.1981 (2♂), 22.vii.1981 (1♀), 28.vii.1981 (1♂); 2♀ “FRANCE: Vaucluse, Mt Ventoux, Col de Perrache, (2), 6.viii.1979”; 1♂ “FRANCE: Vaucluse, Mt Ventoux, about Rte. de Perrache, (3), 11.viii.1976”. ITALY (2♀): 1♀ ”ITALY, Malcesine, 200–300m, 23.4.1977, leg. V. Vikberg” (MZH); 1♀ “ITALIA: Varazze, nr Genova, 4.IX.71, Bouček” (NHM). SPAIN (1♀): ”SPAIN: Barcelona, Calella d. Costa, VI.1971, Bouček” (NHM).

Diagnosis

Frons with clypeal area yellowish-brown (Figs 23, 24); scutellum with engraved reticulation, meshes ±isodiametric (Fig. 54); without a groove between scutellum and dorsellum (Fig. 54); female gaster dark yellowish-brown with anterolateral corners dark (Fig. 25), in some specimens also with a round black spot in medioposterior part (Fig. 26).

Description

(holotype female). Length of body 1.9 mm, female paratypes 1.6–2.6 mm. Antenna yellowish-brown, flagellomeres 4–6 slightly darker than scape and pedicel. Mandibles and palpi yellowish-white. Head black and shiny, with clypeal area yellowish-brown (Fig. 23). Face and median part of frons smooth, remaining part of frons with weak reticulation, close to eyes with two rows of setae (Fig. 23). Vertex smooth and shiny. Occipital margin with a carina behind ocellar triangle.

Mesosoma black and shiny; midlobe with raised and strong reticulation, meshes slightly transverse, midlobe of mesoscutum with a weak median groove in posterior ⅓ (Fig. 54). Scutellum 1.0× as long as wide; with engraved reticulation, meshes slightly elongate, except smooth and shiny posterior margin (Fig. 54). Without groove between scutellum and dorsellum (Fig. 54). Propodeum smooth and shiny medially, with weak reticulation laterally (Fig. 54); anteromedially with a semicircular cup that is raised in posterior part; propodeal callus with 10 setae. Legs yellowish-brown. Forewing: costal cell with two irregular rows of setae on ventral surface, and margin with five setae close to marginal vein; with 13 admarginal setae.

Gaster circular, dark yellowish-brown with anterolateral corners dark brown (Fig. 25).

Ratios. HE/MS/WM = 2.1/1.2/1.0; POL/OOL/POO = 8.0/4.3/1.0; OOL/DO = 1.6; WE/WF/WH/HH = 1.0/2.4/4.2/3.1; WH/WT = 1.0; PM/ST = 1.7; TS1/TS2/LT/LT1/LT2/LT3/LT4 = 4.1/2.9/6.9/2.3/1.4/1.0/1.3; LP/WP = 0.8; MM/LG = 1.3.

Variation

Several female paratypes have a dark round spot posteromedially on gaster (Fig. 26).

Male. Length of body 1.7–2.5 mm. Scape slightly enlarged, widest medially, with sensory pores along entire ventral margin. Similar to female except scutellum with ±isodiametric meshes, and gaster with posterior ½ dark brown.

Ratios. LC/WS = 2.7–2.9, LP/WP = 1.0–1.1.

Hosts

Unknown.

Distribution

France, Italy, Spain.

Etymology

From the Latin pallidus, meaning pale, referring to the predominantly pale gaster in female.

Genetic data

No specimens of the species were available for genetic analysis.

Euplectrus bicolor (Swederus)

Figures 1–2, 7–12, 48, 55

Pteromalus bicolor Swederus, 1795:204. Neotype female, designated here, in MZLU. Combined to Eulophus by Walker (1839:173), and to Euplectrus by Haliday (1844:297).

Elachertus albiventris Spinola, 1811:151. Combined to Eulophus by Haliday (1842:plate J) and to Euplectrus by Walker (1872b:112); synonymized with E. bicolor by Bouček and Askew (1968:15).

Material

Type material: Neotype female labelled “Sweden: Skåne, Kranke, Ekskogen, 55°41'10.3N, 13°27'40.2E, 5.vii.2015, C. Hansson”, ”BC-ZSM-HYM-25460-C11” in MZLU. Additional material (440♀ 306♂): Finland: 13♀ 8♂ (VV), 163♀ 125♂ (MZH, MZLU), this material includes 1♀ 1♂ from Eugraphe subrosea, 1♀ 4♂ from Agrotis sp., 4♀ 14♂ from Orthosia opima, 1♀ from Xylina sp., 4♀ 2♂ from a “polyphagous noctuid”; France: 18♀ 4♂ (NHM); Greece: 1♀ (MZLU); Hungary: 1♂ (MZLU); Norway: 1♀ 1♂ (VV); Slovenia 6♂ (MZLU), this material includes 6♂ from Orthosia sp. on raspberries (Rubus idaeus); Sweden: 179♀ 211♂ (MZLU, NHM, ZSM); United Kingdom: 65♀ 54♂ (NHM), this material includes 6♀ from Diarsia mendica, 7♀ 14♂ from Mamestra brassicae, 9♀ 26♂ from Polia hepatica, 14♀ 8♂ from Polia nebulosa. Detailed geographic information of all barcoded specimens is listed in Suppl. material S1.

Diagnosis

Frons below level of toruli with pale area not extending laterally to the eye but with a dark stripe between pale area and eye, in the female dark area is wider (Figs 9, 10) than in the male (Figs 11, 12); midline on midlobe of mesoscutum usually indicated by either a median carina (Fig. 48) or a median groove in posterior ½, in some specimens midline indicated just through a change in the reticulation; posterior part of midlobe mesoscutum narrow (Figs 48, 55), ratio width base of midlobe (a)/width base of one sidelobe (b) = 0.57±0.070 (female), 0.55±0.070 (male), width base of midlobe/width base of entire mesoscutum = 0.22±0.019 (female), 0.21±0.019 (male), n= 10 for female and male respectively.

Description (neotype)

Length of body 2.8 mm (2.0–3.1 mm in additional material). Antenna with scape yellowish-brown with dorsal edge pale brown, pedicel and flagellomeres 1+2 yellowish-brown, flagellomeres 3–6 pale brown. Mandibles and palpi yellowish-brown. Head black and shiny, lower face with median part yellowish-brown reaching laterally to level of outer edge of toruli (Figs 9, 10). Frons smooth except a reticulate band closer to anterior ocellus than to toruli, reaching from eye to eye, close to eyes with two rows of setae (Fig. 9). Vertex smooth and shiny. Occipital margin with a carina behind ocellar triangle.

Mesosoma black and shiny; midlobe with raised and strong reticulation, meshes isodiametric, midline on midlobe of mesoscutum usually indicated by either a median carina (Fig. 48) or a median groove in posterior ½, in some specimens midline indicated just through a change in the reticulation. Scutellum 0.9× as long as wide; with engraved reticulation, meshes elongate, except smooth and shiny posterior margin (Fig. 48). Dorsellum with a very narrow groove along anterior margin (Fig. 48), groove medially 0.1× as long as length of dorsellum. Propodeum smooth and shiny medially, with very weak reticulation laterally (Fig. 48); anteromedially with strongly raised triangular cup in posterior part; propodeal callus with 17 setae. Legs yellowish-brown. Forewing: costal cell with two rows of setae on ventral surface, and margin with four setae close to marginal vein; with 17 admarginal setae.

Gaster dark brown with a yellowish-brown spot in anteromedian part (Fig. 8).

Ratios. HE/MS/WM = 1.8/1.0/1.1; POL/OOL/POO = 9.7/5.3/1.0; OOL/DO = 1.5; WE/WF/WH/HH = 1.0/3.0/5.3/3.6; WH/WT = 1.0; PM/ST = 1.6; TS1/TS2/LT/LT1/LT2/LT3/LT4 = 3.6/2.3/2.3/1.3/1.0/1.8; LP/WP = 0.8; MM/LG = 0.9.

Male. Length of body 1.7–2.4 mm. Scape slightly enlarged, widest medially, with sensory pores along entire ventral margin. Similar to female except wider pale clypeal area (Figs 11, 12), wider scape, longer petiole.

Ratios. LC/WS = 3.1–3.4, LP/WP = 1.0–1.2.

Hosts

Agrotis sp., Diarsia mendica (Fabricius), Eugraphe subrosea (Stephens), Mamestra brassicae (L.), Orthosia opima (Hübner), Orthosia sp. on raspberries (Rubus idaeus), Polia hepatica (Clerck), Polia nebulosa (Hufnagel), Xylina sp., a “polyphagous noctuid”. All records are from caterpillars of the Noctuidae.

Distribution

Sweden (Swederus 1795), Finland, France, Greece, Hungary, Norway, Slovenia, United Kingdom (new/confirmed records).

Remarks

Neotype designation: the original type material for E. bicolor is lost (Graham 1963). Presumably it was originally in the Natural History Museum in Stockholm (Sweden), but cannot be found there. When Swederus described E. bicolor he was very parsimonious with information, which was as usual at that time. The description is very short and fits any European species of Euplectrus. Biological and geographical information were not included. Swederus was working in Sweden but made scientific trips to several European countries (Waldeck 2018) and it is difficult to be sure from where he had the material forming the base for the description. However, since Swederus was Swedish it is probable that he had access to Swedish material. Therefore, the neotype is selected from Swedish material, and it is selected from material belonging to the species that appears to be the most common in this country. The neotype has a DNA barcode of 621 bp and belongs to one of the two haplotypes that were found within the species (Fig. 63).

Genetic data

Genetically analysed specimens of E. bicolor exhibited comparatively high levels of intraspecific variation (maximum 6.5%) but with a distinct gap to the nearest neighbours (E. intactus, 10.9% and E. carinifer, 10.2%) (Fig. 63). The analysed specimens, all from Sweden, fall into two genetic clusters that occur sympatrically (Suppl. material S2). The absence of morphological characters to separate the two haplotypes does not preclude the possibility that E. bicolor consists of two or more species, but analysis of material of other populations and ideally additional (nuclear) gene regions will be required to clarify the status of each population.

Euplectrus flavipes (Fonscolombe)

Figures 13, 33–35, 51

Spalangia flavipes Fonscolombe, 1832:299. Lectotype female, designated by Bouček (1970:88) in OUMNH, examined. Combined to Euplectrus by Fonscolombe (1840:192).

Euplectrus cacoeciae Ferrière, 1941:42. Holotype female in NHM, examined. Synonymized with E. flavipes by Bouček (1970:88).

Material

(74♀ 39♂). Bosnia/Hercegovina: 1♀ (NHM); Cyprus: 19♀ 11♂ (NHM), this material includes 1♀ from Spodoptera litura, 6♀ 4♂ from Spodoptera exigua, 6♀ ♂ from Heliothis sp. on alfalfa (Medicago sativa), 22♀ ♂ from Plusia sp. on alfalfa; Czech Republic: 20♀ 14♂ (MZLU, ZSM), this material includes 13♀ 8♂ from Alsophila aescularia on Carpinus betulus and 2♀ and Populus alba, 1♂ from Carcina quercana on C. betulus, 1♂ from Cosmia trapezina on C. betulus, 3♀ from Cyclophora annularia on Acer campestre; France: 15♀ 9♂ (NHM, ZSM), this material includes 1♀ 2♂ from Alsophila aescularia, 1♀ from Colobochyla salicalis, 1♀ 1♂ from unknown caterpillar on Sonchus sp; Greece: 1♀ (MZLU); Hungary: 1♀ (MZLU); Italy:1♀ (NHM); Macedonia: 1♀ (NHM); Romania: 6♀ (MZLU; NHM); Serbia: 3♀ (NHM); Slovenia: 2♀ 1♂ (MZLU, NHM), this material includes 1♀ from unidentified noctuid caterpillar on tomato; Spain: 1♀ 2♂ (NHM); Switzerland: 1♀ 1♂ (MZLU), this material includes 1♀ 1♂ from Mamestra brassicae; Turkey: 2♀ 1♂ (NHM), this material includes 2♀ 1♂ from Plusia sp. Detailed geographic information of all barcoded specimens is listed in Suppl. material S1.

Diagnosis

Frons below level of toruli with pale area not extending laterally to the eye but with a wide dark stripe between pale area and eye in both sexes (Figs 33, 34); midlobe of mesoscutum with a complete median carina (Fig. 51); female with pale area in anterior ½ of first gastral tergite large and with narrow brown margins, margins about ½ as wide as width of petiole (Fig. 35); male gaster with pale part in anterior ½ reaching margin in posterior part, thus interrupting the dark lateral margins of the gaster (Fig. 13); female gaster with apex pale (Fig. 35).

Figures 27–35. 

Euplectrus spp.: 27–29 E. intactus (Walker) 27 head frontal, female 28 head frontal, male 29 gaster dorsal, female 30–32 E. maculiventris Westwood 30 head frontal, female 31 head frontal, male 32 gaster dorsal, female 33–35 E. flavipes (Fonscolombe) 33 head frontal, female 34 head frontal, male 35 gaster dorsal, female.

Hosts

Tortricidae: Archips rosana (L.) (Ferrière 1941). New/confirmed records: Depressariidae: Carcina quercana (Fabricius) on Carpinus betulus. Erebidae: Colobochyla salicalis (Denis & Schiffermüller); Geometridae: Alsophila aescularia (Denis & Schiffermüller) on C. betulus and Populus alba; Cyclophora annularia (Fabricius) on Acer campestre; Noctuidae: Cosmia trapezina (L.) on C. betulus; Heliothis sp.; Mamestra brassicae (L.); Plusia sp.; Spodoptera exigua Hübner; Spodoptera litura Fabricius, unidentified noctuid caterpillar on tomato (Solanum lycopersicum).

Distribution

Bulgaria (Ferrière 1941), France (Fonscolombe 1832), Bosnia/Hercegovina, Cyprus, Czech Republic, Greece, Hungary, Italy, Macedonia, Romania, Serbia, Slovenia, Spain, Switzerland, Turkey (new/confirmed records). This species seems to occur only in Central and South Europe, but not in northern Europe. Hedqvist (2003) listed E. flavipes from Sweden, from the province of Södermanland. One of us (CH) has seen this material in coll. Hedqvist (now in NHM), a reared series consisting of 15 females and four males and they are misidentified. Instead these specimens belong to E. bicolor.

Genetic data

Euplectrus flavipes consists of eight subclusters, each of which was assigned a different BIN by the BOLD system (Fig. 63). The subclustering coincides with a higher than usual intraspecific variation of 5.3%. Geographic subclustering in this species is prominent and four of the haplotypes have been recorded from a single country only, whereas the other haplotypes occurred in two or more countries. In Romania, three haplotypes, each with a different BIN, represented by four specimens, were recorded (Suppl. materials S1, S2). The analysed specimens do not represent the full distributional range of the species, and it is therefore to be expected that more haplotypes are present in the species. A more comprehensive sampling regime and analysis of more material and additional gene regions is required to assess the status the genetically different populations of E. flavipes.

Euplectrus intactus Walker, revised status

Figures 27–29, 49, 56

Euplectrus intactus Walker, 1872a:102. Lectotype female in NHM, examined. Synonymized with E. bicolor by Bouček & Askew, (1968: 15).

Material

(26♀ 18♂). Belgium: 3♀ 3♂ (ZSM), this material includes 3♀ 3♂ from Pieris rapae; France: 1♀ 2♂ (NHM), this material includes 2♂ from a caterpillar on Artemisia vulgaris; Hungary: 2♀ 9♂ (MZLU, NHM); Romania: 1♀ (NHM); Sweden: 7♀ 1♂ (MZLU, NHM); United Kingdom: 12♀ 5♂ (NHM), this material includes 1♀ from Noctua comes on Corylus avellana.

Diagnosis

Frons below level of toruli with pale area not extending laterally to the eye but with a wide dark stripe between pale area and eye in both sexes (Figs 27, 28); midlobe of mesoscutum usually without median groove or carina (Fig. 49, 56) (sometimes with a weak median groove at very base); posterior part of midlobe mesoscutum wide (Fig. 56), ratio width base of midlobe (a)/width base of sidelobe (b) = 0.80±0.048 (female), 0.80±0.054 (male), width base of midlobe/width base of entire mesoscutum = 0.29±0.018 (female), 0.28±0.014 (male), n=9 for female and male respectively. Very similar to E. bicolor, distinguished from this species by the wide posterior part of midlobe of mesoscutum.

Hosts

Noctuidae: Noctua comes Hübner on Corylus avellana. Pieridae: Pieris rapae (L.). From an unidentified caterpillar on Artemisia vulgaris.

Distribution

France (Corsica) (Walker 1872a), Belgium, Hungary, Romania, Sweden, United Kingdom (new/confirmed records).

Remarks

Euplectrus intactus was synonymized with E. bicolor by Bouček and Askew (1968), but DNA-data and a renewed analysis of the morphology both support that these are different species.

Genetic data

Barcoded specimens of Euplectrus intactus exhibited an intraspecific variation of 6.9% and a pronounced geographic subclustering (NJ-tree, Suppl. material S2). One of the nine different haplotypes in E. intactus was recorded from four countries (specimens with BIN BOLD:ACR7308 from Hungary and Romania, Sweden and the UK, Fig. 63). The other eight haplotypes were recorded from a single country each. More than one haplotype occurs in Sweden (four haplotypes), Belgium (two haplotypes), and Hungary (three haplotypes). As in the other Euplectrus species with high haplotype divergence, a broader sampling from different populations and geographic regions is required to clarify the status of different haplotypes of the species.

Euplectrus liparidis Ferrière

Figures 36–38

Euplectrus liparidis Ferrière, 1941:43. Holotype female in NHM, examined.

Diagnosis

Female with frons below level of toruli completely pale, pale area reaching from eye to eye (Fig. 38); midlobe of mesoscutum without median groove or carina (Fig. 37); reticulation on scutellum with elongate meshes (Fig. 37); without groove between dorsellum and scutellum (Fig. 37); female gaster with pale area in anterior part as a round spot about as wide as ½ the width of gaster (Fig. 37).

Figures 36–41. 

Euplectrus spp.: 36–38 E. liparidis Ferrière, holotype female 36 habitus lateral 37 habitus dorsal 38 head frontal 39–41 E. phthorimaeae Ferrière, holotype female 39 habitus lateral 40 habitus dorsal 41 head frontal.

Hosts

From larva of Lymantria dispar (L.) (Erebidae) (Ferrière 1941). This host is odd as the larvae are hairy, whereas larvae of all other hosts accounted for in this article are naked.

Distribution

Algeria (Ferrière 1941), Czech Republic & Italy (Zhu and Huang 2003).

Genetic data

No specimens of the species were available for genetic analysis.

Euplectrus maculiventris Westwood

Figures 14, 30–32, 50

Euplectrus maculiventris Westwood, 1832:128. Lectotype female in OUMNH, examined. Combined to Eulophus by Haliday (1842:plateJ); synonymized with E. bicolor by Bouček and Askew (1968:14); revalidated by Zhu and Huang (2002:134).

Material

(249♀ 200♂). Finland: 15♀ 8♂ (VV), 153♀ 121♂ (MZH, MZLU, ZSM), this material includes 11♀ 4♂ from Agrotis segetum, 5♀ from Eurois occulta, 4♀ from Lithomoia solidaginis; France: 22♀ 9♂ (NHM); Spain: 1♀ 2♂ (MZLU, NHM); Sweden: 35♀ 43♂ (MZLU, NHM), this material includes 6♂ from Mniotype satura; United Kingdom: 23♀ 17♂ (NHM).

Diagnosis

Female with clypeal area pale, and with pale colour drawn out towards eye and almost reaches eye but with part below the eye dark (Fig. 30), male with entire frons below level of toruli pale and with parts lateral to toruli pale (Fig. 31); female with reticulation on scutellum with isodiametric meshes (Fig. 50), reticulation usually strong but there is some variation in this and some specimens have weak reticulation; male scape 2.8–3.0× (mean 2.86, n=10) as long as wide (Fig. 14). Similar to E. bicolor, including the narrow posterior part of midlobe of mesoscutum, but can be distinguished from this species through the colour of lower face (both sexes) – pale area confined to clypeal region in E. bicolor, and through the reticulation on the scutellum (females only) – meshes elongate in E. bicolor. Males are similar to males of E. geometricida, but can be distinguished through the relatively long and slender scape.

Hosts

Agrotis segetum (Denis & Schiffermüller), Eurois occulta (L.), Lithomoia solidaginis (Hübner), Mniotype satura (Denis & Schiffermüller). All records are from caterpillars of the Noctuidae.

Distribution

United Kingdom (Westwood 1832), Finland, France, Spain, Sweden (new/confirmed records).

Genetic data

The single barcoded specimen of E. maculiventris was assigned a distinct BIN and shows a distance of 11.3% to the next neighbour species, E. bicolor (Fig. 63).

Euplectrus nigriceps Ferrière revised status

Figures 42–46

Euplectrus nigriceps Ferrière, 1941:42. Holotype female in NHM, examined. Synonymized with E. platyhypenae Howard by Bouček and Graham (1978).

Material

(1♀). Sweden: Öland, Ismantorp, 56°44'45.8N, 16°38'29.0E, 30.vi.2014, C. Hansson (MZLU).

Diagnosis

Head including clypeal area completely black (Figs 44, 45); midlobe of mesoscutum with a complete median carina (Figs 43, 46); scutellum shiny, with very weak reticulation (Figs 43, 46).

Figures 42–47. 

Euplectrus spp.: 42–46 E. nigriceps Ferrière, female 42–44 non-type specimens from Sweden 42 habitus lateral 43 thoracic dorsum 44 head frontal 45–46 holotype 45 head frontal 46 habitus dorsal 47 E. platyhypenae Howard, gaster dorsal, female specimen from Costa Rica.

Hosts

Unknown.

Distribution

Sweden (new record). This is the only geographical record for the species as the type material did not have information about collecting locality.

Remarks

Euplectrus nigriceps was described from two females and one male that stood together with British material of E. bicolor in NHM, but all three specimens lacked locality information (Ferrière 1941). In spite of this lack of information E. nigriceps was regarded as European by Ferrière. Graham (1963) included E. nigriceps in an addition to the British species of the Eulophidae, but because of the lack of information on the type specimens he expressed doubts about the record. Later Bouček and Graham (1978) synonymised E. nigriceps with E. platyhypenae, a species found in the Nearctic and Neotropical regions (Hansson et al. 2015). These two species are very similar, e.g. through the completely dark head, complete median carina on midlobe of mesoscutum, and the shiny scutellum with very weak reticulation. But they also differ. The female gaster is different: in E. platyhypenae the gaster is pale with narrow dark lateral margins (Fig. 47), but in E. nigriceps it is dark brown in posterior ½, in anterior ½ pale with wide dark lateral margins (Fig. 46).

Genetic data

The single genetically examined specimen of E. nigriceps (BC-ZSM-HYM-29751-A01) has a distance of 11.4% to the next neighbour species, E. bicolor.

Euplectrus phthorimaeae Ferrière

Figures 39–41

Euplectrus phthorimaeae Ferrière, 1941:42–43. Holotype female in NHM, examined.

Diagnosis

Female with frons below level of toruli with pale area not extending laterally to the eye but with a wide dark stripe between pale area and eye (Fig. 41); midline on midlobe of mesoscutum indicated by a median groove in posterior ½ (Fig. 40); posterior part of midlobe of mesoscutum narrow as in E. bicolor; scutellum with isodiametric meshes in posterior part (Fig. 40).

Hosts

Phthorimaea operculella (Zeller) (Gelechiidae) (Ferrière 1941).

Distribution

Cyprus & Israel (Ferrière 1941).

Genetic data

No specimens of the species were available for genetic analysis.

Figures 48–51. 

Euplectrus spp., mesosoma dorsal, female: 48 E. bicolor (Swederus) 49 E. intactus (Walker) 50 E. maculiventris Westwood 51 E. flavipes (Fonscolombe).

Figures 52–56. 

Euplectrus spp. 52–54 mesosoma dorsal, female 52 E. geometricida sp. n. 53 E. carinifer sp. n. 54 E. pallidigaster sp. n. 55–56 mesoscutum, female, a = width of base of midlobe, b = width of base of sidelobe 55 E. bicolor (Swederus) 56 E. intactus (Walker).

Figures 57–62. 

Platyplectrus spp., females: 57–58 mesoscutum and scutellum, dorsal 57 P. laeviscuta (Thomson) 58 P. pannonica Erdös 59–60 vertex 59 P. pannonica 60 P. chlorocephala (Nees) 61–62 head including antenna, lateral 61 P. bouceki (Erdös) 62 P. laeviscuta.

Figure 63. 

Neighbour-joining tree of Euplectrus, with colours indicating different Barcode Index Numbers (BINs). For a fully resolved tree with additional terminal taxa information, including sequence length and country of origin, see Suppl. material S2.

Discussion

Analysis of molecular and morphological data

Euplectrus is a cosmopolitan group currently including 203 species and because of the interspecific morphological similarity the species are easily recognizable as belonging to Euplectrus. Members of Euplectrus thus seem to be very conservative regarding the evolution of morphological features. This similarity between species frequently causes problems when specimens are identified using morphological features. And yet the intra- and interspecific variation of DNA barcode sequences are, compared to most other groups of insects, very large – at least among some of the European species treated here. Consider for instance E. bicolor and E. intactus, two morphologically very similar species, almost identical, that prior to this article were regarded as one species. They can be separated by just one morphological character and yet the minimum genetic distance between them using data from CO1 is 10.9%, which compared to species from other insect groups is a very large gap. Both species also exhibit large intraspecific variation in CO1, 6.5% in E. bicolor (including two sympatric subclusters) and 6.9% in E. intactus (including nine subclusters, each with a different BIN). The large intraspecific variations of the COI barcode fragment, also present in some other species treated here, may indicate the presence of more species in the material included. However, pending more sampling from different populations and geographical regions, and further analyses using more gene regions, we prefer to regard as species only those that show consistent morphological differences, no matter how small these differences may be. Considering the high intraspecific variation within most species and the virtual absence of diagnostic characters it seems mandatory for accurate identification of Euplectrus to provide DNA barcodes with each identification at species level.

Hosts

The hosts presented in this article (Table 1) are all from information given on pins of the Euplectrus specimens examined. This is a potential source of error as we cannot verify the identity of these host names. Nevertheless, we accept these as they are presented, with the nomenclature updated. Using this, probably very incomplete information on host range for each species, following can be speculated upon.

Host records for examined specimens of Euplectrus (host records in the literature are not included due to uncertainty regarding previous identifications of Euplectrus species).

Host Euplectrus species
Depressariidae:
Carcina quercana (Fabricius) E. carinifer, E. flavipes
Erebidae:
Colobochyla salicalis (D. & S.) E. flavipes
Lymantria dispar (L.) E. liparidis
Gelechiidae:
Phthorimaea operculella (Zeller) E. phthorimaeae
Geometridae:
Agriopis aurantiaria (Hübner) E. geometricida
Agriopis marginaria (Fabricius) E. geometricida
Alcis repandata (L.) E. geometricida
Alsophila aescularia (D. & S.) E. flavipes, E. geometricida
Angerona prunaria (L.) E. geometricida
Cyclophora annularia (Fabricius) E. flavipes
Colotois pennaria (L.) E. geometricida
Epirrita dilutata (D. & S.) E. geometricida
Macaria brunneata (Thunberg) E. geometricida
Operophtera brumata (L.) E. geometricida
Phigalia pilusaria (D. & S.) E. geometricida
Noctuidae:
Agrotis segetum (D. & S.) E. geometricida, E. maculiventris
Agrotis sp. E. bicolor
Amphipyra pyramidea (L.) E. carinifer
Anarta myrtilli (L.) E. geometricida
Autographa gamma (L.) E. carinifer
Cosmia trapezina (L.) E. flavipes
Diarsia mendica (Fabr.) E. bicolor
Eugraphe subrosea (Stephens) E. bicolor
Eurois occulta (L.) E. maculiventris
Heliothis sp. on Medicago sativa E. flavipes
Lithomoia solidaginis (Hübner) E. maculiventris
Mamestra brassicae (L.) E. bicolor, E. flavipes
Mniotype satura (D. & S.) E. maculiventris
Noctua comes Hübner E. intactus
Orthosia cruda (D. & S.) E. carinifer
Orthosia opima (Hübner) E. bicolor, E. geometricida
Orthosia sp. E. bicolor
Perigrapha munda (D. & S.) E. carinifer
Plusia sp. on Medicago sativa E. flavipes
Polia hepatica (Clerck) E. bicolor
Polia nebulosa (Hüfnagel) E. bicolor
Spodoptera exigua Hübner E. flavipes
Spodoptera litura Fabricius E. flavipes
Xylina sp. E. bicolor
Pieridae:
Pieris rapae (L.) E. intactus
Tortricidae:
Archips rosana (L.) E. flavipes

The host range for European Euplectrus species where we have been able to examine a larger material (Table 1) seems to be extensive, and hosts from either Noctuidae or Geometridae are the dominant target groups. Apart from having wide host spectra, species can also overlap in their host preferences. Sometimes two Euplectrus species have been recorded from the same host species. Euplectrus geometricida seems to favour geometrids and share this host group with E. flavipes. Both species also parasitize noctuids, which is also the target group for E. bicolor and E. maculiventris. Euplectrus flavipes, a species that probably only occurs in Central and South Europe, has been recorded from four Lepidoptera families, including geometrids and noctuids. This wide host spectrum and host overlap in European Euplectrus species is in stark contrast to the situation in some tropical areas, as presented by Hansson et al. (2015). Analysing the Euplectrus fauna in the Área de Conservación Guanacaste, a comparatively small area (1470 km2) in north-western Costa Rica, they recognized 75 Euplectrus species, diagnosed through data from both the morphology of the adult wasps and from CO1, i.e. the same set of characters we have used for European species in this article. The species were either (usually) host-specific to a particular species of caterpillar or (occasionally) to a particular life-form of caterpillar within a genus or family, and those usually feeding on a narrow range of food plants. Host overlap between species were rare, occasionally two Euplectrus species parasitized the same host species. The differences between tropical and temperate patterns of diversity in Euplectrus are in conformity with other groups of parasitic wasps (e.g. Fernandez-Triana et al. 2014, Smith et al. 2008). The results found here for European species compared to the results for tropical species accounted for in Hansson et al. (2015) suggest that a more refined niche separation in tropical areas is at least part of the explanation for the much higher species diversity in such areas.

The host larvae presented here are with one exception naked. The exception is Lymantria dispar, the only known host for E. liparidis, which has distinctly hairy caterpillars in all stages. The presence of hairs presents a mechanical obstacle, and the lack of such hairs is possibly a prerequisite for the female wasp to walk about on the host and enabling her to anchor her eggs in the cuticle of the host. Either the record for E. liparidis is a mistake, or females of this species use a different approach when laying eggs on the host. Apart from the host name very little is known about the biology for this species.

Acknowledgements

Loan of material: Natalie Dale-Skey (NHM), James Hogan (OUMNH), Martti Koponen (MZH), Juho Paukkunen (MZH), Hege Vårdal (NHRS), Veli Vikberg (Turenki, Finland), staff from the Swedish malaise trap project (SMTP). Špela Modic (Ljubljana, Slovenia) for photos of parasitized caterpillars. Reared material was provided by Martin Šigut, Pavel Drozd, Mark Shaw, and Martin Volf. Ola Gustavsson (SEM, Lund University). The project was funded by the Swedish Taxonomy Initiative (dha 2013-202), and by the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, Germany, German Barcode of Life project). The sequence analyses for this study were supported, in part, by Genome Canada through the Ontario Genomics Institute, while informatics support was provided through a grant from the Ontario Ministry of Research and Innovation.

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