Cheilosia ( Cheilosia ) ushguliensis, 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 : 140-144

Cheilosia ( Cheilosia) ushguliensis sp. nov.

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Figs 72–73

Differential diagnosis

Cheilosia ushguliensis sp. nov. is a member of a group of closely related species, called the proxima group ( Vujić et al. 2013) in which the pilose eyes, posterior margin of scutellum with setae, usually partly yellow legs, continuously pilose katepisternum, pruinose sterna and the shape of postgonite are distinctive characters. For a full diagnosis of the Cheilosia proxima group see Vujić et al. (2013). Within the proxima group, C. ushguliensis is very similar to C. balkana Vujić, 1994 (known from the Alps and the Balkan Peninsula) and males of our new species key out to those of C. balkana when using the identification key by Vujić et al. (2013). Male of C. ushguliensis differs from the male of C. balkana as follows: facial tubercle narrower and less differentiated ( Fig. 73A), frons slightly pruinose instead of densely pruinose, ocellar triangle partly or predominantly with yellow pile ( Fig. 73A) (with black pile in C. balkana ), with higher proportion of black pile on scutum, without field of short pile on posterior part of scutum, haltere capitulum dark brown to black (yellowish in C. balkana ), tibiae distinctly yellow at both ends ( Fig. 72A) (tibiae all black except knees in C. balkana ), and tergum III largely and tergum IV partly pruinose (both terga completely shiny in C. balkana except for the anterior margin of tergum III). In rare cases, males of C. gigantea and C. proxima can have the abdomen with (almost) entirely yellow pile like males of C. ushguliensis , but those of C. gigantea and C. proxima have the facial tubercle more developed, more protruding ( Fig. 31B vs 73A). Moreover, C. gigantea is on average larger ( 8–12 mm vs 8–10 mm) and has the metafemur with anteroventral pile fringe longer than the anterodorsal pile fringe; on the other hand, C. proxima has the dorsal lobe of postgonite with a more or less distinct hook on its dorsal margin, which is absent in C. ushguliensis ( Fig. 73C). Both male and female can be mistaken for C. velutina given the poorly developed facial tubercle, but facial tubercle still better developed than in C. velutina and they have the postpedicel black (basoventrally orange in C. velutina ). In addition, the male terga I–IV have yellow pile, rarely posterior margin of tergum IV with a few black pile (in C. velutina terga II–III medially with field of black pile just anterior to posterior margin). In the key by Vujić et al. (2013), females of C. ushguliensis key out near C. proxima and C. gigantea and not C. balkana , as the tibiae are yellowish at both ends. Females of our new species differ from females of C. proxima and C. gigantea by shiny terga III–IV (at most some pruinosity at anterior margin of tergum III) (in C. proxima and C. gigantea the central part of tergum III and the anterior part of tergum IV are pruinose) and scutum with erect golden pile ( Fig. 72C) (in C. proxima and C. gigantea scutal pile are often partly black and semi-adpressed). Furthermore, female of C. ushguliensis differs from the female of C. balkana as follows: facial tubercle less differentiated ( Fig. 73B), scutum entirely with yellow pile ( Fig. 72C) (with partly black pile in C. balkana ), and tibiae yellowish at both ends ( Fig. 72C) (tibiae only yellow at base in C. balkana ).

Etymology

The species name is derived from the locality where we collected most of the type series, the Georgian village of Ushguli in the Greater Caucasus and the Latin suffix ‘- ensis ’ denoting place, locality, country, or belonging to, pertaining to ( Brown 1956: 45, 303). Species epithet is to be treated as an adjective.

Material examined

Holotype

GEORGIA • ♂; Samegrelo-Zemo Svaneti, near Ushguli, close to river Inguri ; 42.9498° N, 43.0718° E; 2270 m a.s.l.; 15 Jun 2019; X. Mengual leg.; ZFMK, ZFMK-TIS-8008812 = ZFMK-DIP-00066503 .

Paratypes

GEORGIA – Racha-Lechkhumi and Kvemo Svaneti • 1 ♂; Tsana ; 42.915° N, 43.143° E; 1969 m a.s.l.; 19 Jun. 2019; S. Bot leg.; SBA, SB.002344 • 1 ♂; same data as for preceding; L. Hofstee leg.; LHH • 1 ♂; near Tsana ; 42.9090° N, 43.1425° E; 1900 m a.s.l.; 19 Jun. 2019; F. Van de Meutter leg.; FMT • 1 ♀: near Tsana ; 42.9160° N, 43.1428° E; 1975 m a.s.l.; 19 Jun. 2019; X. Mengual leg.; ZFMK, ZFMK-TIS-8008815 = ZFMK-DIP-00066509 . – Samegrelo-Zemo Svaneti • 1 ♂; Ushguli ; 42.948° N, 43.070° E; 2258 m a.s.l.; 15 Jun. 2019; S. Bot leg.; SBA, SB.003242 • 1 ♀; same data as for preceding; SBA, SB.003243 • 1 ♂; Ushguli ; 42.909° N, 43.007° E; 2294 m a.s.l.; 16 Jun. 2019; S. Bot leg.; SBA, SB.002340 • 2 ♂♂; Ushguli ; 42.9062° N, 42.9370° E; 2615 m a.s.l.; 16 Jun. 2019; F. Van de Meutter leg.; FMT, ZFMK-TIS-8010392 • 1 ♂; Ushguli ; 42.9062° N, 42.9370° E; 2615 m a.s.l.; 16 Jun. 2019; X. Mengual leg.; ZFMK, ZFMK-TIS-8008811 = ZFMK-DIP-00066502 • 1 ♂; Ushguli ; 42.56° N, 43.04° E; 2260 m a.s.l.; 16 Jun. 2019; J. van Steenis leg.; JSB, 2019-01.141 • 1 ♂; near Ushguli ; 42.9140° N, 43.0911° E; 2575 m a.s.l.; 18 Jun. 2019; X. Mengual leg.; ZFMK, ZFMK-TIS-8010389 = ZFMK-DIP-00066501 • 2 ♀♀; near Ushguli ; 42.9140° N, 43.0911° E; 2575 m a.s.l.; 18 Jun. 2019; X. Mengual leg.; ZFMK, ZFMK-TIS-8009222 = ZFMK-DIP-00066607 , ZFMK-TIS-8009223 = ZFMKDIP-00066608 • 1 ♂; Ushguli ; 42.914° N, 43.090° E; 2562 m a.s.l.; 20 Jun. 2019; S. Bot leg.; SBA, SB.003241 = ZFMK-TIS-8010393 • 2 ♀♀; same data as for preceding; SBA, SB.003245 , SB.003246 • 1 ♂; near Ushguli ; 42.9140° N, 43.0911° E; 2575 m a.s.l.; 20 Jun. 2019; F. Van de Meutter leg.; FMT, ZFMK-TIS-8010391 • 1 ♀; same data as for preceding; FMT • 1 ♂; near Ushguli ; 42.9142° N, 43.0900° E; 2564 m a.s.l.; 20 Jun. 2019; J.H. Skevington leg.; CNC, CNC1388145 • 1 ♀; same data as for preceding; CNC, CNC1388110 • 1 ♂; Shkhara glacier; 42.9616° N, 43.0914° E; 2447 m a.s.l.; 12 Jul. 2021; S. Bot leg.; SBA, SB.003247 .

Description

Male

LENGTH. Body 8–10 mm, wing 6.5–8 mm.

HEAD. Face black, slightly pruinose, more densely pruinose below lunule, bare, with moderately pronounced facial tubercle, facial tubercle and mala anteriorly poorly differentiated. Parafacia black, equal in size to half the width of the postpedicel, weakly pruinose, white pilose. Frons including lunule black, slightly pruinose, with long black pile. Length of eye contiguity about 1.2 times the length of frons. Angle of approximation of eyes ca 90°. Ocellar triangle and occiput pruinose, with long mainly yellow pile, ocelli arranged in an isosceles triangle or with longest side along occiput. Lunule dark orange to blackish, with distinct medial arm, separating acetabula. Scape, pedicel and postpedicel black; postpedicel squarish, about as wide as high; arista black, very short pilose, maximum width of pilosity less than half the maximum width of the arista. Eye with yellow pile, length of pile equal to length of pedicel.

THORAX. Scutum black, with dark-olive shine except narrowly anteriorly and notopleuron slightly pruinose, finely punctured, with long erect yellow and black pile of one length, proportion variable, but yellow pile dominating, pile not mixed but black pile restricted to the sides, central part of the scutum always with yellow pile. Scutellum black, shiny, with yellow pile, posterior margin with multiple long black setae, with a slight transverse depression one quarter from apex. Pleura black, pruinose, with yellow pile, posterior anepisternum and anepimeron with mainly yellow pile, sometimes some black pile intermixed; katepisternum continuously pilose. Haltere pedicellum yellow, capitulum dark brown to black.

WING. Wing including alula entirely microtrichose, veins dark brown, stigma yellow, vein M 1 meeting vein R 4+5 at a straight angle.

LEGS. Coxae, trochanters, femora, tibiae and tarsi black except yellow apex of femora and basal 1/3–1/4 and apical 1/5–1/6 of tibiae; pile on legs predominately yellow mixed with black; basal 2/3 of metafemur with the anterodorsal pile as long as anteroventral pile.

ABDOMEN. Terga I–IV with long, fine, erect yellow pile, rarely posterior margin of tergum IV with a few black pile; tergum I pruinose; terga II–III laterally shiny, medially pruinose, tergum IV pruinose on anterior half to quarter. Sterna I–IV thickly and completely pruinose, with erect yellow pile, adpressed medially on sterna III–IV. Hypopygium pruinose, with yellow pile. Genitalia with surstylus ca 1.4 times as long as wide; dorsal lobe of postgonite narrow basally, long and pointed without a clear hook near the top.

Female

LENGTH. Body 8.7–9 mm, wing 7.2–7.5 mm.

Similar to the male, except for normal sexual dimorphism and the following characters. Frons with yellow pile except a few black pile around ocellar triangle. Postpedicel rarely basally reddish. Pile on scutum and pleura golden yellow, rarely a few black pile on posterior anepisternum, post-alar calli and near wing base. Terga with erect yellow pile at the sides, adpressed in the middle. Tergum I pruinose. Tergum II laterally shiny, medially pruinose, terga III–IV shiny, except for a small area along the anterior margin of tergum III, which is pruinose.

Genetics

All DNA sequences of C. ushguliensis sp. nov. group together in our NJ tree with high support (BS = 99.4%).

Biology

Collected between 1900–2615 m a.s.l. on extensive grasslands and in lush vegetation along roadsides.

Distribution

Only known from the Greater Caucasus in Georgia.