Research Article |
Corresponding author: H. Charles J. Godfray ( charles.godfray@biology.ox.ac.uk ) Academic editor: Jovana M. Jasso-Martínez
© 2024 H. Charles J. Godfray, Cornelis van Achterberg.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Godfray HCJ, van Achterberg C (2024) A new European species of Mesocrina (Hymenoptera, Braconidae, Alysiinae, Alysiini) with notes on the biology and systematics of the genus. Journal of Hymenoptera Research 97: 349-361. https://doi.org/10.3897/jhr.97.124215
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Mesocrina chandleri Godfray & van Achterberg, sp. nov., is described in the small Holarctic genus Mesocrina Foerster, 1863, the second European species. The holotype was collected in England and further specimens are recorded from Finland, France and the Netherlands. A key is provided to the Palaearctic Mesocrina species. DNA sequence from the CO1 barcode locus was obtained and the new species is 10% divergent from M. indagatrix (the other European species) and 5% divergent from an undetermined North American species. We provide evidence that Mesocrina spp. parasitise cyclorrhaphan Diptera in fungi (and that previous host records from phytophagous insects are incorrect) and that the taxon is not part of the Dapsilarthra genus-group as often previously assumed.
DNA barcode, Europe, hosts, Mesocrina chandleri, Palaearctic key
The genus Mesocrina Foerster, 1863 was erected for M. indagatrix Foerster, 1863, which for a long time was the sole member of the genus as understood today. In the last quarter of the 20th century four further species were described from the Eastern Palaearctic and India (
Mesocrina indagatrix, hitherto the only species known from Europe (
Details of the holotype and five paratypes are given below in the type designation. The holotype is deposited in the National Museum of Scotland, Edinburgh, the male paratype in the Zoological Collections of the Finnish Museum of Natural History, University of Helsinki, Finland, and the remaining paratypes in the entomological collection of the Naturalis Biodiversity Center, Leiden.
The specimen of Mesocrina indagatrix from which DNA sequence was obtained has the data: ♀, Savernake Forest, Wiltshire, England, United Kingdom (51.402N, 1.694E; UK Grid Reference SU214671); Malaise trap, 22 August – 25 September 1991; (collector not recorded); (Sample ID: NR1040; BOLD process ID: BRAAL476-19).
Photographs were taken through a Leica M125C microscope with focus stacking using the Leica Application Suite X (LAS X) image analysis software with final processing in Photoshop. Ratio measurements were also made using the LAS X system. Morphology terminology follows
CO1 sequencing was carried out by the Biodiversity Institute of Ontario at the University of Guelph with initial Sanger sequencing supplemented in the case of the M. indagatrix specimen by “next generation” short read sequencing (
Holotype , ♀, south side of Haugh Wood, Herefordshire, England, United Kingdom (52.021°N, 2.600°W; UK Grid Reference SO589360); 10 October 1998; swept, P.J. Chandler; National Museum of Scotland (Sample ID: NR980; BOLD process ID: BRAAL477-19).
Paratype , ♂, near Nurmijärvi, Uusimaa, Finland (60.523°N, 24.842°E; Finnish Grid Reference 6711:381); 8 September 1994; Malaise Trap, M. Koponen; Finnish Museum of Natural History (MZH) (Sample ID, MZH_GQ.22; BOLD process ID: LEFIJ28469-22).
Paratype , ♀, Lac de Remoray, Doubs, France (46.785°N, 6.254°E; French [Lambert 93] Grid reference 948242, 6634560); 27 October 2021; Malaise Trap, H. Gens, (RMNH’23”) Naturalis Biodiversity Center.
Paratypes 2 ♀, Veluvia-Hamelakkers, Wageningen, Gelderland, The Netherlands (51.969°N, 5.681°E); 25–29th October 2022; caught at a skylight, D. Belgers, RMNH’23”; Naturalis Biodiversity Center.
Paratype , ♀, Wassenaar, Zuid-Holland, The Netherlands (52.142°N, 4.379°E; Dutch [RDS] Grid reference 86.60, 462.12); 20 October 2023; on underside of Armillaria mellea (honey fungus), P.H. Hoekstra, RMNH’23”; Naturalis Biodiversity Center.
The new species is named for Peter J. Chandler, the eminent Diptera entomologist who collected the first specimen in 1998.
Holotype
, ♀, length of body 3.8 mm, of fore wing 4.7 mm (Fig.
Head. Antenna with 36 segments, 1.1 times length of fore wing and 1.5 times body, densely clothed with anteriorly directed setae projecting at an angle of 30°; length of third segment 0.7 times fourth segment, lengths of third, fourth and penultimate segments 3.9, 2.7 and 2.4 times their widths, respectively; maxillary and labial palps with 6 and 4 segments, respectively; length of maxillary palp ~ 2.6 times height of eye; OOL 2.3 times greater than POL, POL 1.4 times posterior ocellus diameter; in dorsal view head 2.0 times wider than maximum length, margin of temples posterior to eye slightly convex; vertex shiny with scattered anteriorly-directed setae especially near occiput and margin of eye, a weak furrow runs from between posterior ocelli to occiput; frons largely smooth and glabrous with small areas of rugosity and a small number of setae; dorsal length of eyes 0.6 times maximum length of head, glabrous; face 1.8 times wider than high medially, 0.6 times as wide as head, largely smooth with some slight rugosity medially, with moderately dense setae apart from a narrow medial glabrous band, the setae dorsally directed except at sides where they point laterally and latero-ventrally; clypeus glabrous with sparse punctures, ventral margin very slightly convex, epistomal suture distinct; malar space 0.15 times basal width of mandible; mandibles 1.6 times longer than maximum width which is 1.3 times basal width, finely rugulose and setose; three teeth with the central pointed and 0.3 times mandible length, the others obtuse and slightly reflexed relative to the axis of the mandible, no sharp incisions between teeth; head 1.3 times as wide as mesoscutum.
Mesosoma. Length of mesosoma 1.25 times its height; pronope absent; side of pronotum glabrous and largely smooth with some crenulation antero-medially and ventrally; mesopleuron smooth with scattered setae, mesopleural sulcus finely crenulate, precoxal sulcus completely absent; mesosternum with moderately dense posteriorly directed setae and a narrow punctate sulcus; metapleuron shallowly rugulose with sparse setae; mesoscutum with a triangular area of dense setae and punctation on its anterior surface extending somewhat dorso-medially, but dorsal surface largely shiny with sparse setae, notauli punctate anteriorly but absent from dorsal surface, a medio-posterior groove runs from 2/3 to posterior edge, margin adjoining pronotum with longitudinal striae; scutellar sulcus 3.0 times as wide as long, with a strong medial carinae and two pairs of weaker lateral carinae; scutellum smooth with a few setae; axillar depression well developed and weakly crenulate; metanotum rugose with an indistinct antero-medial carina that bifurcates posteriorly, not protruding in lateral view; propodeum rugulose anteriorly, medially and laterally, with a relatively smooth area latero-medially, posterior region adjacent to insertion of first metasomal tergite incised and raised with horizontal striae, lateral posterior margin with small protuberance, surface with scattered sparse setae.
Wings. Fore wing: closed marginal, three submarginal, discal and subdiscal cells; pterostigma sub-elliptical, about 4.5 times as long as maximally wide, r inserted at about 0.4 times the length of the pterostigma, anterior ventral margin of pterostigma before insertion convex, beyond insertion it narrows and merges gradually with 1-R1; length of r 0.6 times the width of pterostigma, approximately orthogonal to anterior wing margin; ratio of r: 3-SR: SR1 = 1: 5.2: 9.3, SR1 slightly sinuate ending near wing apex; second submarginal cell narrows distally, 5-sided (i.e. m-cu postfurcal), ratio 2-SR: 3-SR: r-m: 2-M = 1: 1.45: 0.46: 2.16, angle subtended by 2-SR and 3-SR 125°, 2-SR slightly sinuate; 1-CU1 very short; 3-CU1a 1.3 times longer than CU1b; CU1a concave down and extends nearly to wing margin. Hind wing: closed basal cell; cu-a and 2-M present.
Legs. Hind coxa smooth; hind femur ~ 5 times longer than maximally wide, densely clothed with short setae dorsally projecting at an angle of 30°, ventrally approximately half the width of the femur and projecting at 60°; hind tibia slender, densely clothed with setae (projecting at 30°), 1.15 times longer than tarsi; apical tibial spur inconspicuous, less than 0.2 times length of basitarsus; tarsi with similar setae to tibia, tarsal segment length ratios 1 (basitarsus): 0.53: 0.42: 0.31: 0.38; tarsal claws and arolium well developed and 0.75 times length of fifth tarsal segment; structure of fore and mid legs similar though femur more slender and legs shorter, ratio of hind: mid: fore femur 1: 0.90: 0.81.
Metasoma. Length of first tergite 1.7 times its apical width, the latter 1.7 times its narrowest width near its base, a pair of dorsal carinae arise basally from the lateral carinae and reach the dorsum at about ¼ and run close together in parallel to about ½ where they lose their distinctiveness, posterior dorsal surface with longitudinal sculpturing and sparsely scattered setae, a distinct dorsope present; metasoma beyond first tergite strongly lateral compressed with a strong dorsal medial carina extending from the third tergite to the end; second tergite smooth; scattered setae on second and posterior tergites; ovipositor straight and projecting, its exposed setose part 0.7 times the length of the hind tibia; ovipositor sheath with posterior directed setae projecting at an angle of 60–80°, their length up to twice the width of sheath; hypopygium slightly postero-ventrally produced, terminating at level of the cerci.
Colour. Head, mesosoma and metasoma dark brown except for yellow brown parts: scape, pedicel, base of the third antennal segment, mandibles (apart from tooth tips) and ventral part of gena, latero-ventral prothorax, tegulum, medio-ventral region of the laterally-compressed metasoma; precoxal area of mesopleuron slightly lighter than the remainder of the surface; palps and legs yellow, the mid and hind tarsi slightly darker, areola contrastingly dark brown; wing venation and pterostigma dark brown, wing membrane hyaline.
The French and Netherland female specimens generally match the holotype. The number of antennal segments were 34 and 37 (two specimens without complete antenna); extent of setation on dorsal surface of mesoscutum varies from comparatively well developed as shown in holotype (Fig.
Paratype
, ♂, length of body 3.3 mm, of fore wing 4.1 mm (Fig.
This specimen is somewhat damaged with both antennae truncated and some legs missing. Similar to the female but differing in the following features.
Head. Posterior ocelli slightly closer together (OOL 3.4 times POL); face somewhat less setose.
Wings. Veins thicker than in female; second submarginal cell slightly shorter – ratio of r: 3-SR: SR1 = 1: 4.3: 8.3, ratio 2-SR: 3-SR: r-m: 2-M = 1: 1.37: 0.38: 2.06.
Legs. Hind leg first tarsal segment slightly longer – tarsal segment length ratios = 1 (basitarsus): 0.50: 0.36: 0.26: 0.34.
Mesosoma. Anterior surface of mesonotum setose but setae extending less onto the dorsal surface than in the female holotype; propodeum smoother.
Metasoma. The metasoma is not laterally compressed and does not have longitudinal carinae on the posterior tergites; thus, having a “normal” Alysiini appearance.
Colour. Ventral margin of clypeus yellow; metasoma more uniformly brown.
Sequence data from the mitochondrial CO1 gene (the standard barcode locus) were obtained from the M. chandleri holotype (607 base pairs) and a British specimen of M. indagatrix (550 b.p.). A male Finnish specimen with identical gene sequence to the holotype was found in the BOLD database. No further Old World sequences were present in BOLD, but it did contain seven closely-related North American sequences, some identified as Mesocrina and others that appeared from images in BOLD to belong to the genus. A maximum likelihood phylogenetic tree (CO1 gene, Tamura-Nei model; default MEGA settings) of the 10 sequences was created (Fig.
Maximum-likelihood tree (CO1 gene, Tamura-Nei model) with branch lengths of the 10 Mesocrina sequences in the BOLD database. The height of the terminal triangular wedges represents sample number and their horizontal width the genetic variation within the species (where no variation the wedge is a vertical line). Letters represent putative and undetermined Canadian (A, B, D) or Californian (C) species of Mesocrina.
Mesocrina chandleri (BIN: BOLD:ADX0117) shows a 6.5% divergence from its nearest relative, a Californian BIN (BOLD: AFO2946) represented by a single specimen. The two together with a Canadian BIN (3 specimens, BOLD:ACD3275) form a clade separated by 6.1% from a clade containing M. indagatrix (BOLD:AED2809) and two Canadian BINs (BOLD:AAU8494 & ACL6319). M. indagatrix shows a 11.6% separation from M. chandleri and 6.0% from the nearest Canadian BIN. The genetic data thus strongly supports the distinctiveness of the new species.
The Palaearctic species of Mesocrina Foerster can be distinguished by the following key which is based on
1 | Precoxal sulcus distinctly crenulate; posterior surface of propodeum sloping vertically; first metasomal tergite about as long as its apical width; mesoscutum, pronotum and mesosternum brownish yellow; propleuron brownish; [vein r of fore wing much longer than wide; vein 1-SR short]; India, N. China (Jilin, Fujian, Hainan, Yunnan) | M. dalhousiensis Sharma, 1978 |
– | Precoxal sulcus smooth or absent; propodeum gradually sloping posteriorly; first metasomal tergite 1.2–2.0 times as long as its apical width; at most the pronotum ventrally, and the propleuron, brownish yellow | 2 |
2 | Setose part of ovipositor sheath about as long as first tergite, 0.3–0.5 times as long as hind tibia (and shorter than apical height of metasoma and 0.13–0.14 times as long as fore wing); anterior half of middle lobe of mesoscutum largely glabrous and without distinct punctures; Palaearctic & NE Oriental; Fig. |
M. indagatrix Foerster, 1863 |
– | Setose part of ovipositor sheath 1.5–2.0 times as long as first tergite, 0.7–0.9 times as long as hind tibia (and about equal to apical height of metasoma and about 0.2 times as long as fore wing); anterior half of middle lobe of mesoscutum more or less setose and with some punctures | 3 |
3 | Third antennal segment about 1.2 times longer than fourth segment; third tooth of mandible much smaller than first tooth; pterostigma robust and strongly sclerotised, about 5.0 times wider than length of vein r; [clypeus blackish]; East Palaearctic | M. lesovik Belokobylskij, 1998 |
– | Third antennal segment 1.5–1.7 times longer than fourth segment; third tooth of mandible similar to first tooth or larger; pterostigma more slender and less sclerotised, about twice times wider than length of vein r | 4 |
4 | Mandible less robust, with first tooth of mandible not protruding and similar to third tooth; vein 2-SR of fore wing distinctly sinuate; antenna with 31–32 segments; propodeum without sculpture medially; East Palaearctic | M. licho Belokobylskij, 1998 |
– | Mandible more robust, with first tooth of mandible rather protruding and sometimes larger than third tooth; vein 2-SR of fore wing straight or slightly sinuate; antenna with 34–40 segments; propodeum more rugulose or with carina medially | 5 |
5 | Vein r of fore wing 0.8 times maximum width of pterostigma and narrow; first metasomal tergite 1.1 times as long as apically wide, twice as wide posteriorly as minimum width; propodeum with distinctly developed medio-longitudinal carina; clypeus largely yellow; second submarginal cell of fore wing robust and vein SR1 about 2.2 times as long as vein 3-SR; [middle lobe of mesoscutum only anteriorly setose (confined to anterior edge)]; East Palaearctic. | M. leshii Belokobylskij, 1998 |
– | Vein r of fore wing thickened and 0.3–0.6 times maximum width of pterostigma; first metasomal tergite 1.7 times as long as apically wide, 1.7 times as wide posteriorly as minimum width; propodeum at most with weakly developed medio-longitudinal carina; clypeus dark brown or yellowish near ventral rim; second submarginal cell of fore wing less robust and vein SR1 1.7–2.0 times as long as vein 3-SR; [linear medio-posterior depression deep and comparatively long; females with 34–37 antennal segments; setose area of middle lobe of mesoscutum variable]; West Palaearctic; Figs |
M. chandleri sp. nov. |
In Europe only M. indagatrix (Fig.
Females of both European species of Mesocrina and an American species (
The UK, Netherland and French specimens of the new species were all captured in October while the more northerly record from Finland is from September. The three specimens of M. indagatrix in the NMS collection were also collected in the autumn. The abundance of fungal fruiting bodies peaks at this time of year, and so the phenology and putative biology are consistent. Mesocrina chandleri is a relatively large and distinctive species (for an Alysiini) and given how widespread it is we are surprised it has not been noted before, especially as some of the recent records come from sites that have been regularly surveyed for Braconidae. We speculate that the species may be undergoing a current expansion of range and/or abundance.
There are currently eight described species of Mesocrina, six from the Palaearctic and two from the Nearctic (
The genus Mesocrina was described by
We are grateful to Sergey Belokobylskij for supplying photographs of the holotype of Mesocrina leshii, to Mark Shaw for access to the National Museum of Scotland’s collection, to Marko Mutanen and Juho Paukkunen for loan of the male paratype, and to Paul Hebert & Jayme Sones (University of Guelph) for DNA sequencing and information from the BOLD database.