Hlavaciellus microtuberculatus Jałoszyński 2021, sp. n.
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Hlavaciellus
Hlavaciellus microtuberculatus

description: Hlavaciellus microtuberculatus sp. n.
(Figs 9–12, 25)
Type material. Holotype: MALAYSIA (Pahang): ♂, two labels: “ W. Malaysia: Pahang / Cameron Highlands / trail 9, 1400m, 27.3.93 / Löbl & Calame, #21” [white, printed], “ HLAVACIELLUS / microtuberculatus m. / P. Jałoszyński, 2021 / HOLOTYPUS” [red, printed] (MHNG). Paratypes (2 exx.): 1 ♀, same data as for holotype; 1 ♀, “ W. Malaysia: Pahang # 18b / Cameron Highls, 1550m / Gunung Jasar, trail 11 / Löbl & Calame, 24.3.93”; paratypes with yellow “PARATYPUS” labels (MHNG, cPJ).
Diagnosis. Body small, not reaching 2 mm in length and conspicuously stout, with elytra about as long as broad; head in males with unmodified frons and vertex, but in both sexes with pair of tiny, barely discernible submedian tubercles on vertex; pronotum slightly narrower than elytra; each of antennomeres 3–4 and 7–10 about as long as broad, and 5–6 each indistinctly elongate; aedeagus in ventral view stout, 3 times as long as broad and distinctly narrowing both toward apex and base; parameres with thin subapical setae.
Description. Body of male (Fig. 9) stout, strongly convex, uniformly dark brown; setae distinctly lighter than cuticle; BL 1.78 mm.
Head (Fig. 10) broadest at large, strongly convex and coarsely faceted eyes, HL 0.33 mm, HW 0.45 mm; frons and vertex unmodified, weakly convex, vertex with pair of tiny submedian tubercles (barely discernible; observations at various angles are necessary to notice tubercles). Punctures on frons and vertex fine and inconspicuous; setae long, moderately dense and suberect. Antennae slender, AnL 1.23 mm, BL/AnL 1.45; scape indistinctly elongate, antennomeres 3–4 and 7–10 each about as long as broad, and 5–6 each indistinctly elongate, 11 distinctly shorter than 9–10 combined, twice as long as broad.
Pronotum subrectangular, broadest near anterior third but indistinctly narrowing toward base; PL 0.58 mm, PW 0.85 mm, PI 0.68; anterior margin weakly rounded; sides with finely crenulate lateral carinae, in posterior 2/3 straight; posterior corners nearly right-angled and with blunt tips; posterior margin shallowly bisinuate; pronotal disc strongly convex, with area at each posterior corner distinctly impressed; antebasal pits slightly closer to posterior than to lateral margins. Punctures on pronotum fine and inconspicuous; setae long, dense, suberect.
Elytra together oval, broadest distinctly in front of middle; EL 0.88 mm, EW 0.93 mm, EI 0.95; subhumeral lines sharply marked, each developed as step-wise border between elevated humeral region and median area, slightly exceeding 0.3 EL; sides of elytra strongly rounded; elytral apices separately rounded. Punctures and setae similar to those on pronotum.
Legs long and slender, unmodified.
Aedeagus (Figs 11–12) elongate but not very slender; AeL 0.30 mm; median lobe in ventral view 3 times as long as broad, broadest near sub-basal third and with broadly rounded sides; endophallic structures distinct, in ventral view appearing as single elongate subtriangular element, but in lateral view two separate tubular structures can be seen, proximal one bent at sharp angle near base of median lobe; parameres with thin subapical setae.
Female. Externally similar to male but with clearly shorter antennae in relation to body. BL 1.78–1.85 mm; HL 0.30–0.40 mm, HW 0.45–0.48 mm, BL/AnL 1.82–1.95; PL 0.55–0.58 mm, PW 0.85–0.90 mm, PI 0.64–0.65; EL 0.90 mm, EW 0.90–0.93 mm, EI 0.97–1.00.
Distribution. Peninsular Malaysia (Fig. 25).
Etymology. The adjective microtuberculatus refers to the pair of tiny tubercles on the vertex in both sexes.
Remarks. Hlavaciellus microtuberculatus belongs to small-bodied species, clearly below 2 mm in length. The most conspicuous feature of this otherwise unremarkable species is a very stout body, with elytra about as long as broad, or even indistinctly broader than long; in all remaining species the elytra are at least slightly elongate.
description: Published as part of Jałoszyński, Paweł, 2021, Six new species of the Oriental genus Hlavaciellus Jałoszyński (Coleoptera Staphylinidae, Scydmaeninae), pp. 1-15 in Zootaxa 4966 (1) on pages 5-7, DOI: 10.11646/zootaxa.4966.1.1, http://zenodo.org/record/4729328