Geodromicus Redtenbacher, 1857

Shavrin, Alexey V., 2024, Review of the brevicollis group of the genus Geodromicus Redtenbacher, 1857 (Coleoptera: Staphylinidae: Omaliinae: Anthophagini), Zootaxa 5468 (3), pp. 581-599 : 582-583

Genus Geodromicus Redtenbacher, 1857

(type species: Staphylinus plagiatus Fabricius, 1798 )

Geodromicus Redtenbacher, 1857: 244 (replacement name for Geodromus Heer )

Geobius Heer, 1839: 193

Geodromus Heer, 1841: 572

Psephidonus Gistel, 1856: 29

Brachydromicus A. Bordoni, 1993 syn. n.

Redefenition of the brevicollis group

Diagnosis. Smallest species of the genus (3.05–5.35 mm), with relatively small transverse pronotum, from widest anterior portion slightly or strongly narrowed posteriad; elytra short, slightly broader than long, slightly or strongly narrowed posteriad, distinctly less than twice shorter than pronotum; aedeagus short, median lobe wide with broadened or narrow preapical part, elevated parameral surface and sclerotized elongate lateral edges from each side of this elevation; internal sac narrow and moderately short, with moderately short narrow flagellum and elongate sclerotized structures in basal portion.

Species included. Geodromicus alborzensis sp. n., G. brevicollis Fauvel, 1875 , G. transversus Motschulsky, 1860 .

Distribution. Species of the brevicollis group are distributed in the western part of the Palaearctic Region and known from the Caucasus, eastern Turkey and Iran.

Bionomics. The species of the brevicollis group inhabit banks of rivers and streams of mountains, and can be found in gravel, under stones, etc. These species can be found in the subnival zone along snow fields. Specimens were collected at elevations from 1300 to 3700 m a.s.l. from April to September, with the largest number of specimens observed in August.

Remarks. The brevicollis group was erected by Bordoni (1984) for three Caucasian species: G. brevicollis , G. latiusculus Eppelsheim, 1878 and G. constricticollis Eppelsheim, 1890 . Besides that, A. Bordoni described the subgenus Brachydromicus Bordoni, 1984 , without designation of a type species (nomen nudum). All three species listed above were attributed to this subgenus based on similar morphology of the shortened aedeagus. During the study of the material, I could not find external morphological features that would prove the need for erection of a separate subgenus within Geodromicus . Based both external and internal morphology, all these species are not significantly different from other species of the genus. Thus, I synonymized Brachydromicus with Geodromicus . Based on the general structure of the aedeagus with elevated parameral surface and sclerotized elongate lateral edges from each side of this elevation and the presence of a short flagellum between sclerotized structures in the basal portion, the brevicollis group is similar to the longipes and the major groups ( Bordoni 1984). From both these groups it can be distinguished by the smaller body, less sclerotized lateral edges in the middle of the median lobe and narrower apical portions of the parameres. Species of the brevicollis group are quite variable in the proportions of the forebody and features of the sculpture, and can be reliably distinguished based on the morphology of the aedeagus.

Key to species of the brevicollis group

1 Lateral margins in front of posterior angles of pronotum short and distinctly concave. Median lobe very wide ( Figs. 18, 20–22 ). Habitus as in Fig. 6 . Body length: 3.05–5.30 mm. Body brown to reddish-brown. Caucasus............... G. transversus

- Lateral margins in front of postrerior angles of pronotum elongate and subparallel, sometimes slightly concave. Median lobe wide, distinctly narrower in preapical part. Body reddish-brown................................................ 2

2 Elytra slightly less than twice as long as pronotum. Ocelli indistinct. Preapical part of median lobe wide ( Fig. 16 ). Habitus as in Fig. 5 . Body length: 3.90–5.10 mm. Iran (Elburz Mts.)....................................... G. alborzensis sp. n.

- Elytra about one and a half times as long as pronotum. Ocelli small, but well distinct. Preapical part of median lobe moderately narrow ( Figs. 7, 9–14 ). Habitus as in Figs. 1–4 . Body length: 3.32–5.35 mm. Caucasus, NE Turkey, NW Iran.. G. brevicollis

Figures

FIGURES 16–23. Aedeagus of Geodromicus alborzensis (Figs. 16–17: holotype) and G. transversus (Figs. 18–19: Russia, Krasnaya Polyana; Fig. 20: lectotype of G. transversus; Fig. 21: lectotype of G. flavipes; Fig. 22–23: Karachay-Cherkessia, Epchik Pass): 16, 18–22—parameral view, 17, 19—lateral view, 23—internal sac. Scale bars: 0.1 mm.

FIGURES 1–6. Habitus of Geodromicus: 1—G. brevicollis (Russia: Karachay-Cherkessia), 2—G. brevicollis (Turkey: Ardahan), 3—G. jarrigeanus (holotype), 4—G. ziganensis (holotype), 5—G. alborzensis (holotype), 6—G. transversus (Russia: Karachay-Cherkessia). Scale bar: 1.0 mm.

FIGURES 7–14. Aedeagus of Geodromicusbrevicollis (Figs.7–8:North Ossetia-Alania, basin ofArdon River; Fig. 9: Karachay- Cherkessia, Dukka River; Fig. 10: holotype of G. jarrigeanus; Fig. 11: Armenia, Gavar; Fig. 12: holotype of G. ziganensis; Fig. 13: Turkey, Ispir-Ovitgeç; Fig. 14: Turkey, Sevsat): 7, 9–14—parameral view, 8—lateral view. Scale bars: 0.1 mm.