Brachysomus (Hippomias) alexeevi Yunakov, 2006

Yunakov, Nikolai, 2022, A review of the genus Brachysomus Schoenherr (Coleoptera: Curculionidae: Entiminae), Zootaxa 5193 (1), pp. 1-165 : 68

Brachysomus (Hippomias) alexeevi Yunakov, 2006

Figs. 130 , 223 , 240A

Brachysomus alexeevi Yunakov, 2006: 310 . Type locality: Russia, North Ossetia, Zmeiskiye Mts.

Redescription. Measurements: Body length 1.7–1.95 mm, width 1.0–1.15 mm (in holotype 1.95 and 1.15 mm). Vestiture: Body thin, evenly covered with light, fine, small, piliform and lanceolate scales, and short, erect, slightly widened, blunted apically setae. Setae as long as 2/3 interstrial width. Colouration: Body brown, antennae and legs yellow-brown.

Head: Rostrum parallel-sided, as long as wide. Pterygia clearly visible in dorsal view, almost not projecting from outline of rostrum. Epifrons moderately widened apically, weakly convex longitudinally, separated from vertex by weak transverse depression, with broad, shallow, median longitudinal sulcus, width near antennal insertion 1.5x less than vertex. Eyes small (VW/ELD =2.20–2.25), round, strongly convex, situated almost at level of vertex. Vertex weakly convex. Antennae: Scape weakly evenly curved and widened distally, at apex 1.6x as wide as at base; funicular antennomeres: 1st and 2nd elongate, 1st (L/W = 1.25) thicker than 2nd; 3rd–7th transverse; club broadspindle-shaped, weakly separated from funicle.

Thorax: Pronotum slightly transverse (PL/PW = 0.77–0.80), evenly convex at sides, widest at middle. Disc evenly convex longitudinally, finely densely granulate. Elytra: broad-oval (EL/EW =1.17–1.23), in female broadoval, evenly convex at disc and sides. Striae linear. Punctures deep, slightly separated; spaces between punctures somewhat narrower than diameter of puncture, situated deeper than level of interstriae. Interstriae flat, shiny, 1.3x as wide as striae. Legs: Femora moderately swollen in middle part. Tibiae thin, strongly elongate. Fore tibiae with straight external margin, external apical angle weakly projecting from contour of fore tibia. First tarsomere triangular, 2nd strongly transverse. Fifth fore tarsomere extending beyond apical lobes of 3rd by 0.60 length of the lobes.

Abdomen: Male 5th ventrite without posterior depression, posterior margin broadly rounded. Male genitalia: Median lobe weakly sclerotized, 3.2x shorter than apodemes, parallel sided, strongly narrowed and acute apically; endophallus with small endophallic sclerite, bearing armed fields of two spiculae types: proximal field consists of needle-shaped, oblong, acute spiculae, distal field comprises sparse, microscopic, tubercle-shaped sclerites; tegmenal ring with well-developed and divided parameres. Spermatheca with short collum and ramus, corpus distinctly swollen.

Diagnosis. Brachysomus alexeevi is closely related to B. sulcatus , differing by shorter erect setae (as long as 2/3 interstrial width; in B. sulcatus striae nearly as long as interstrial width), shape and size of scales on the elytra (in B. sulcatus pilose scales rather long, their shape uniform), evenly curved antennal scape and structure of the aedeagus.

Distribution. Central Caucasus (Kabardino-Sunzhensky Mt. Range: Zmeiskiye Mts.).

Bionomics. This very rare species is known from two specimens from leaf- and grass litter in deciduous forest and meadows of the lower mountain zone, at around 500 m a.s.l.

Type material. RUSSIA, North Ossetia: Holotype ♀ (ZIN), Central Caucasus, North Ossetia, Kabardino- Sunzhensky Mt. Range, Zmeiskiye Mts., 6 km NW of mouth of Dur-Dur River. [N43.281563, E44.167528], N slope, 540 m, Fagus forest, Rubus-Arum association, 18.viii.1986, S. K. Alexeev leg.. Paratype ♂ (ZIN), Central Caucasus, North Ossetia, Kabardino-Sunzhensky Mt. Range, Zmeiskiye Mts., 3.5 km NW of Kardzhin [N43.291894, E44.256847], ESE slope, 500 m, steppe meadow with Amigdalus nana L. S. K. Alexeev leg.

Figures

FIGURE 223. Brachysomus alexeevi: A: body; B: scales of elytra; C: aedeagus; D: tegmen; E: spermatheca.

FIGURE 240. Occurrence map of Brachysomus subgenus Hippomias.

FIGURES 124–130. Brachysomus, details: 124: B. albanicus, head dorsal view. 125: B. albanicus, head lateral view 126: B. simulans head dorsal view. 127: B. simulans, head lateral view. 128: B. rhinomioides, head dorsal view. 129: B. rhinomioides, head lateral view.