Brachysomus (Brachysomus) lituratus ( Reitter, 1884 ) Yunakov, 2022

Yunakov, Nikolai, 2022, A review of the genus Brachysomus Schoenherr (Coleoptera: Curculionidae: Entiminae), Zootaxa 5193 (1), pp. 1-165 : 29-30

Brachysomus (Brachysomus) lituratus ( Reitter, 1884) comb. n.

Figs. 29, 30 , 85, 86 , 185E–I , 237

Platytarsus (Foucartia) lituratus Reitter in Stierlin, 1884: 91. Type locality: ‘Türkei’; Solari 1948: 27 (as Parafoucartia ); Smreczyński 1966: 87 (as Foucartia ); Dieckmann 1980: 262 (as Foucartia ); Borovec & Pelletier 2010: 16 (as Foucartia )

Redescription. Measurements: Body length 2.10–2.95 mm, width 1.25–1.80 mm. Vestiture: Body, head, and legs (except tarsi) densely covered with round overlapping scales. Setae spatulate, 0.3x as long as width of elytral interstria, evenly covering head and pronotum. Elytral interstiae with 1–3 rows of setae. Antennae and tarsi setose and finely pilose. Colouration: Body dark-brown, appendages yellowish-brown. Scales grey to yellowish-grey, with slight pearly shine; disc of pronotum and elytra occasionally with confused brown spotted pattern.

Head: Rostrum as long as wide, parallel-sided, sharply separated from head capsule. Pterygia not projecting from outline of rostrum. Antennal scrobes sharply developed and deep, directed to ventral margin of eye, reaching ventral side of rostrum.Epistome flat, delimited by V-shaped thin carina. Epifrons narrowed from base to midlength, parallelsided from midlength to apex; epifrons roughly punctate, flat, not separated from vertex by transverse depression. Vertex flat, 1.4x wider than epifrons at the level of antennal insertion, finely striate and longitudinally punctate. Occiput weakly constricted ( Figs. 85, 86 ). Eyes broadly-oval, strongly convex, highest posteriorly [VW/ELD = 2.19–2.53 (2.36)]. Antennae: Scape almost straight, strongly widened along distal 1/3; funicular antennomeres: 1st elongate, 1.75–1.80x longer than wide, 2nd 1.50–1.66x, 3rd 1.00–1,33x longer than wide, 4–6th as long as wide, 7th 0.8x as long as wide; club spindle-shaped.

Thorax: Pronotum transverse [PL/PW = 0.62], widest posteriad of mid length, evenly convex at disc and sides, weakly constricted anteriorly, densely finely punctate. Elytra: broadly-oval [EL/EW = 1.65–1.69 (1.67)], strongly convex at disc and sides. Elytral interstiae distinctly convex, shiny, 2.5x wider than striae. Punctures broadly 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 without mucro. Second tarsomere transverse. Fifth tarsomere extending beyond apical lobes of 3rd by 0.75x length of the lobes.

Abdomen: First ventrite with posterior margin weakly sinuate. Male 5th ventrite weakly convex, with straight posterior margin; 5th ventrite of female slightly convex, with posterior margin widely rounded. Male genitalia: Aedeagus heavily sclerotized at apex, ventral wall membranous. Median lobe 0.5x as long as apodemes. Apex rounded, not dentate (in lateral view). Endophallus evenly covered with microscopic spicules; endophallic sclerite very small, bifurcate. Ventral membranes rounded, membranous. Parameres well developed, free, as long as width of tegminal ring; posterior margin of basal piece weakly sinuate. Spermatheca: ramus and collum separated by narrow gap, ramus as long and slightly narrower than collum.

Diagnosis. Brachysomus lituratus was previously considered as part of the genus Foucartia due to the metallic shine of its scales and the presence of a constriction on the occiput. On the other hand this species differs from other members of the genus Foucartia by the epistome not delimited from the epifrons by a carina and the relatively thick tibiae and antennae. By the structure of the epistomal area and the male genitalia, B. lituratus is very similar to members of the B. hispidus species group, particularly to B. hispidus and B. frivaldszkyi in the structure of the head and the vestiture of the body. From B. hispidus , B. lituratus strongly differs in the elytra rather rounded (broadlyoval to globose; oblong-oval to oval in B. hispidus ), by the presence of a spotted pattern on the elytra and pronotum (lacking in B. hispidus ), the round overlapping scales (not overlapping in B. hispidus ), and the median lobe weakly apically narrowed with broadly rounded apex (in B. hispidus attenuate). From B. frivaldszkyi this species differs by the thick, not widened externally fore tibiae, by the shape of the rostrum (base of rostrum before eyes not convex), spotted pattern on pronotum and elytra, and by the median lobe less acute at apex.

Distribution. Poland, Czechia, Slovakia, Hungary, Ukraine, SW Russia, Turkey. Pontic and Pannonian steppes.

Bionomics. This species inhabits litter in steppes and xerothermic forests.

Remarks. Brachysomus lituratus was described by Edmund Reitter as Platytarsus lituratus in the key published by Gustav Stierlin. Since the number of syntypes is not clear from the original description the designation of lectotype is needed to fix the nomenclature type. The only known syntype is stored in the German Entomological Institute (SDEI) but was apparently overlooked during the revisionary work on Foucartia ; for details see Borovec & Pelletier (2010: 16). This species has been treated in the genus Foucartia (Borovec & Pelletier 2009) due to the presence of metallic scales. Nevertheless, Foucartia liturata agrees with Brachysomus in the vestigial scutellar shield (contrasting the complete scutellar shield in other Foucartia species), the fairly robust articulations of legs and funicular antennomeres, and the complete fusion of the antennomeres of the club (no such fusion in Foucartia cremieri Jacquelin du Val, 1854 and other Foucartia species). In addition, B. lituratus shows close affinity to B. hispidus , B. frivaldszkyi , and B. fremuthi in the poorly developed epistomal carina. Moreover, the male genitalia of B. lituratus is very similar to that of B. frivaldszkyi (see description for details). This leads me to transfer this species as Brachysomus lituratus comb. n. from Foucartia to the B. echinatus species group of Brachysomus , where these three other species are placed. The features of B. lituratus suggest that it is moderately adapted to xerothermic conditions of East-South European steppes, in contrast to B. hispidus and B. frivaldszkyi , which mostly inhabit deciduous forests. A similar adaptation has apparently occurred in B. fremuthi , which is likely most closely related to B. frivaldszkyi .

Type material. TURKEY: Lectotype, ♀ (here designated) (SDEI): “Türkei”, “coll. Stierlin” “LECTOTYPUS / Platytarsus (Foucartia) lituratus Reitter in Stierlin 1884 / Yunakov des. 2022”.

Additional material examined. HUNGARY: 2♀, ‘Hungaria’ (DEI, ZIN); 5♂, 3♀, ‘Isaszeg, Kuthy’ (HNHM); 11♀, ‘Péczel, Kuthy’ (HNHM); 1♀ (HNHM), ‘Nádudvar, Csiki’; 1♀ (HNHM), ‘Tarczal., 9.6.1885’; 2♀, ‘Budapest’ (HNHM); 6♀, ‘Hu. bor. 1955, Bükk hegység; Bélkő teteje vii.12–13 Mihályi leg.’ (HNHM); 1♀, ‘Rákóczifalva, 1935.vi.30’ (HNHM). MOLDOVA: 1♀, Lozova, forest, 22.vi.1989 A. Poiras leg. (ZIN). ROMANIA: 1♀, ‘Marmaros’ (HNHM). RUSSIA: 1♀, Krasnodar Reg., near Novorossiysk, Abrau Dyurso, K.V. Arnoldi leg. (ZIN); 1♂, 1♀, Volgograd Prov., Podtelkovsky Distr., Kumylzhenskaya, 30.vi.1988 E. Komarov leg. (ZIN); 1♂, Rostov Prov., 25 km W of Oblivskaya, 2.vi.1980 Tsherezova leg. (ZIN); 1♂, Kazanskaya, 10.vi.1987, Yu.G. Arzanov leg. (ZIN). UKRAINE: 1♀, Luhansk Prov., Slavianeserbsk, 9.vi.1952, S.I. Medvedev leg. (KUMN); 1♀, near Luhansk, 28.vi.1927, V.I. Talicky leg. (ZIN); 1♀, Donetsk Prov., Bogorodychne, flood-meadow of Severskyi Donets’ Riv., 18.vi.1952 S.I. Medvedev leg. (KUMN); 2♀, Sloviansk Distr., Yarova, 19.v.1939, K. V. Arnoldi (ZIN).

Figures

FIGURE 185. Brachysomus kratkyi: A: aedeagus, dorsal and lateral view; B: tegmen; C: tergite VIII with alical process (frontal wiew); D: spermatheca. Brachysomus lituratus (Reitter, 1884) comb. n.: E: aedeagus, dorsal and lateral view; F: tegmen; G: tergite VIII; H: spermatheca; I: scales of elytra.

FIGURE 237. Occurrence map of Brachysomus lituratus comb. n.

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 79–86. Brachysomus, details: 79, 80: B. rokosensis. 81, 82: B. slovacicus. 83, 84: B. hispidus. 85, 86: B. lituratus.