Collessomma sibirica, Lukashevich & Blagoderov, 2020

Lukashevich, Elena D. & Blagoderov, Vladimir A., 2020, Review of Mesozoic Perissommatidae (Insecta: Diptera), Zootaxa 4718 (4), pp. 481-496 : 488

Collessomma sibirica sp. nov.

( Figures 2–4 A–C)

urn:lsid:zoobank.org:act:C3983495-DE20-4BDF-B18A-DFD4DC44F617

Holotype. PIN, No. 5340/1681, part and counterpart, well-preserved impression of a male.

Type Horizon and Locality. Khasurty; Western Transbaikalia, Buryatia, Zakamensk District, middle reaches of the River Khasurty, 10 km south of the village of Tsakir (50°21’N 103°37’E); lower part of Gusinoe Ozero Group, Lower Cretaceous.

Etymology. The species epithet refers to Siberia.

Description. Small flies. Thorax dark brown, darker than abdomen and legs. Segments of antenna oval, with length subequal to wide. Sc free, ends proximad of R 1 base; Rs stem subequal to basal segment of R 5. R 4 twice as long as R 3. Legs with strong setae, fifth tarsomere widest. Male ninth tergite wider than long, approximately half the length of gonocoxites. Gonostyli shorter than gonocoxites, widest at midlength and tapering towards apex, with terminal macrosetae.

Measurements (mm). Body length 3.9–4.8 (4.8 holotype), head length/width 0.5/ 0.55 (male?), 0.7/0.8 (holotype, male), antenna length 0.6 (holotype), thorax length 1.1–1.3, abdomen length 2.9, halter 0.7, wing 4.2–4.8 (holotype 4.5).

Material. Besides holotype, paratypes PIN, No. 5026/202± (sex unknown), 5026/206 (male?), 5026/1558± (male?), and PIN, No. 5340/839 (isolated wing).

Figures

FIGURE 2. Male of Collessomma sibirica gen. et sp. nov. A–E. holotype PIN No. 5340/1681. A. Total view. B. Terminalia. C, D. Head, dorsal and ventral view. E.Anterior part of wing with pterostigma. F. PIN No. 5026/1558, head with facets of different size. Scale bars 1 mm (A), 200 μm (B–F).

FIGURE 3. Collessomma sibirica gen. et sp. nov. Paratype PIN No. 5026/206,?male.A. Total view. B. Tarsus. C. Anterior part of wing with pterostigma.Abbreviations: CuA, anterior branch of cubital vein; CuP, posterior branch of cubital vein; im, medial crossvein; M1, M2, M3+4, branches of media; m-cu, media–cubital crossvein; R1, R3, R4, R5, branches of radius; r-m, radial–medial crossvein; Sc, subcostal vein. Scale bars 1 mm (A), 500 μm (C), 100 μm (B).

FIGURE 4. Collessomma gen. nov. A–C. C. sibirica gen. et sp. nov. A, B. Male? PIN No. 5026/206, wing and tarsus. C. Holotype PIN No. 5340/1681, male terminalia. D, E. C. gnoma gen. et sp. nov. Holotype PIN No. 5026/201, wing and male terminalia. F, G. C. mongolica gen. et sp. nov. F. Paratype PIN No. 3559/4154, wing. G. Holotype PIN No. 3559/10039, female terminalia.Abbreviations: aed, aedeagus; cerc, cerci; gst, gonostylus; gx, gonocoxite; TG6–9, tergites 6–9; ST6-8, sternites 6–8. Scale bars 1 mm (A, F), 500 μm (D), 200 μm (C, E, G), 100 μm (B).