Siamites sabahensis, Jałoszyński, 2020

Jałoszyński, Paweł, 2020, Four new species of the Oriental genus Siamites Franz (Coleoptera, Staphylinidae Scydmaeninae), Zootaxa 4751 (1), pp. 187-195 : 193-194

Siamites sabahensis sp. n.

( Figs 19–24 )

Type material. Holotype: E MALAYSIA (Sabah): ♂, two labels: “ SABAH: Poring Hot / Spring , 500 m / 7.V.1987 / Burckhardt - Löbl” [white, printed]; “ SIAMITES / sabahensis m. / det. P. Jałoszyński, 2020 / HOLOTYPUS ” [red, printed] ( MHNG).

Diagnosis. Male macrophthalmous; head with four separate tufts of bristles evenly distributed along posterior margin of vertex; aedeagus with large distal plate strongly constricted at base and with a pair of apical hooks.

Description. Body of male ( Fig. 19 ) moderately convex and moderately slender, uniformly light brown, covered with yellowish vestiture. BL 0.93 mm.

Head ( Fig. 20 ) broadest at large, strongly convex and coarsely faceted eyes, HL 0.13 mm, HW 0.18 mm; tem- pora in dorsal view slightly shorter than eyes; vertex with indistinct posteromedian impression, strongly transverse; frons confluent with vertex, with shallow median impression between weakly elevated supraantennal tubercles. Punctures on vertex obscured by bristles, those on frons fine, inconspicuous. Vestiture of head dorsum ( Fig. 20 ) composed of four separate tufts of dense and relatively short bristles evenly distributed along posterior margin of vertex, outer tufts slightly larger than inner pair; long and thick sparse bristles directed posterodorsad and situated slightly in front of posterior tufts; and sparse, suberect setae on frons. Antennae short, with moderately strongly broadened, indistinctly delimited tetramerous club, AnL 0.38 mm; scape and pedicel strongly elongate; antennomeres III–VII each about as long as broad, VIII–X each strongly transverse, XI distinctly shorter than IX–X com- bined, narrower than X, almost as long as broad.

Pronotum subconical with broad anterior margin, broadest near posterior third; PL 0.25 mm, PW 0.25 mm. All margins weakly and evenly rounded; lateral carinae barely discernible, blunt, marked in posterior third of pronotum; base with transverse groove distinctly deepened at each end. Punctures on pronotum fine and sparse, unremarkable; setae sparse, suberect, moderately long.

Elytra slightly flattened, together oval, broadest distinctly in front of middle; EL 0.55 mm, EW 0.40 mm, EI 1.38; humeral calli weakly marked, each with indistinct and rounded humeral carina not exceeding 1/4 of elytral length; basal impressions shallow and short; apices of elytra rounded together. Punctures on elytra more distinct and denser than those on pronotum but superficial and inconspicuous; setae sparse, short, suberect.

Wings long and functional.

Aedeagus ( Figs 21–24 ) elongate; AeL 0.13 mm; median lobe in ventral view cup-shaped with large apical plate projecting from ostium, plate constricted in basal region; endophallus with indistinctly delimited, moderately darkly sclerotized structures (very dark area visible near middle of median lobe in Figs 21 and 22 is an artifact); parameres short and broad, each with three long apical setae.

Female. Unknown.

Distribution. East-northern Borneo ( Fig. 25 ).

Etymology. After Sabah.

Remarks. The four tufts of bristles visible on the vertex in S. sabahensis seem to be a result of fusion of the lateralmost tufts from the original number of six. This character may be helpful to identify S. sabahensis , but examination of the uniquely shaped aedeagus is necessary to confirm determination.

Figures

FIGURE 25. Distribution of nominal Siamites species.

FIGURES 19–24. Siamites sabahensis s sp. n., dorsal habitus (19); head in anterodorsal view (20); aedeagus in ventral (21, 23) and lateral (22, 24) views.