Obesoconnus asymmetricus, Jałoszyński, 2023

Jałoszyński, Paweł, 2023, Discovery of Obesoconnus Jałoszyński in the Oriental Region (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 5293 (2), pp. 371-378 : 372-375

Obesoconnus asymmetricus sp. n.

( Figs 1–9 , 14 )

Material studied. Holotype: ♁ THAILAND: two labels: “ FIT(NHP-1): Lum Jangwat / Khao Ang Runai N.P. / [E-THAILAND] / 11-19.x.2005, S. Nomura ” [white, printed], “ OBESOCONNUS / asymmetricus m. / Jałoszyński, 2023 / HOLOTYPUS” [red, printed) ( NSMT].

Diagnosis. Aedeagus strongly asymmetrical, with curved apical projections almost as long as median lobe.

Description. Body of male ( Fig. 1 ) stout and strongly convex, with moderately long appendages, glossy, BL 0.93 mm; pigmentation uniformly dark brown, appendages slightly lighter, vestiture of setae light brown.

Head short, broadest at eyes, HL 0.12 mm, HW 0.24 mm; vertex and frons confluent and weakly convex, posterior portion of frons with minute punctiform impression; supraantennal tubercles small and feebly elevated, but each accentuated by minute impression on its posteromesal margin. Eyes extremely large, oval with narrow posteromedian emargination, coarsely faceted and strongly convex. Punctures on vertex and frons fine, shallow and diffuse, inconspicuous; setae short and sparse, recumbent to suberect. Antennae slender but short, weakly thickened distally, AnL 0.40 mm; scape and pedicel strongly elongate, antennomere III indistinctly transverse, IV–VI each about as long as broad, VII–X each weakly transverse, XI subequal in length to IX–X combined, about 1.6 × as long as broad, indistinctly asymmetrical, with truncate apex.

Pronotum ( Fig. 3 ) nearly semicircular, equally broad between base and middle, PL 0.25 mm, PW 0.30 mm; anterior margin broadly rounded, lateral margins nearly straight and barely discernibly microserrate, posterior margin nearly straight; base with shallow and diffuse transverse groove deepened at each end and with one pair of distinct, deep, elongate lateral impressions; pronotal disc covered with fine but distinct punctures separated by spaces subequal to their diameters, and with sparse, short, suberect setae.

Elytra oval, evenly convex, broadest slightly in front of middle, EL 0.55 mm, EW 0.45 mm, EI 1.22; humeral calli small, elongate, elytral apices separately rounded; punctures smaller and denser than those on pronotal disc, shallow and diffuse; setae sparse, short, suberect.

Legs moderately long and slender, unmodified.

Aedeagus ( Figs 6–9 ) darkly sclerotized, AeL 0.30 mm; stout, strongly asymmetrical, in ventral view suboval with obliquely truncate apex; apical projections composed of three asymmetrical recurved elongate plates, one short and two (adjacent to each other) almost as long as median lobe; endophallic structures with sclerotized slender flagellum; parameres long and slender, asymmetrically bent toward one side of median lobe, exceeding apex of median lobe, each with one long apical seta.

Female. Unknown.

Distribution ( Fig. 14 ). Thailand.

Etymology. The name asymmetricus refers to the remarkably asymmetrical aedeagus.

Remarks. Proportions of body parts (e.g., EI) were included in diagnoses of previously described Neotropical species. However, the addition of two more species demonstrates that the external morphology of Obesoconnus is extremely uniform ( Fig. 14 ), and only the aedeagus offers unambiguous features to identify members of this interesting genus. The aedeagus of O. asymmetricus is oddly shaped and the most complex among nominal species of Obesoconnus , with extremely long and strongly asymmetrical apical projections, not similar to much shorter, or even barely discernible projections in all remaining species. The most unusual feature is the sclerotized flagellum, in the holotype projecting almost entirely from the ostium. In remaining species of Obesoconnus the flagella are not discernible.

The male holotype of O. asymmetricus was collected by a flight intercept trap set at ~ 5 m above the ground on a tree in forest (email from S. Nomura dated 06.04.2023).

Figures

FIGURE 14. Distribution of nominal Obesoconnus species, with comparison of aedeagi and dorsal habitus of males.

FIGURES 1–2. Obesoconnus asymmetricus sp. n. (1); and O. pallidus (2), dorsal habitus of holotype males.

FIGURES 3–5. Obesoconnus asymmetricus sp. n., head, pronotum and elytral base in dorsal view (3); head, prothorax and anterior region of pterothorax in ventral view (4), pterothorax in ventral view (5).

FIGURES 6–13. Obesoconnus asymmetricus sp. n. (6–9); and O. pallidus (10–13), aedeagus in ventral (6, 8, 10, 12) and lateral (7, 9, 11, 13) views.