Brachysomus (Brachysomus) setiger (Gyllenhal, 1840)

Yunakov, Nikolai, 2022, A review of the genus Brachysomus Schoenherr (Coleoptera: Curculionidae: Entiminae), Zootaxa 5193 (1), pp. 1-165 : 44

Brachysomus (Brachysomus) setiger (Gyllenhal, 1840)

Figs. 138, 139 , 154, 155 , 199 , 238B

Platytarsus setiger Gyllenhal in Schoenherr, 1840: 921. Type locality: ‘Austria’; Formánek 1905: 169 ( Brachysomus ); Dalla Torre et al. 1937: 174; Dieckmann 1980: 258; Podlussány 2001: 239; Łętowski et al. 2003: 236.

Barypeithes antoni Reitter, 1895: 204 . Type locality: ‘Central-Ungarn’.

Omias pruinosus Boheman in Schoenherr, 1842: 133. Type locality: ‘Dalmatia’.

Redescription. Measurements: Body length 1.95–3.0 mm, width 1.0–1.7 mm. Vestiture: Body covered with grey, oval scales and slender, obtuse, erect setae, as long as width of elytral interstriae or shorter. Scales in male sparse, recumbent, in female very dense, overlapping, suberect, forming hoar-frost-like cover. Colouration: Body brown to light-brown, legs and antennae yellowish-brown.

Head: Rostrum as long as wide, parallel-sided, sharply separated from head capsule. Antennal sockets distinctly visible in dorsal view. Pterygia not projecting from outline of rostrum. Antennal scrobes sharply developed and deep, directed to ventral margin of eye. Epistome flat, delimited from epifrons by thin V-shaped carina. Epifrons parallel-sided, flat; at level of antennal insertion, 1.3–1.35x wider than vertex, with thin median carina, without median longitudinal sulcus, without transverse depression. Vertex flat, finely striate and longitudinally punctuate. Eyes oval (VW/ELD = 2.3), strongly convex, highest at middle. Antennae: Scape evenly curved, widened distally, thicker in males, at apex 2.3–2.6x wider than at base; funicular antennomeres: 1st and 2nd elongate; 1st larger than 2nd; 3rd–5th as long as wide; 6th and 7th transverse; club egg-shaped.

Thorax: Pronotum transverse, [PL/PW = 0.63–0.65 (0.64)], widest posteriad of mid length, evenly convex at sides, weakly convex at disc, constricted anteriorly and posteriorly, densely, shallowly punctate. Spaces between punctures very narrow, forming reticular sculpture; disc without lateral depressions. Elytra: oval, in female broadoval, strongly convex at disc and sides. Interstriae of elytra weakly convex, 3.5x wider than striae. Punctures well separated. Spaces between punctures very weakly concave, somewhat narrower than diameter of puncture. Legs: Fore tibiae straight, with apical external angle not protruding. Hind tibiae in male with small mucro. 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 with distinct depression, its posterior margin strongly sinuate, with bilateral bunches of long, pale hairs. Male genitalia: Aedeagus heavily sclerotized through entire length. Median lobe as long as apodemes, evenly narrowed apically, strongly, dorsoventrally curved, with ventral surface membranous. Apex flat and acute. Endophallus with fine spicules. Ventral membranes lanceolate, slightly sclerotized. Parameres well developed, fused at base, as long as width of tegmenal ring, posterior margin of basal piece sinuate. Spermatheca: ramus and collum slightly divided at base, ramus and collum equal in length.

Diagnosis. Brachysomus setiger is very similar to B. erinaceus , differing by the shorter erect setae, the denser vestiture of the elytra of the female, the more transverse pronotum (W/L = 1.26–1.30, in B. erinaceus — 1.36–1.52), and the structure of the aedeagus.

Distribution. Central Europe and western part of Eastern Europe.

Bionomics. This species inhabits leaf- and grass litter of bush lands and xerothermic deciduous forests in limestone and gyps. It is a polyphagous species feeding on Quercus , Salvia , Trifolium , Astragalus , Taraxacum , Fragaria, Rosa , Dactylus , Viola , Fraxinus , Achillea , and Abies . Data on biotopes were provided by Dieckmann (1980) in Germany. All host plants were detected by him during laboratory tests at the German Entomological Institute. In Moldova it has been collected on Lathirus pratensis by A. Poiras.

Type material. Lectotype ♂ (here designated) (NHRS): ‘Typus’ (red, printed), ‘Austria Megerle’; glued oncardboard, aedeagus in vial with glycerol and pinned below the beetle. The head is missing.

Additional material examined. CZECHIA: 1 spm. (KJc) Jihomoravsky, Lednice, 25.iv.1999, J. Krátký leg., sifting leaf litter, N48.79972, E16.80333. GERMANY: 6 spm. (KUMN) Saxony-Anhalt, Magdeburg, Reform, DE- 12-14, 1.vi.2012, N. Yunakov leg., Rosa sp. , beating, N52.09444, E11.60389, 40 m. a.s.l., suburban garden; 10 spm. (KUMN) idem, DE-13-02, 14.v.2013, N. Yunakov leg., Rosa sp. , beating, N52.09444, E11.60389, 40 m. a.s.l., suburban garden; 9 spm. (KUMN) Magdeburg env., 3.5 km SE of Beyendorf, Frohser Berge, DE-13-03, 15.v.2013, Yunakov N.N., in grass litter, N52.03494, E11.6619, 115 m a.s.l. MOLDOVA: 4 spm. (ZIN) Transnistria, Vadul Turcului, 8.v.1957, V.I. Talicki leg., N47.93946, E28.994926; 1 spm. (ZIN) Chisinau, Botanical Garden, 24.v.1995, A. Poiras leg., N46.974759, E28.883341. ROMANIA: 2 spm. (KJc) Neamt, Roman env., 4 km SE of Gâdinţi, 3- 4.v.2005, J. Krátký leg., N46.91083, E27.04167, 250 m. a.s.l.; 1 spm. (KJc) Tulcea, Greci env., Muntii Macinului, 6.v.2009, J. Krátký leg., N45.18139, E28.26139, 126 m. a.s.l. UKRAINE: 3 spm. (ZIN) Vinnytsia, Bar, Verkhivka, near Mogilev, 21-26.v.1901, A.K. Chekini leg., N48.90056, E27.64917; 4 spm. (ZIN) idem, 8.vi.1901, Chekini A.K., N48.90056, E27.64917..

Figures

FIGURE 199. Brachysomus setiger: A: body of male; B: scales of elytra of male; C: scales of elytra of male; D: aedeagus; E: spermatheca; F: antenna G: fore tibia of male; H: hind tibia of male; I: scales of elytra.

FIGURE 238. Occurrence map of Brachysomus s. str.

FIGURES 136–141. Brachysomus, main view. 136: B. erinaceus, male. 137: B. erinaceus, female. 138: B. setiger, male. 139: B. setiger, female. 140: B. hegyessyi, male. 141: B. hegyessyi, female.

FIGURES 148–155. Brachysomus, head and pronotum: 148: B. armatus, dorsal view. 149: B. boroveci, dorsal view. 150: B. erinaceus, dorsal view. 151: idem, lateral view. 152: B. hegyessyi. 153: idem, lateral view. 154: B. setiger, dorsal view. 155: idem, lateral view.