Cheilosia ( Cheilosia ) gemmula, Bot & Mengual & Meutter & Skevington, 2025

Bot, Sander, Mengual, Ximo, Meutter, Frank Van de & Skevington, Jeffrey H., 2025, Review of the genus Cheilosia Meigen, 1822 (Diptera: Syrphidae) from the Caucasus, with the description of 14 new species, European Journal of Taxonomy 1023, pp. 1-181 : 58-62

Cheilosia ( Cheilosia) gemmula sp. nov.

urn:lsid:zoobank.org:act:

Figs 29–30

Differential diagnosis

Cheilosia gemmula sp. nov. has a combination of characters found only in a few other species: eye black pilose, face bare, legs black, scutellum with setae on posterior margin and sterna shiny. Nevertheless, our new species is smaller than all similar species ( 5.5–8.5 mm). It is similar to C. vernalis but it differs by black legs and black postpedicel ( Fig. 30A–B) (in C. vernalis legs and usually also postpedicel bicoloured, black and orange), arista bare with thickened basis (without thickened basis in C. vernalis ), face shinier and parafacia wider. Cheilosia gemmula is similar to C. caucasi sp. nov. but smaller ( 5.5– 8.5 mm vs 8–11.5 mm), shinier, pile on eyes longer and black ( Fig. 30A–B) (shorter and partly yellow in C. caucasi ), face, frons and parafacia without pruinosity (more pruinose in C. caucasi ), arista shorter and basis thicker ( Fig. 30A–B) and wings hyaline (black infuscate in C. caucasi ). Moreover, the female of C. gemmula differs from that of of C. caucasi by a long erect mixed black and white pile on the scutum instead of an adpressed predominantly black pile in C. caucasi .

Etymology

The species name ‘ gemmula ’ is a diminutive of the Latin word ‘ gemma ’ meaning ‘gemstone’ or ‘jewel’ ( Brown 1956: 170) and it refers to the small and shiny appearance of the species. Species epithet to be treated as a noun in apposition.

Material examined

Holotype

GEORGIA • ♂; Samegrelo-Zemo Svaneti; 42.911° N, 42.938° E; 2480 m a.s.l.; 27 Jun. 2018; S. Bot leg.; ZFMK, SB.003124 = ZFMK-TIS-8009652 .

Paratypes

GEORGIA – Mtskheta-Mtianeti • 7 ♂♂; Kazbegi Municipality , gravel area 3 km SSE of Kobi; 42.5201° N, 44.5153° E; 2913 m a.s.l.; 31 Jul. 2001; J.-H. Stuke leg.; ZFMK, ZFMK-DIP-00058271 to ZFMK-DIP-00058277 • 18 ♀♀; same data as for preceding; ZFMK, ZFMK-DIP-00058278 to ZFMKDIP-00058295 • 17 ♂♂; Kazbegi Municipality , glacier foot 6 km W of Stepantsminda; 42.6601° N, 44.5565° E; 2800–3000 m a.s.l.; 2 Aug. 2001; J.-H. Stuke leg.; ZFMK, ZFMK-DIP-00058296 to ZFMK-DIP-00058312 • 46 ♀♀; same data as for preceding; ZFMK, ZFMK-DIP-00058313 to ZFMKDIP-00058358 • 1 ♀; Kazbegi Municipality , slopes W of Stepantsminda; 42.6591° N, 44.6366° E; up to 2500 m a.s.l.; 2 Aug. 2001; J.-H. Stuke leg.; ZFMK, ZFMK-DIP-00058359 . – Samegrelo-Zemo Svaneti • 4 ♀♀; 42.911° N, 42.938° E; 2480 m a.s.l.; 27 Jun. 2018; S. Bot leg.; SBA, SB.003125 = ZFMKTIS-8009653 , SB.003126 to SB.003128 ; SBA • 6 ♂♂; 43.028° N, 42.910° E; 2834 m a.s.l.; 13 Jun. 2019; S. Bot leg.; SBA, SB.003129 to SB.003134 • 3 ♀♀; same data as for preceding; SBA, SB.003135 = ZFMK-TIS-8009654 , SB.003136 , SB.003137 • 3 ♂♂, 2 ♀♀; 14 km E of Mestia ; 43.0256° N, 42.8908° E; 2550 m a.s.l.; 13 Jun. 2019; F. Van de Meutter leg; FMT • 1 ♀; 43.0254° N, 42.8906° E; 2550 m a.s.l.; 13 Jun. 2019; X. Mengual leg.; ZFMK, ZFMK-TIS-8008805 = ZFMK-DIP-00066468 • 1 ♂; 43.02° N, 42.89° E; 2600 m a.s.l.; 13 Jun. 2019; J. van Steenis leg.; JSB, 2019-00.958 • 1 ♂; 43.0259° N, 42.9103° E; 2863 m a.s.l.; 13 Jun. 2019; J.H. Skevington leg.; CNC, CNC1386376 • 1 ♀; same data as for preceding; CNC, CNC1386385 • 1 ♀; Latpari Pass ; 42.8816° N, 42.9466° E; 2836 m a.s.l.; 13 Jun. 2019; J.H. Skevington leg.; CNC, CNC1386706 • 1 ♂; 43.0275° N, 42.9115° E; 2887 m a.s.l.; 14 Jul. 2021; S. Bot leg.; SBA, SB.003138 • 9 ♀♀; same data as for preceding; SBA, SB.003139 to SB.003147 • 1 ♀; same data as for preceding; ZFMK, ZFMK-TIS-8011500 . – Samtskhe-Javakheti • 1 ♂; Kodiani ; 41.7300° N, 43.3485° E; 2080 m a.s.l.; 10 May 2023; W. Opdekamp leg.; WOR, A021 .

Description

Male

LENGTH. Body 6.5–8.5 mm, wing 5.5–7 mm.

HEAD. Face bare, black, shiny, with facial tubercle, pruinose below lunule, with facial tubercle, gena with small pruinose area. Parafacia black, shiny or slightly pruinose, white pilose, wide, about 3/4 as wide as postpedicel. Frontal triangle black, shiny, very narrowly pruinose along eye margin, with long black pile. Length of eye contiguity about as long as length of frons. Angle of approximation of eyes ca 80–90°. Vertical triangle black, shiny, ocellar triangle shiny, long black pilose. Occiput pruinose, shiny on dorsal part, short yellow and long black pilose. Lunule dark orange to black, with distinct medial arm, separating acetabula. Scape black, anteriorly with black setae; pedicel black, anteriorly with black setae; postpedicel black, rounded, pruinose, about as wide as high; arista short, black, bare, basal one third thickened. Eye with long black pile.

THORAX. Scutum black, shiny, finely punctured, with long erect black pile, some variable yellow pile intermixed. Scutellum shiny, with erect long and short black pile, sometimes some variable yellow pile intermixed, posterior margin with black setae. Pleura black, slightly pruinose, with black pile, pile on proepisternum and metasternum white, pile intermixed white and black on katepisternum; dorsal and ventral pile patches on katepisternum widely separated. Haltere pedicellum dark yellow, capitulum black.

WING. Wing hyaline, entirely microtrichose, veins dark brown to black.

LEGS. Legs black. Coxae pruinose, with mixed yellow and black pile. Trochanters with mixed black and yellow pile. Profemur with black pile except a few yellow pile anterolaterally; mesofemur with black pile, basis antero- and posterolaterally with mixed black and yellow pile; metafemur black pilose; posterolaterally with mixed black and yellow pile; anterolaterally at basis with some yellow pile; ventrally with short black setae. Protibia black pilose, anterolateral yellow pilose; mesotibia black pilose; metatibia black pilose, apical half of anterolateral side yellow pilose. Protarsus dorsally and posterolaterally black pilose, ventrally and anterolaterally yellow pilose; mesotarsus black pilose; metatarsus dorsally black pilose, ventrally yellow pilose.

ABDOMEN. Terga I–III shiny, medially slightly pruinose; tergum IV shiny; terga I–IV laterally with long white pile except with black pile along tergum II and often black pile at posterolateral corners of terga I, III and IV, medially with adpressed black or mixed black and yellow pile. Sternum I pruinose, shiny in center; sterna II–III shiny; sternum IV shiny, posterior margin broadly slightly pruinose; sternum I with erect white pile, sternum II with long erect yellow pile, sometimes with a little black pile medially; sternum III–IV with adpressed mixed black and yellow pile. Genitalia with surstylus about 1.6 times as long as wide, on apical part with field of microtrichia ( Fig. 30D). Ventral lobe of postgonite longer than dorsal lobe ( Fig. 30C). Apical sclerite of aedeagus with wide and large anterior lobes, lacking posterior lobes.

Female

LENGTH. Body 5.5–7 mm, wing 5–6 mm.

Similar to the male, except for normal sexual dimorphism and the following characters. Frons with mixed yellow and black pile. Scutum with long mixed black and yellow pile, yellow pile often dominating. Terga shinier, with larger proportion of white pile, laterally more often with exclusively white pile.

Genetics

Our NJ tree has a cluster (BS<90%) with all the DNA barcodes of C. melanura , C. bracusi , C. triamilia , C. gemmula sp. nov., C. vernalis and C. confusa sp. nov., which shows relatively low interspecific p-distance (maximum p-distance among all the cited species <0.022), except for the specimen of C. vernalis ZFMK-DIP-00093901 (= ZFMK-TIS-8014645) that reaches interspecific p-distances of 0.0285 (see Supp. file 3: Table S2). All DNA sequences of C. gemmula cluster together.

Biology

Alpine zone species collected between 2080 and 3000 m a.s.l. in open, rocky areas. Flying low, visiting low flowers or sitting on rocks. A group of males has been observed sitting on an elevated part of an exposed road verge, performing swift short flights and returning to the same spot.

Distribution

Only known from the type localities in the Greater and Lesser Caucasus in Georgia.