Biodiversity Data Journal :
Taxonomic Paper
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Corresponding author: Jostein Kjærandsen (jostein.kjarandsen@uit.no)
Academic editor: Vladimir Blagoderov
Received: 28 May 2020 | Accepted: 10 Aug 2020 | Published: 10 Sep 2020
© 2020 Jostein Kjærandsen, Alexei Polevoi, Jukka Salmela
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:
Kjærandsen J, Polevoi A, Salmela J (2020) Coelosynapha, a new genus of the subfamily Gnoristinae (Diptera: Mycetophilidae) with a circumpolar, Holarctic distribution. Biodiversity Data Journal 8: e54834. https://doi.org/10.3897/BDJ.8.e54834
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The subfamily Gnoristinae is one of the most diverse and taxonomically difficult subfamilies of Mycetophilidae, with new species and genera being described almost every year from various parts of the world. Through inventories of fungus gnats in the Nordic Region and Russia, a genus and species new to science was discovered, yet with links back to an illustration made by the late French entomologist Loïc Matile in the 1980s. DNA barcoding aligned it with yet another species new to science, distributed across Canada and documented through The Barcode of Life Data System (BOLD) by Paul D. N. Hebert and colleagues at the BOLD team.
The new Holarctic genus, Coelosynapha gen. n. is described, consisting of two new species, the Palaearctic Coelosynapha loici sp. n. and the Nearctic Coelosynapha heberti sp. n. DNA-barcodes assign the two new species to distinctly separated (8.27% p-distance) Barcode Index Numbers (BINs) which are most closely aligned to unidentified species of Mycetophilidae from South Australia and Costa Rica on BOLD. The new genus shows morphological characteristics in between the two Holarctic genera Coelosia Winnertz, 1864 and Synapha Meigen, 1818 and further shows affinity to the southern continents genus Austrosynapha Tonnoir, 1929. The Palaearctic Coelosynapha loici sp. n., for which habitat requirements are best documented, is largely restricted to pristine, old-growth conifer (mostly spruce, Picea abies ssp. obovata) forests within the boreal vegetation zone, although it is also recorded from hummock tundra along the Anadyr River in Far East Russia.
Coelosynapha, Mycetophilidae, Gnoristinae, new genus, new species, DNA barcoding, Holarctic distribution, old-growth conifer forests.
According to
The current case concerns an undescribed genus known from the high north of Fennoscandia, from the Altai mountains and Far East Chukotka in Russia and from across southern Canada, i.e. a circumpolar taxon. Some 25 years ago, Geir E. E. Søli at the Natural History Museum in Oslo was made aware of an enigmatic species belonging to the subfamily Gnoristinae of the family Mycetophilidae when the late French entomologist Loïc Matile (1938-2000, see
Specimens of the new taxon from Fennoscandia and Russia were submitted for barcoding and their automated Barcode Index Number (BIN) (
The subfamily Gnoristinae appears to be amongst the most difficult branches of the Mycetophilidae to classify. Phylogenies (e.g.
The studied specimens were collected over a period from 2009 to 2016 from 12 localities in North America and Eurasia (Fig.
The 658 bp fragment of the mitochondrial protein-encoding cytochrome c oxidase subunit I (COI) was sequenced from a total of 10 Coelosynapha loici sp. n. specimens and five C. heberti sp. n. specimens. One leg from each fresh specimen was sent to the Canadian Centre for DNA barcoding, BIO (Guelph, Ontario, Canada), for DNA extraction and bi-directional Sanger sequencing as a part of the Norwegian Barcode of Life (NorBOL) (see
A Leica MC170HD microscope camera, mounted on a Leica M205C stereomicroscope, was used to capture images of whole specimens and of detached terminalia macerated in hot lactic acid and stored in glycerine. Stacked images, merged for extended focus applying the Helicon Focus software, were subsequently moderately photo-shopped into illustrative plates. Digital illustrations (Fig. 10) were made with Inkscape vector drawing editor (http://inkscape.org).
The general terminology of body, wings and terminalia follows
A Gnoristinae genus, as presently known with moderately slender and quite small, down to 3 mm body length, species (Figs
Variation in wing venation of males of Coelosynapha loici sp. n. Note the substantial variation in the radial sector ranging from R2 and R3 being absent to separated to a variable degree of fusion into R2+3. Variation in these characters are also apparent between left and right side in some specimens. Abbreviations: A = anal veins (numbered); CuA = anterior branch of cubital vein; CuP = posterior branch of cubital vein; h = humeral vein; iCu = intercubital fold (not a vein); M = medial veins (numbered); R = radial veins (numbered); r–m = radial–medial crossvein; Rs = radial sector; sc = subcostal vein; tb = basal transversal.
Variation in wing venation of Coelosynapha heberti sp. n. Note the substantial variation in the radial sector ranging from R2+3 being absent or present. Note also the appearance of sc–r in one female wing, while all the others are lacking this crossvein. The most prominent difference in the wings of the two species appears to be the relatively longer posterior fork with basally less curved M4 in Coelosynapha heberti sp. n. Abbreviations: R = radial veins (numbered); sc–r = subcostal–radial crossvein.
Female terminalia (Fig.
Male terminalia (Figs
A Gnoristinae genus similar to Austrosynapha Tonnoir, 1929, Coelosia Winnertz, 1864 and Synapha Meigen, 1818 in general appearance, but with very characteristic and unique male terminalia with three blunt, digitate processes apically on the gonostyles (Figs
The generic name is feminine gender and put together by the two genus names Coelosia Winnertz, 1864 and Synapha Meigen, 1818, indicating the affinity to and intermediate position between those two genera.
Records of the new genus display a circumpolar distribution pattern from Fennoscandia to Far East Russia in the Palaearctic Region and across Canada in the Nearctic Region (Fig.
Male. (Figs
Stacked images of details of terminalia of Coelosynapha loici sp. n. Terminology of gonostylus parts: a = dorsal finger, b = median finger, c = ventral finger, d = lateral finger, e = ventral comb, f = ventromedial cushion of setulae, g = medial bristle 1, h = medial bristle 2.
Head (Fig.
Thorax (Fig.
Wings (Fig.
Legs. Legs yellow with a brown tinge on trochanter, tibia and tarsi. Fore tarsus 1 slightly longer than fore tibia (ratio 1.06 in holotype).
Abdomen. Abdominal tergites and sternites brown, bearing light hairs. Tergites 7 and 8 rudimentary in size, sternite 8 lingulate.
Terminalia (Figs
Aedeagus inconspicuous, parameres fused.
Female unknown.
Coelosynapha loici sp. n. is named in honour of the late French entomologist Loïc Matile (1938–2000) who first studied the new species and illustrated its terminalia (Fig.
The new species has a wide Palaearctic range in boreo-mountainous localities, it has been collected from the High North boreal forest of Fennoscandia (Norway, Finland, NW Russia), from a high mountain site in Asian part of Russia and from hummock tundra in Far East Russia, at a total of seven localities (Fig.
Six of the collecting sites are within the boreal vegetation zone while the record from Chukotka is from the low arctic ecoregion. The European sites, one in Norway, three in Finland, one in Russia, are all northern boreal, close to the range limit of spruce (Picea abies ssp. obovata), lying some 140-180 km north of the arctic circle. All European collecting sites are pristine, boreal old-growth forests, dominated by spruce or occasionally pine (Reisadalen NP) and with scattered deciduous trees (birch, Betula pubescens and goat willow, Salix caprea). The ground layer is characterised by mosses, especially Pleurozium schreberi and bilberry (Vaccinium myrtillus). Malaise traps on these sites have been set in the vicinity of springs or cold headwater streams. The specimens from Altai were collected at an altitude of 2144 m above sea level in steppe type Larix forest. The Chukotka specimen was collected with a yellow pan trap set in hummock tundra along the Anadyr river at 5-10 m above sea level.
Male.(Figs
Stacked images of details of terminalia of Coelosynapha heberti sp. n. Terminology of gonostylus parts: a = dorsal finger, b = median finger, c = ventral finger, d = lateral finger, e = ventral comb, g = medial bristle 1, h = medial bristle 2.
Colouration and most body characteristics (Fig.
Wings (Fig.
Terminalia (Figs
Female. (n = 4)
Colouration as for male.
Wings (Fig.
Terminalia (Fig.
Coelosynapha heberti sp. n. is named in honour of Paul D. N. Hebert, "the father" of DNA barcoding who also led the project of barcoding the insects of Canada (
The new species has a wide Nearctic range across Canada (Fig.
Section of the generic key to separate Coelosynapha and Coelosia Couplet 1 corresponds to the couplet 68 in the key by |
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1 | Point of furcation of posterior fork (veins M4 and CuA) distinctly beyond point of furcation of anterior fork (veins M1 and M2) | 2 |
– | Point of furcation of posterior fork (veins M4 and CuA) before, below or slightly beyond point of anterior fork (veins M1 and M2) |
Couplet 69 in the key by |
2 | Stem of anterior fork more than 2x longer than crossvein r–m, R2+3 present or absent, crossvein sc–r present or absent | Coelosynapha gen. n. |
– | Stem of anterior fork at most slightly longer than crossvein r–m, R2+3 always absent, Crossvein sc–r always absent | Coelosia Winnertz, 1864 |
The enormous success of DNA barcoding now has accumulated a substantial amount of sequenced insects on BOLD, very useful for new and integrative taxonomic studies. More than 65,000 specimens belonging to the family Mycetophilidae have been successfully sequenced and, of them, some 10,000 are assigned to the subfamily Gnoristinae. Some 1100 identified Mycetophilidae species have public barcodes although more than 2400 different BINs are assigned, thus indicating that the majority of the species still remains unidentified beyond the (sub)family level on BOLD. A weakness with the BOLD initiative may be that several of the typically well-funded, large scale DNA barcoding projects, undertaken so far, did not have a focus on, nor adequate resources allocated to, securing high quality morphological identification of the vouchers for the accumulated barcodes. Unfortunately, this critical endeavour of the BOLD archive is largely left to the under-funded and scarce taxonomic expertise to engage in "post-sequence" at will.
In the Nordic region, however, strong ties between The Norwegian and Swedish Biodiversity Information Centres, including their Taxonomy Initiatives and NorBOL and FinBOL, are ensuring that the best taxonomic expertise is building up the reference library of the local fauna on the BOLD archive. Hence, the vast majority of some 6500 DNA barcoded fungus gnats (Sciaroidea) from the Nordic region have been identified to species level upon submission and the reference library is profoundly and repeatedly quality-checked and curated after barcodes and BINs are assigned. This has resulted in a high quality reference library, now covering about 90% of the known fauna and more than 100 additional species considered to be new to science (
ID-tree (Kimura-2-distance) obtained from BOLD of DNA barcodes of Coelosynapha gen. n. and close allies.
Coelosynapha loici sp. n. is assigned to the BIN BOLD:ADD0785, consisting of 10 members with a maximum within-species genetic distance of 0.72%. Coelosynapha heberti sp. n. with five members assigned to BIN BOLD:ACI5160 likewise has a maximum within-species genetic distance of 0.72%. The reciprocal nearest-neighbour distance between the two is 8.27–8.66% (depending on direction). A barcode gap analysis of the distance between Coelosynapha loici sp. n. and close genera reveals the closest Coelosia being Coelosia truncata Lundström, 1909 at 13.67%, the closest Synapha being Synapha fasciata Meigen, 1818 at 15.36% and the sole determined Austrosynapha sp. on BOLD (sp. JSGS1, mined from GenBank) at 16.79% distance.
The variation seen in the radial sector of the wing in species of Coelosynapha gen. n. is not unique. Several Gnoristinae genera show variation in exactly this character, including Grzegorzekia Edwards, 1941, Speolepta Edwards, 1925, Synapha and Syntemna Winnertz, 1864, to a point where the instability is almost a characteristic of parts of the subfamily. None of these genera, however, appears to be very closely related to Coelosynapha gen. n. as revealed by COI haplotype similarities.
There are indications that both Synapha and Austrosynapha, as presently defined, are polyphyletic genera in need of revision, but it is beyond the scope of this paper to address these issues pending a more thorough revision of the entire subfamily. Here we have added another genus that, if included in either of them or in Coelosia, would likely render them even more para- or polyphyletic. We hope that describing Coelosynapha gen. n. will give new insights and inspire further phylogenetic studies of the fascinating, but intriguing subfamily Gnoristinae.
Insect collecting surveys throughout northern Norway by JK were supported by UiT – The Arctic University of Norway and The Norwegian Biodiversity Information Centre under the project grants “North-eastern elements of the Norwegian fauna of fungus gnats” (2015-17, project grant 70184233/45-14) and “Fungus gnats in karst landscapes of Nordland – adding up the fauna of Northern Norway” (2018-20, project grant 70184238/27-17). The work of AP was carried out under state order implemented by Karelian Research Centre RAS (Forest Research Institute). We are very grateful to Geir Søli at the Natural History Museum in Oslo for sharing with us the illustration of Coelosynapha loici sp. n. made by Loïc Matile (Fig. 1) and for commenting on a draft of the manuscript. Further, we are very grateful to Paul D. N. Hebert and the BOLD team for lending us materials of Coelosynapha heberti sp. n. and for inspiring us to extended research on the Holarctic fauna of fungus gnats by sharing openly the huge dataset of Canadian DNA-barcodes. We also thank Anatoli Barkalov (Novosibirsk, Russia) for the opportunity to study his materials from Chukotka and Elena Subbotina (Tomsk, Russia) for the information on the specimens from Altai.
JK, JS & AP all collected materials of Coelosynapha loici sp. n.
JK & JS submitted samples to BOLD and retrieved and studied specimens of Coelosynapha heberti sp. n. form BOLD.
JK & AP made the illustrations.
JK, JS & AP all analysed the materials, wrote the descriptions and manuscript.
The headings are listed with process ID on BOLD, species name, specimen code, country, state/region, mitochondrial gene region, BIN and, when available, GenBank index number.