Hlavaciellus concavus, Jałoszyński, 2021

Jałoszyński, Paweł, 2021, Six new species of the Oriental genus Hlavaciellus Jałoszyński (Coleoptera Staphylinidae, Scydmaeninae), Zootaxa 4966 (1), pp. 1-15 : 8-10

Hlavaciellus concavus sp. n.

( Figs 17–20 , 25 )

Type material. Holotype: INDONESIA (Sumatra): ♂, two labels: “ SUMATRA: Jambi / Mt Kerinci , 1750- / 1850 m, 11-12.XI. / 1989, Agosti, Löbl / Burckhardt #11” [white, printed], “ HLAVACIELLUS / concavus m. / P. Jałoszyński, 2021 / HOLOTYPUS” [red, printed] ( MHNG).

Diagnosis. Body very large, exceeding 2.2 mm in length; head in males with large and deep median impression between eyes filled with short and dense setae directed toward its center; each of antennomeres 3–10 elongate; aedeagus in ventral view moderately stout, 3 times as long as broad and distinctly narrowing both toward apex and base; parameres with thin subapical setae and conspicuously broadened and then rapidly narrowed apical portions.

Description. Body of male ( Fig. 17 ) stout, strongly convex, uniformly light brown; setae distinctly lighter than cuticle; BL 2.23 mm.

Head ( Fig. 18 ) broadest at large, strongly convex and coarsely faceted eyes, HL 0.30 mm, HW 0.60 mm; frons and vertex with large and deep circular median impression. Punctures on frons in front of impression fine and inconspicuous; setae between supraantennal tubercles and on sides of impression long, moderately dense and suberect, impression densely filled with short, recumbent setae directed toward its center. Antennae slender, AnL 1.63 mm, BL/AnL 1.37; scape indistinctly elongate, pedicel as long as broad, antennomeres 3–10 each elongate (4 and 5 weakly so), 11 slightly shorter than 9–10 combined, 2.2 ×as long as broad.

Pronotum subrectangular, equally broad at base and at anterior third; PL 0.68 mm, PW 0.93 mm, PI 0.73; anterior margin weakly rounded; sides with finely crenulate lateral carinae, in posterior 2/3 distinctly concave; posterior corners sharp-angled but 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 1.25 mm, EW 1.08 mm, EI 1.16; subhumeral lines sharply marked, each developed as step-wise border between elevated humeral region and median area, as long as 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 19–20 ) elongate but not very slender; AeL 0.45 mm; median lobe in ventral view 3 times as long as broad, broadest near sub-basal fourth and with broadly rounded sides near base, but lateral margins straight in distal 2/3; endophallic structures distinct, in ventral view appearing as two elongate elements, but in lateral view one tubular structure can be seen bent at sharp angle near base of median lobe; parameres with thin subapical setae, each with broadened and then rapidly narrowed distal region.

Female. Unknown.

Distribution. Sumatra ( Fig. 25 ).

Etymology. Concavus is a Latin adjective meaning “hollow, concave” and refers to the large median concavity on the head.

Remarks. The conspicuous round impression densely filled with short setae on the head is a unique apomorphy of this species; in addition, H. concavus has the largest adults of all known members of this genus, exceeding 2.2 mm in length.

Figures

FIGURE 25. Distribution of nominal species of Hlavaciellus.

FIGURES 17–20. Hlavaciellus concavus sp. n., male. Dorsal habitus (17); head in anterior view (18); aedeagus in ventral (19) and lateral (20) views.