Brachysomus (Brachysomus) subnudus ( Seidlitz, 1868 )

Yunakov, Nikolai, 2022, A review of the genus Brachysomus Schoenherr (Coleoptera: Curculionidae: Entiminae), Zootaxa 5193 (1), pp. 1-165 : 30-31

Brachysomus (Brachysomus) subnudus ( Seidlitz, 1868)

Figs. 25, 26 , 75, 76 , 142, 143 , 186 , 238A

Platytarsus subnudus Seidlitz, 1868: 88 . Type locality: ‘Austria’; Dalla Torre et al. 1937: 175; Smreczyński 1966: 86; Dieckmann 1980: 258 (fig. 109 on page 256); Košťál 1991a: 104.

Redescription. Measurements: Body length 2.00–2.55 mm, width 1.05–1.55 mm. Vestiture: Body sparsely covered with small slender grey scales. Sides of pronotum covered with dense but not serried lanceolate scales. Setae strongly erect, short, weakly spatulate, obtuse (0.3x–0.5x as long as width of interstiae), evenly covering head and pronotum. Elytral interstiae with 1–3 rows of erect setae. Antennae and ventrites setose and covered with very thin, recumbent hairs. Colouration: Integument of body brown, antennae and legs yellowish-brown. Vestiture uniformly pale, scales without pearly shine.

Head: Rostrum weakly transverse [RL/RW = 0.86–0.93 (0.89)], sharply narrowed from base to middle, with lateral margins in line with lateral margins of temples. Antennal sockets distinctly visible in dorsal view. Pterygia not projecting from outline of rostrum. Antennal scrobes sharply developed, deep, directed to ventral margin of eye, reaching ventral side of rostrum. Epistome weakly delimited by thin U-shaped carina. Epifrons nearly parallel-sided, flat, in male with distinct median longitudinal sulcus, not carinate, separated from vertex by shallow transverse depression. Vertex flat. Eyes oval, strongly convex, highest at middle [VW/ELD = 1.8–2.0 (1.9)]. Antennae: Scape gently curved, evenly widened to apex; funicular antennomeres: 1st [L/W = 1.4–1.6] and 2nd [L/W in males 1.25; in females 1.67] elongate, 3rd–7th in males transverse [L/W = 0.6–0.75]; 3rd–5th as long as wide, 6th–7th transverse [L/W = 0.5–0.6]; club egg-shaped.

Thorax: Pronotum transverse [PL/PW = 0.69–0.71 (0.70)], widest at middle, evenly convex at disc and sides, evenly constricted anteriorly and posteriorly, densely finely punctate. Elytra: in female oval, strongly convex at disc, in male oblong-oval [EL/EW = 1.27–1.39 (1.33)], weakly convex at disc. Elytral interstiae weakly convex, shiny, 2x wider than striae. Punctures broadly separated, spaces between punctures very weakly concave, somewhat narrower than diameter of puncture. Legs: Tibiae in both sexes with distinct mucro. Fore tibiae straight, with apical external angle not protruding. Second tarsomere weakly transverse. Fifth fore tarsomere extending beyond apical lobes of 3rd by length of the lobes.

Abdomen: First ventrite with posterior margin weakly sinuate. Male 5th ventrite transversally convex, apical margin truncate, with bilateral bunches of pale hairs. Female 5th ventrite flat, with apical margin widely rounded. Male genitalia: Aedeagus heavily sclerotized through entire length; median lobe 0.7x as long as apodemes, evenly narrowed apically. Apex attenuate narrowly rounded, not dentate (in lateral view). Endophallus evenly covered with spicules, with small, bifurcate endophallic sclerite. Ventral membranes rounded, membranous. Parameres free, well developed, as long as width of tegmenal ring. Posterior margin of basal piece sinuate. Spermatheca: Collum and ramus connate, collum 2x longer than ramus, ramus varies in shape.

Diagnosis. This species is very similar to B. dispar , differing by the following characters: aedeagus at apex without tooth; epifrons narrowed from base to middle and parallel-sided from middle to apex, in male with distinct median longitudinal sulcus; setae at elytral interstriae broader than scales; male 5th ventrite without depression at apex, with sparse, light, thin hairs; hind tibiae in male distinctly mucronate and internal side of fore tibiae in male weakly S-shaped.

Distribution. France (Jura Mountain Range), Austria (Tirol, Niederösterreich, Burgenland), Germany (Bayern), Hungary, Slovakia, Czechia (Moravia), Poland (Silesia).

Bionomics. This species inhabits leaf litter in bushy steppes and xerothermic oak forests ( Quercus pubescens ) ( Smreczyński, 1966; Benedikt, 2001). Adults are present from April to September ( Dieckmann, 1980; Košťál, 1991a).

Type material. Lectotype ♂ (ZSM), designation: Košťál, 1991a.

Additional material examined. AUSTRIA: 4♀, ‘Wöllersdorf, Austria inf.’ (NMPC); 1♂, ‘Tirolia [= Tirol, a historic area corresponding to modern mountain disticts in Austria—Nordtirol, and Italy—Trentino-Südtirol, Osttirol,]’ (NMPC); 2♀, ‘Wien, Kirsch’ (MTD); 1♂, 2♀, ‘Wien, Reitter’ (HNHM); 3♂, 4♀, ‘Vöslau [= Bad Vöslau, Niederösterreich], 15.v.1936’ (HNHM); 1♀, ‘Umgegend von Mödling [Niederösterreich], Reitter’ (ZMUH); 2♀, ‘Styria, Tobibad’ (FJc). CZECHIA: 2♂, 1♀, ‘Mähren, Hrotovice’ (MTD). FRANCE: 3♂, 1♀, ‘Gallia, Märkel’ (ZMUN); 1♂, ‘Wellheim, Fränk. Jura, K. Ruile’ (MTD). GERMANY: 3♂, 2♀, ‘Ruhrbah bei Neuburg an der Donau, Karl Ruile’ (MTD, ZMUH). HUNGARY: 3♂, 9♀, Kőszegi hgs., 20–22.v.1936, Kaszab leg.; 1♂, ‘Kőszegi hgs., Bozsok, 29.vi.1980, A. Podlussány’ (HNHM); 1♀, Kőszegi hgs., Szabóhegy, 29.vi.1980, A. Podlussány leg. (HNHM); 1♂, 1♀, ‘Hungaria, Kirsch’ (MTD); 1♂, ‘Ungarn, Neusiedler S.’ (MTD); 1♀, ‘Ungaria, Neutraer Comitat, H. Raffesberg’ (MTD). SLOVAKIA: 1♀, Vlára, 29.vii.1935, O. Kodym leg. (NMPC);1♀, ‘Trenčín, iii.1936, Roubal’ (HNHM); 1♀, ‘Zlatovce, Trenčín’ (NMPC); 1♂, 3♀, ‘Motešice, 7.vii.1932 Roubal leg.’ (NMPC); 1♂, ‘Inoves, Roubal leg.’ (NMPC).

Figures

FIGURE 186. Brachysomus subnudus: A: aedeagus, dorsal and lateral view; B: tegmen; C: spermatheca; D: scales of elytra; E: sternite VII; F: tergite VIII.

FIGURE 238. Occurrence map of Brachysomus s. str.

FIGURES 25–30. Brachysomus, dorsal habitus: 25: B. subnudus, male. 26: B. subnudus, female. 27: B. frivaldszkyi, male. 28: B. frivaldszkyi, female. 29: B. lituratus, male. 30: B. lituratus, female.

FIGURES 71–78. Brachysomus, details: 71, 72: B. styriacus. 73, 74: B. frivaldszkyi. 75, 76: B. subnudus. 77, 78: B. dispar.

FIGURES 142–147. Brachysomus, dorsal habitus: 142: B. subnudus, male. 143: idem, female. 144: B. slovacicus, male 145: B. rokosensis, male. 146: B. hispidus, male. 147: B. hispidus, female.