Research Article |
Corresponding author: Jaakko Pohjoismäki ( jaakko.pohjoismaki@uef.fi ) Academic editor: Pierfilippo Cerretti
© 2021 Jaakko Pohjoismäki, Christer Bergström.
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:
Pohjoismäki J, Bergström C (2021) Review of the Nordic Gymnocheta Robineau-Desvoidy (Diptera, Tachinidae) with report of two species new to Europe. ZooKeys 1053: 145-184. https://doi.org/10.3897/zookeys.1053.52761
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The genus Gymnocheta Robineau-Desvoidy, 1830 (Diptera, Tachinidae) has until now been represented by two species in Europe, G. viridis (Fallén, 1810) and G. magna Zimin, 1958. Two species are newly recorded from Finland and Sweden, Gymnocheta lucida Zimin, 1958 and G. zhelochovtsevi Zimin, 1958, both previously known only from the Russian Far East and Japan. These four European species are redescribed and illustrated, including the first description of the female of G. zhelochovtsevi. A key is provided to seven of the eight described species of Palaearctic Gymnocheta. The holotype of G. viridis was examined and found to differ from the present concept of the species, instead matching the concept of the more recently described G. magna. In the interests of nomenclatural stability, the two names are maintained in their current usage pending a request to the International Commission on Zoological Nomenclature to replace the current holotype of G. viridis with a neotype that corresponds to the long-established concept of that species.
DNA barcoding, Co1, Ernestiini, Fennoscandia, Gymnocheta, new species, species diversity, synonymy, Tachininae, type specimens
The genus Gymnocheta Robineau-Desvoidy, 1830 constitutes a morphologically homogenous group within the large and multiform tribe Ernestiini and includes medium to large (5.0–13.0 mm), semi-robust tachinids, easily recognisable by their metallic green colouration (Fig.
Gymnocheta spp. habitus A habitus Gymnocheta viridis ♂ B–E Tachina viridis Fallén, holotype specimen B dorsal view C head in lateral view. Note the protruding lower facial margin (arrowhead) D detail of the right wing edge. Note the reduced costal spine (arrowhead) E sternite 5 of the holotype F labels associated with the holotype. All photographs by Göran Liljeberg.
Gymnocheta is currently known from eight species in the Palaearctic Region (
During a DNA barcoding study of Finnish Tachinidae (
A survey of the potential species candidates for the two unknown Nordic species among the described Palaearctic species found tentative matches with the descriptions of G. lucida and G. zhelochovtsevi. The species identities were later confirmed by comparing Nordic specimens with Russian and Japanese material. As an aid to future researchers, redescriptions of both species (originally described in Russian), including also the previously unknown female of G. zhelochovtsevi, are provided and full redescriptions of the other European species are given. Also included are notes on the known biology of the species and a key for the identification of the Palaearctic Gymnocheta species (not including the little-known G. goniata).
An examination of the holotype of Tachina viridis Fallén, 1810 (Fig.
Male and female terminalia were dissected and prepared for examination following the method described by
AHC Private collection of A. Haarto, Mietoinen, Finland;
CBC Private collection of C. Bergström, Uppsala, Sweden;
JPC Private collection of J. Pohjoismäki, Joensuu, Finland;
REC Private collection of Roger Engelmark, Gubböle, Sweden;
TMNH Tampere Museum of Natural History, Tampere, Finland;
Label data are given verbatim using the following symbols: / for the end of a line and beginning of the next; // at the end of a label and beginning of the next (from top to bottom on the same pin).
The classification follows
Cytochrome oxidase subunit 1 (Co1) DNA barcoding was performed as a part of the Tachinidae project of Finnish Barcode of Life initiative (FinBoL). The 5´-terminal part of Co1 was amplified using the routine barcoding primers LepF1 and LepR1 (
Sequence comparisons were performed using MUSCLE alignment (
For clarity, the information for the material on Gymnocheta lucida, G. magna, G. viridis, and G. zhelochovtsevi is given under the corresponding species descriptions. In addition to these species, the following non-European species is also included to confirm the identity of the Nordic G. zhelochovtsevi.
Gymnocheta porphyrophora Zimin, 1958
China: (1♂, 1♀) 1♂: Сев. предгорье......., Грум-Гржимайло, 14.V.1890 [Northern Foothills....... (not readable), Grum-Grzhimailo, 14.V.1890]; 1♀: р. Сэрг-чу, 13800, близ Желтей, Тибет, Козлов, конец V.1901 [river Sarg-chu, 13800, near Yeltei, Tibet, Kozlov, end V.1901]. Coll. A. Semenov-Tian-Shansky. [
Fifth sternites of Gymnocheta spp. males A Gymnocheta lucida male abdomen. Note the narrow profile of the posterior edge of the fifth sternite (arrow) B the edge of the fifth sternite in G. viridis is bulky and protruding beyond the tip of the abdomen, clearly recognisable from the side C the posterolateral lobe of G. zhelochovtsevi is somewhat subrectangular as in G. magna, but more rounded in profile. Note the apical hook of the syncercus D in contrast to G. zhelochovtsevi, posterior edge of fifth sternite in G. porphyrophora with well-developed median lobes (arrow) E dissected fifth sternites of Nordic Gymnocheta spp. in comparison: i) G. lucida, ii) G. magna, iii) G. viridis and iv) G. zhelochovtsevi. A distinct dorsomedial process present in G. magna and G. viridis Abbreviations: bpl–basal plate; dmp–dorsomedial process; mcl–median cleft; pll–posterolateral lobe; tms–transversal median stripe; wll–wart-like lobe (or median lobe). Photograph D by V. Neimorovets, rest by J. Pohjoismäki.
Gymnocheta
Robineau-Desvoidy, 1830: 371 (also subsequently spelled Gymnochaeta, unjustified emendation). Type species: Tachina viridis Fallén, 1810 (as viridis Meigen), by monotypy (see also
(European species). Male (Figs
Colouration (Fig.
Thorax and abdomen with different shades of metallic green but often also partly blue, purple or red. In our European species G. magna and G. viridis show a bright metallic ground colour, G. lucida an olive green and G. zhelochovtsevi a dark green colour, the shine depending on the direction of the light. Scutum, when viewed from the side and slightly from behind, with four black longitudinal stripes of microtomentum, changing from grey to purple depending on the direction of the incident light; presutural area with the medial stripes narrow and widely separated, the lateral stripes are wedge-shaped and reach the level of posthumeral seta. In aged specimens, caught late in the season, the microtomentum can be worn off and give the specimens a polished appearance on scutum. Proepisternum black and densely covered with microtomentum or with the metallic green colour slightly subshiny. Legs normally extensively black or dark brown, which can change to lighter brown in aged specimens; fore coxa in anterodorsal region and sometimes also femora with remnants of metallic green or blue tint, covered with light grey microtomentum. Wing veins black and/or brownish black, wing membrane with a brownish tinge. Wing membrane around crossvein r-m sometimes narrowly infuscate. Tegula and basicosta dark brown to black. Halteres brown but stalk and knob partly blackish. Calypters greyish white, edge for the most part beige but inner edge distinctly infuscate, with a white fringe.
Head (Figs
Thorax (Fig.
Legs (Fig.
Wing (Fig.
Abdomen (Figs
Male terminalia (Figs
Aedeagus: Basiphallus with a basal projection and a distinct digitiform epiphallus. Distiphallus in lateral view (Fig.
Comparison of Gymnocheta spp. male terminalia A lateral view of the terminalia: i G. lucida ii G. magna iii G. viridis and iv G. zhelochovtsevi – note the apical hook of the syncercus B dorsal view of the terminalia: i G. lucida ii G. magna iii G. viridis and iv G. zhelochovtsevi, same specimen as in Fig.
Female (Figs
Colouration : Fronto-orbital plate with a more widespread metallic green colour; the metallic ground colour continues down on the upper part of parafacial; in large parts covered by greyish microtomentum in G. zhelochovtsevi.
Head (Fig.
Legs : Legs black. Claws and pulvilli on fore legs shorter ca. 0.7–0.8 × as long as tarsal segment 5, the latter 1.5–1.7 × longer than tarsal segment 4.
Abdomen : Tergite 5 trapezoid, along anterior margin ca. 2 × as wide as long.
Female terminalia (Fig.
Comparison of Gymnocheta spp. female sternites and terminalia A ventral view of the sternites and terminalia of i G. lucida ii G. magna iii G. viridis and iv G. zhelochovtsevi B detail of the female terminalia of i G. lucida ii G. magna iii G. viridis and iv G. zhelochovtsevi. Note the long cerci in G. zhelochovtsevi. All photographs by J. Pohjoismäki.
Tergite 6 reduced into narrow and somewhat elongated hemitergites, widely separated, in the membranous region accompanied by 0–3 tiny setulae posterior to the seventh spiracle and sometimes also one or two setulae in a more apical position, sixth spiracle in lateral margin of tergite 6. Sternite 6 shorter 0.5–0.7 × as long as, but slightly wider (1.1–1.2 ×) than sternite 5, 1.5–2 × as wide as long with 4–8 strong setae along the posterior margin accompanied by numerous setulae in posterior 1/5. Tergite 7 strongly reduced, divided into two widely separated small hemitergites located close to the lingulae, with 0–3 setulae in the adjacent membranous area, left and right seventh spiracles displaced in membrane between tergites 6 and 7, sometimes close to sixth spiracles. Sternite 7 ca. as long but slightly narrower than sternite 6, with numerous tiny setulae most of them restricted to the posterior margin, anterior 4/5 bare. Tergite 8 missing (fully reduced). Sternite 8 strongly reduced, hidden between hypoproct and sternite 7; covered by sensory pores (sensilla trichodea). Hypoproct in ventral view semi-circular to almost triangular, with a middorsal depression, densely covered with setulae, in lateral view (Fig.
The European species of Gymnocheta are treated in alphabetical order. All Finnish records are stored in the Finnish species database, www.laji.fi.
Gymnocheta lucida
Zimin, 1958: 60. Lectotype ♂ [
Russia: Lectotype ♂, by designation of
Gymnocheta lucida Zimin is a dark metallic olive to bronze-green tachinid, often with a matt appearance due to a dense microtomentum, which also gives the genal dilation a greyish white appearance.
Body length: 7.2–9.5 mm (n = 29).
Male (Figs
Colouration : Head covered with dense greyish white microtomentum. The metallic ground colour of the genal dilation shines through weakly, compared to G. magna and G. viridis. However, this difference is sometimes hard to recognise, as the interpretation depends on the direction of the incidence of light, and the specimens should be viewed from different angles. Facial plate black normally without a metallic green spot. Occiput, postgena, genal dilation dark metallic bronze-green in ground colour, frontal plate sometimes narrowly metallic bronze-green along the frontal setae, ocellar triangle mostly black. Palpus deeply black (charcoal) or dark brown in older bleached specimens. Prementum black, labella brown. Thorax and abdomen metallic dark olive green in ground colour, shine depending on the direction of the incidence of light; covered with greyish white microtomentum. The intensity of the microtomentum varies, some specimens having more matt appearance than others and in general the microtomentum in males is more dominant than in females. The intensity of the green colouration is variable, some specimens are more lucid green while others, especially from cooler locations, are very dark, almost blackish green. Scutum, when viewed from the side and slightly from behind, with four longitudinal stripes of microtomentum, changing from grey to purple depending on the direction of the incident light. In aged specimens, caught late in the season, the microtomentum can be worn out and give the specimens a polished appearance for the most dorsal part of scutum and postpronotum. Proepisternum black and densely covered with microtomentum. Fore coxa in anterodorsal region and sometimes also femora with remnants of metallic shine, covered with light grey microtomentum. Wing membrane around crossvein r-m narrowly (sometimes somewhat indistinctly) infuscate. Tegula and basicosta black.
Head (Fig.
Thorax : Prosternum bare. Scutum with 3(2)+3 acrostichal, 3(2)+4 dorsocentral and 1+3 intra-alar setae. Ground vestiture on scutum (consisting of thin setulae) dense and erect, longest setulae subequal to the shortest setae. Scutellum normally with four (rarely five) pairs of strong marginal setae, the subapical pair sometimes inserted close to apex, a tiny pre-basal seta present at least on one side; normally four suberect preapical discal setae, forming a row in front of the marginal setae, the strongest pair in the middle sometimes subequal to the lateral setae, mixed with numerous tiny setulae the longest at least 1/5 as long as the strong preapical setae.
Legs : Claws and pulvilli on fore legs ca. 1.1–1.2 (n = 5) × as long as tarsal segment 5, the latter 2.0–2.1 (n = 5) × as long as tarsal segment 4. Fore tibia with a row of 4–6 anterodorsal setae and two or three thin setulae, 4–7 setae/setulae in an irregularly posterior or posterodorsal position (often two or three of them representing setae but sometimes only five tiny setulae present): preapical anterodorsal seta well developed, subequal with the preapical dorsal and preapical posterior setae. Mid tibia with a row of 4–6 anterodorsal setae the strongest in the middle, 2–4 posterodorsal setae (at least two are strong), two posterior setae, one ventral seta often accompanied by a tiny setula. Hind tibia with equally long preapical anterodorsal and posterodorsal setae, apical posteroventral seta ca. 1/2 length of the anterioventral seta; a continuous irregular row of 8–11 anterodorsal setae / setulae of which 4–6 represent strong setae, three or four posterodorsal setae and two or three anteroventral setae.
Wing : Usually two costal spines (rarely one or three), the strongest lower spine ca. 3 × as long as the surrounding costal setulae, normally only somewhat shorter than crossvein r-m. Fourth and fifth costal section 1.8–2.1 (n = 6) × as long as sixth costal sector. Vein R4+5 with 3–7 ventral and 2–9 dorsal setulae (in one deviating specimen with nine setulae almost reaching r-m). Cell r4+5 often somewhat narrowly open at wing edge, 0.50–0.75 × the length of crossvein r-m.
Abdomen (Fig.
Terminalia
(4 dissections) (Figs
Female (Figs
Colouration : Fronto-orbital plate almost entirely metallic bronze-green when viewed from behind and slightly from above; the metallic ground colour at least partly interrupted on the upper part of parafacial, sometimes in patches reaching the level of the lowermost frontal setae. However, most of the metallic ground colour on upper part of parafacial and anterior 1/3 of fronto-orbital plate is covered by greyish white microtomentum, dense especially along eye margin and frontal setae, but when viewed from side and slightly from above with golden reflections. Thorax and abdomen dark metallic green to bronze-green, microtomentum normally thinner than in males, most intense on the pleura and episternum.
Head (Fig.
Legs : Claws and pulvilli on fore legs shorter, ca. 0.7–0.8 (n = 5) × as long as tarsal segment 5, the latter 1.5–1.6 (n = 5) × as long as tarsal segment 4.
Abdomen
: Ground vestiture dorsolateral on tergites 3 and 4 distinctly prone contrasting to the erected setulae between the median discal setae. Tergites 3 and 4 with two or three pairs of median discal setae. Sternite 5 somewhat elongated, 1.1–1.2 × as long as its maximal width (Fig.
Terminalia
(2 dissections) (Fig.
The Co1 DNA barcode sequence of G. lucida differs markedly from the other European species of Gymnocheta (Fig.
Maximum likelihood tree of the Co1 sequences of the Nordic Gymnocheta spp. and related Ernestiini. Numbers at nodes indicate posterior probabilities and scale bar the relative sequence divergence. BOLD progress ID given before the species name and sample ID as well as GenBank access number given after it. The DNA barcodes do not differ between the Nordic G. zhelochovtsevi and G. viridis (BOLD:ACA6555) but differ significantly from G. lucida (BOLD:ACF3891) and G. magna (BOLD:ACA9848).
Gymnocheta lucida was previously known only from the Russian Far East and Japan (
Almost all Finnish records of G. lucida are from ombrotrophic raised bogs. The only exception is the record from Rovaniemi, Lapland (Finland), collected from a pine forest habitat. However, it is typical that insect species that are specific to bogs or moorlands in the south extend their habitat preferences to open forests or heathlands in the north. Gymnocheta viridis is also sometimes recorded from bogs, so the habitat is not a reliable indicator for the species. Similarly, the habitats in Uppland are best described as ombrotrophic bogs separated by different types of coniferous woodlands. The bogs partly covered with dwarfed pine trees, and a scrub layer dominated by Vaccinium uliginosum, Rhododendron tomentosum, Myrica gale, Calluna vulgaris, and Betula nana. The coniferous area surrounding the bogs consists discontinuously of rocky outcrops densely covered by different lichens, i.e., Cladonia sp. and Cetraria islandica, and old pine trees, and sinks also with old pine trees and single spruces; the scrub layer here is dominated by Vaccinium myrtillus but also with elements of Vaccinium vitis-idaea, Rhododendron tomentosum, and Vaccinium uliginosum. The three collection sites of Kallkällmyran, Keutatjape, and Sasnnekape are located just south of the Arctic Circle in Jokkmokk, Lule Lappmark (Sweden). They have been described as rich to medium rich fens in the coniferous zone near Jokkmokk (
Males appear in late May and individuals are first and foremost observed in small sunlit clearings in the sinks between the rocky outcrops, sitting on leaves and twigs of blueberries apparently watching for approaching females. Some of these clearings likely represent hot spots for aggregation. These are frequently attended by males that fly out sporadically from time to time in response to another passing male, but in one of these hot spots mating was observed on two occasions. One male was collected when visiting the flowers of Rhododendron tomentosum. Females appear around second week of June and they are, apart from the ones observed in copula, found on the edge of the bogs close to the rocky outcrops. They have been observed between late June to mid-July in characteristic slow, searching flight, low in the vegetation often just a couple of inches above the moss layer, examining tufts of sedges and shrubs, such as Vaccinium uliginosum and Betula nana. The hosts are currently unknown but concealed larvae of Noctuidae or Erebiidae (Lepidoptera), living in the habitats described above, are most likely.
Gymnocheta magna
Zimin, 1958: 53. Lectotype ♂ [
Russia: Lectotype ♂, by designation of
Diagnosis. A lucid green Gymnocheta species with a notably protruding lower facial margin and green femora. This is also the only European Gymnocheta species with short costal spines.
[values in brackets refer to the holotype of T. viridis Fallén]. Body length: 7.8–12.1 [12.1] mm (n = 10).
Male (Figs
Colouration : Head covered with a greyish white microtomentum. The metallic ground colour subshiny on the genal dilation but the shine/intensity is depending on the direction of the incident light. Facial plate with a greyish white microtomentum; lower protruding area however with a distinct mint metallic green tint. Occiput, postgena, genal dilation, ocellar tubercle metallic green in ground colour. Fronto-orbital plate narrowly but mostly distinctive mint metallic green along the frontal row of setae. Palpus, clypeus (sometimes with a metallic green tint) and prementum dark brown to black, labella brown beige. Thorax and abdomen bright mint metallic green in ground colour, contrasting with gilt or purple lustre depending on the direction of the incident light, with an indistinct greyish white microtomentum. Scutum when viewed from the side and slightly from behind with four longitudinal stipes changing from grey to gilt or purple depending on the direction of the incident light. Proepisternum normally with the metallic green ground colour subshiny, but less so in dwarfish specimens. Fore coxa in anterior region and femur posteriorly mostly with a metallic green shine. Wing membrane around crossvein r-m rarely infuscated. Tegula and basicosta dark brown or black.
Head (Figs
Thorax (Fig.
Legs : Claws and pulvilli on fore legs slightly longer than fifth tarsal segment, the latter 1.7–2.0 (n = 3) × as long as the fourth. Fore tibia with a row of 5–6 anterodorsal setae, and an irregular row of 2–4 posterodorsal and 2 posterior setae; preapical anterodorsal seta subequal with the preapical dorsal seta, preapical posterodorsal seta short, its length rarely exceeding 1/3 of the dorsal seta. Mid tibia with three or four anterodorsal setae, the strongest in the middle of row, five or six posterior (pd and p) setae, one ventral seta often accompanied by an additional tiny setula. Hind tibia with a continuous row of nine or ten unequally strong anterodorsal setae / setulae of which four or five represent strong setae, three or four posterodorsal setae, the lowest one the strongest, and two or three anteroventral setae.
Wing
: (Fig.
Abdomen (Fig.
Terminalia
(two dissections) (Figs
Female (Figs
Colouration : Fronto-orbital plate vivid mint metallic green when viewed from behind and slightly from above; the metallic ground colour continues down on the upper part of parafacial reaching the level of the lowermost frontal setae; the upper part of parafacial and anterior 1/3 of fronto-orbital plate with a thin greyish white microtomentum, visible along eye margin and as a slim line at the edge of frontal vitta. Thorax and abdomen vivid metallic green, at most with thin whitish microtomentum.
Head (Fig.
Legs : Claws and pulvilli on fore legs shorter ca. 0.7–0.8 × as long as tarsal segment 5, the latter 1.5–1.7 × as long as tarsal segment 4.
Abdomen
: Ground vestiture dorsolateral on tergites 3 and 4 distinctly prone contrasting to the erected setulae between the median discal setae. Tergites 3 and 4 normally with two or three pairs of median discal setae, tergites 3 and 4 occasionally devoid of one seta. Sternite 5 (Fig.
Terminalia
: (two dissections) (Fig.
Gymnocheta magna has a unique Co1 barcode sequence, BOLD:ACA9848 (Fig.
Widely distributed in the Palaearctic Region (
The biology of Gymnocheta magna is poorly known. This is a summer species in the Nordic countries with a flight time from early June to mid-July. It is not a heathland specialist as suggested by some sparse records from Central Europe (
Holotype
♂ with a Fallén faded handwritten ink label reading (Fig.
The identity of Tachina viridis Fallén, 1810: 276. Gymnocheta viridis (Fallén, 1810) is the oldest described Gymnocheta and represents the type species of the genus. The Fallén collection, drawer 13 (4), contains a single type specimen (formally the holotype) (Fig.
As a further confirmation of the type specimen identity, the original description in Swedish also refers to a single male: “♂ Denna lysande art, funnen på kummin midsommartiden i Maltesholms trädgård i Skåne, …”. [This brilliant species, found on caraway [Carum carvi] in midsummer time in Maltesholms garden in Skåne, ….] (
Two of these aforementioned non-type specimens are in the
1♀: Labels: Hlm / P.Wg. This is apparently the specimen mentioned by
Three additional non-type specimens are present in the Diptera Scandinaviae Collection, drawer 22 in
For the sake of nomenclatural stability, we propose maintaining the current usage of the names G. viridis and G. magna. Neotype specimen for Gymnocheta viridis will be assigned later if ICZN accepts the petition for the replacement of the holotype. The following redescription represents G. viridis in its prevailing concept.
A common, vivid metallic green Gymnocheta with strong costal spines and narrow frons in male.
Body length: 7.2–10.8 mm (n = 19).
Male (Figs
Colouration : Head covered with a greyish white microtomentum. The metallic ground colour subshiny at least partly on the genal dilation but the intensity of the shine depends on the direction of the incident light. Facial plate brown, in lower part sometimes with an indistinct metallic green tint. Occiput, postgena, genal dilation, ocellar tubercle metallic green in ground colour, frontal plate narrowly metallic green along the frontal setae. Palpus, clypeus (sometimes with a metallic green tint) and prementum dark brown to black, labella brown beige. Thorax and abdomen bright metallic green in ground colour, in varying degrees depending on the direction of the incident light with an indistinct light grey microtomentum. Scutum when viewed from the side and slightly from behind with four longitudinal stripes changing from grey to gilt or purple depending on the direction of the incident light. Proepisternum normally black, and densely covered with microtomentum, in larger specimens partly with a metallic green tint. Fore coxa in anterior region and femur posteriorly often with weak metallic green shine. Wing membrane around crossvein r-m not infuscated. Tegula and basicosta dark brown or black.
Head (Fig.
Thorax : Prosternum bare. Scutum with 3(2)+3 [3+3] acrostichal, three or four dorsocentral and 1+3 intra-alar setae. Scutellum with 4(5) pairs of strong almost horizontal setae along margin, apical and subapical pairs slightly diverging; 2–4 [2] suberect discal setae, forming a row in front of the marginal setae, the strongest subequal to the lateral setae, rarely with an additional pair of strong median discal setae; tiny dorsal setulae numerous, the longest measuring 1/2 the length of the strongest dorsal seta.
Legs : Claws and pulvilli on fore legs subequal in length with fifth tarsal segment, the latter 1.8–2.0 (n = 6) × as long as tarsal segment 4. Fore tibia with a row of 5–8 [five and six] anterodorsal setae, and an irregular row of 4–8 [6] posterior setae. Preapical anterodorsal seta subequal with the preapical dorsal and preapical posterior setae; preapical posterodorsal seta short, its length rarely exceeding 1/3 of the dorsal seta. Mid tibia with 4–6 [4] anterodorsal setae, the strongest in the middle of row, 5–8 [7] posterior setae, one ventral seta often accompanied by an additional tiny setula. Hind tibia with a continuous row of 9–12 unequally strong anterodorsal setae / setulae, of which 4–6 represent strong setae, four or five posterodorsal setae and three (rarely four) anteroventral setae.
Wing : Usually two costal spines, the lower (ventral) spine strongest and ca. 2–3 × as long as the surrounding costal setulae, normally somewhat shorter than crossvein r-m. CS4 + CS5 2.1–2.4 (n = 12) × as long CS6. Vein R4+5 at base with 3–6 [three and four] ventral and 3–8 [4] dorsal setulae.
Abdomen (Fig.
Terminalia
(five dissections) (Figs
Aedeagus: Distiphallus in lateral view of almost uniform width.
Female (Figs
Colouration : Fronto-orbital plate vivid metallic green when viewed from behind and slightly from above; the metallic ground colour continues down on the upper part of parafacial reaching the level of the lowermost frontal setae; the upper part of parafacial and anterior 1/3 of fronto-orbital plate with a thin greyish white microtomentum, visible along eye margin and as a slim line at edge of frontal vitta. Thorax and abdomen vivid metallic green at most with a thin whitish microtomentum.
Head
(Fig.
Legs : Claws and pulvilli on fore legs shorter ca. 0.7–0.8 × as long as tarsal segment 5, the latter 1.5–1.7 × as long as tarsal segment 4.
Abdomen : Tergites 3 and 4 normally with two pairs of median discal setae, tergite 3 rarely missing one seta or with one additional seta, tergite 4 occasionally devoid of one seta. Ground vestiture dorsolateral on tergites 3 and 4 distinctly prone contrasting to the erect setulae between the median discal setae. Tergite 5 trapezoid, along anterior margin ca. 2 × as wide as long. Sternite 5 ca. as long as its maximal width, with 6–10 strong setae in posterior 1/3, four of them along the posterior margin and one or two pairs of median setae, in posterior 1/2 accompanied by numerous (60–70) irregularly spread setulae of varying size.
Terminalia
(four dissections) (Fig.
The European specimens of G. viridis share the Co1 DNA barcode sequence (BOLD:ACF3891) with Finnish G. zhelochovtsevi (Fig.
A widely distributed and common species in the Palaearctic Region, including all of Europe, Japan (Hokkaido, Honshu), Middle East, all of Russia and Transcaucasia (
Gymnocheta viridis is a common spring–early summer species, often numerous at the right locations. Typical habitats include forest margins and meadows, but the species is frequently seen also in gardens. The males start their flight in early April in Central Europe and around end of April to early June in the north. The last female records in Finland are from mid-July. Males are frequently observed basking on tree trunks and watching for passing females. Both sexes can be collected from flowers, especially on cow parsnip (Anthriscus sylvestris), but also from other Daucaceae. The species is a known parasitoid of Erebidae (Lepidoptera) living in grass tufts, such as Mesapamea secalis Linnaeus and Photedes minima Haworth (
Gymnocheta zhelochovtsevi
Zimin, 1958: 62. Holotype ♂ [
Russia: ♂: Южные Курилы, Итуруп, Рыбаки, 5 км SW Курильска, В. Рихтер, 23. VI.1968 [Southern Kurils, Iturup, Ribaki, 5 km SW Kurilsk, V. Richter, 23. VI.1968], det. V. Richter. Dissected by V. Richter [
Gymnocheta zhelochovtsevi is characterised by a dark, almost black metallic green, wide frons in both sexes, and a hooked syncercus in the male.
Redescription. Body length: 9.2–10.4 mm (n = 7).
Male (Figs
Colouration : Head covered with dense greyish or yellowish white microtomentum. The metallic ground colour is only weakly shining through, similar as is seen with G. lucida. Facial plate black without a metallic green spot. Occiput, postgena, genal dilation, ocellar triangle and frontal plate almost black in ground colour, although a hint of dark metallic bronze-green shine can be seen with changing light incidence. Palpus clypeus and prementum black, labella dark brown. Thorax and abdomen dark metallic green in ground colour, not as lucid as in G. magna or G. viridis and covered with indistinct greyish white microtomentum. Scutum, when viewed from the side and slightly from behind, with four pronounced longitudinal stripes of microtomentum, changing from grey to purple depending on the direction of the incident light. Proepisternum black and with thin grey microtomentum. Legs extensively black, but fore coxa in anterodorsal region and sometimes also femora with remnants of metallic shine, covered with light grey microtomentum. Wing membrane around crossvein r-m not infuscated.
Head (Fig.
Thorax : Prosternum bare. 2(3)+3 acrostichal, 3+4 dorsocentral and 1+3 intra-alar setae. Ground vestiture on scutum (consisting of thin setulae) sparse and erect, longest setulae 0.5–0.6 × as long as the shortest setae, anteriorly shorter, at most 0.3 × the length of the setae. Scutellum with four pairs of strong marginal setae, mixed with some shorter and weaker marginal setae/setulae, almost horizontal with the plane of scutellum, apical setae missing; subapical setae close to the apex, parallel or slightly diverging, two lateral pairs and one basal pair; four suberect preapical discal setae, forming a row in front of the marginal setae, the strongest pair in the middle sometimes subequal to the lateral setae, mixed with numerous tiny setulae the longest at least 1/2 as long as the strong preapical setae.
Legs : Claws and pulvilli on fore legs ca. 1.0 (n = 3) × as long as tarsal segment 5, the latter 2.0 (n = 3) × as long as tarsal segment 4. Fore tibia with a row of 5–7 anterodorsal setae, 3–5 setae in an irregular posterodorsal row and two posterior setae; preapical anterodorsal seta well developed, subequal with the preapical dorsal and preapical posterior setae. Mid tibia with a row of five anterodorsal setae the strongest in the middle, four or five posterodorsal setae, two or three posterior setae, one strong ventral seta accompanied by a shorter seta above. Preapical anterodorsal seta of the hind tibia subequal to the preapical dorsal seta, preapical anteroventral seta 1/2 the length of anterodorsal seta; a continuous irregular row of 8–10 anterodorsal setae, three or four posterodorsal setae and three or four anteroventral setae.
Wing : One or two costal spines, the strongest lower spine 2–3 × as long as the surrounding costal setulae. Fourth and fifth costal section ca. 2 × as long as sixth costal sector. Vein R4+5 at node with four ventral and three or four dorsal setulae. Cell r4+5 often somewhat narrow at wing edge, 0.8 × the length of crossvein r-m.
Abdomen (Fig.
Terminalia
(three dissections) (Figs
Sternite 5 (Fig.
Female (Figs
Colouration : Fronto-orbital plate almost entirely metallic dark green when viewed from behind and slightly from above; the metallic ground colour at least partly interrupted on the upper part of parafacial. However, most of the metallic ground colour on upper part of parafacial and anterior 1/3 of fronto-orbital plate is covered by greyish white microtomentum, which is dense especially along eye margin and frontal setae.
Head (Fig.
Thorax : Whitish grey microtomentum normally thinner than in males, most intense on the pleura and episternum.
Legs : Claws and pulvilli on fore legs shorter ca. 0.7–0.8 (n = 5) × as long as tarsal segment 5, the latter 1.5–1.6 (n = 5) × as long as tarsal segment 4.
Abdomen
: Tergites 3 and 4 with one or two pairs of median discal setae. Tergite 5 trapezoid, along anterior margin ca. 2 × as wide as long, posterior edge concave (blunt or pointed in G. lucida). Sternite 5 slightly wider than long, with 4 strong setae along posterior margin (Fig.
Terminalia
(one dissection) (Fig.
Despite the morphological differences, G. zhelochovtsevi shares Co1 DNA barcode sequence with G. viridis (Fig.
Like G. lucida, G. zhelochovtsevi had been thought to be an Eastern Palaearctic species (
The specimens from Halikko were collected from a flood meadow adjacent to a meandering stream. The meadow is characterised mainly by tall grass and sedges, surrounded by shrub of willows (Salix spp.) and bird cherry (Prunus padus L.). One male and one female were hand netted from the flowers of Anthriscus sylvestris (L.) and two females were collected with a Malaise trap. The female specimen from Korppoo was caught in a Malaise trap in a seashore meadow, surrounded by shrub of meadowsweet (Filipendula ulmaria (L.)) and alders (Alnus spp.). The Swedish specimen was collected in a Malaise trap, placed close to the calmly flowing, slightly meandering, ca. 5 m wide Tavelån River. The trap was placed in overgrowth known as “raningsmark”; i.e., grassland long ago used as a hay meadow or grazing but now characterised by bush wood with meadow glades between the shrubbery.
Lauri Tiensuu mentioned on page 138 of his unpublished notes that a specimen identified by him as a female of G. viridis, but actually a male of G. zhelochovtsevi, was collected around (on?) aspen (Populus tremula L.) trunks near the village of Salmenkylä in the former municipality of Vehkalahti. The original description by Zimin was based on one male specimen, whose fifth sternite was poorly illustrated and the epandrium not illustrated at all in the original publication. The tip of the syncercus of the species has a characteristic hook (Figs
This identification key is based on the ones provided by
1 | Cell r4+5 short-stalked, closed, or rarely narrowly open at wing margin; appendage at bend of vein M equal to or slightly shorter than distance between crossvein dm-cu and bend; body slender, shining, dark olive green; length of external costal spine equal to length of crossvein r-m, width of frons > 1/2 as wide as an eye [Not seen. Female unknown] | Gymnocheta mesnili Zimin |
– | Cell r4+5 open, other combinations of features | 2 |
2 | Abdomen cherry-red or wine red | 3 |
– | Abdomen green | 4 |
3 | Scutum with 4 brownish black, distinct narrow longitudinal vittae separated by wide areas of thin white microtomentum, distinct in the presutural part of scutum. Frons in dorsal view 0.25–0.33 × the width of an eye in males and 0.66 × in females. Lower facial margin in lateral view distinctly protruding between the vibrissae. Male sternite 5 as in Fig. |
Gymnocheta porphyrophora Zimin |
– | Frons in male narrow, 0.20–0.25 × the width of an eye. Apex of syncercus not wider than apex of surstylus (caudal view), labella small-sized [Not seen. Female unknown] | Gymnocheta flamma Zimin |
4 | Males | 5 |
– | Females | 8 |
5 | Frons in dorsal view 0.5–0.7 × the width of an eye (Fig. |
Gymnocheta zhelochovtsevi Zimin |
– | Frons in dorsal view either not exceeding 0.4 × the width of an eye, and frontal vitta gradually narrowing towards ocellar tubercle (G. magna and G. viridis), or frons wider (G. lucida), but then frontal vitta narrowing towards middle. Frontal vitta at level of ocellar tubercle at most twice the width of the orbital plate. Occiput at least mediodorsally with a shiny metallic green colour. Outer vertical seta weaker than the inner, subequal to the postocellar setae | 6 |
6 | Frons in dorsal view at its narrowest point, 0.43–0.51 × width of an eye (Fig. |
Gymnocheta lucida Zimin |
– | Frons in dorsal view rarely exceeding 0.4 × width of an eye. Frontal vitta gradually narrowing towards ocellar tubercle. Fronto-orbital plate, parafacial, and genal dilation with a thin greyish white or white microtomentum but the metallic green colour subshiny at least at the fronto-orbital plate. Thorax and abdomen more bright green, sometimes with a golden- or blue green lustre. Scutum with thin microtomentum. Arista normally widened in less than proximal 1/2. Proepisternum usually partly metallic green | 7 |
7 | Lower facial margin slightly protruding (Fig. |
Gymnocheta viridis (Fallén) |
– | Lower facial margin strongly or moderately protruding (Figs |
Gymnocheta magna Zimin |
8 | Frons in dorsal view 0.8–1.0 × as wide as an eye (Fig. |
Gymnocheta zhelochovtsevi Zimin |
– | Frons normally not exceeding 0.9 × the width of an eye. Frontal vitta either gradually tapering towards ocellar tubercle or narrowest at ca. middle. Scutum either with 4 greyish white longitudinal stripes or when viewed from different directions with 4 dark stripes covered by thin microtomentum. Occiput in upper part behind the row of postocular setulae and fronto-orbital plate at least in their upper part metallic green, without microtomentum | 9 |
9 | Thorax and abdomen metallic olive green; viewed from different directions notably scutum with a bronze or golden lustre. The greyish white microtomentum in anterior part of fronto-orbital plate shifting into a bronze or golden lustre when viewed from different directions. Frontal vitta tapering towards middle, then slightly widening towards ocellar tubercle. Width of first flagellomere normally wider than parafacial at narrowest point. Arista widened in at least its basal 1/2, sometimes almost in proximal 2/3 and gradually tapering to apex. Cell r4+5 narrowly open, or (as an exception) closed at wing margin. Terminalia as in Figs |
Gymnocheta lucida Zimin |
– | Thorax and abdomen bright metallic green; viewed from different directions with purple lustre. The greyish white microtomentum in anterior part of fronto-orbital plate sometimes shifting into a silvery lustre. Frontal vitta gradually tapering towards ocellar tubercle. Width of first flagellomere not exceeding width of parafacial at narrowest point. Arista normally widened in less than proximal 1/2. Cell r4+5 wide open at wing margin | 10 |
10 | Lower facial margin hardly protruding between vibrissae (Fig. |
Gymnocheta viridis (Fallén) |
– | Lower facial margin distinctly protruding between vibrissae (Fig. |
Gymnocheta magna Zimin |
We are grateful to Dr. Takuji Tachi (