Siamites complicatus, Jałoszyński, Paweł, 2013

Jałoszyński, Paweł, 2013, A new species of Siamites Franz (Coleoptera, Staphylinidae, Scydmaeninae) from Thailand, Zootaxa 3734 (3), pp. 385-390 : 386-389

Siamites complicatus sp. n.

( Figs. 1–12 )

Type material. Holotype: THAILAND (Krabi Prov.): ♂, two labels: " THAILAND: Krabi province / 10 km N Krabi. Pitfalls / 8°09'N, 98°50'E / October 1991, O. Martin leg. / Zoologisk Museum, København" [white, printed]; " SIAMITES / complicatus m. / det. P. Jałoszyński, '13 / HOLOTYPUS " [red, printed] (ZMUC). Paratypes (2 ♂♂): same data as holotype, except for yellow " paratypus " label (ZMUC, cPJ).

Diagnosis. Aedeagus with a pair of corkscrew-like lateral apical sclerites.

Description. Body of male ( Figs. 1–2 ) strongly convex and relatively slender, brown with slightly lighter legs and palps, covered with yellowish vestiture. BL 1.10–1.13 mm.

Head ( Figs. 3–4 , 6–7 ) broadest at large, strongly convex and coarsely faceted eyes, HL 0.18–0.20 mm, HW 0.23–0.25 mm; 'neck region' hidden inside prothorax with dorsal median expansion adjacent to posterior part of vertex; tempora in dorsal view distinctly shorter than eyes; vertex slightly impressed, strongly transverse; frons confluent with vertex, flattened in middle and rapidly declining anterad; supraantennal tubercles weakly marked. Vestiture of head dorsum ( Fig. 6 ) composed of four rosettes of dense bristles forming a transverse arc on vertex; long and sparse suberect to erect bristles on posterior part of frons; thin, sparse and suberect setae on anterior part of frons; and long, erect and curved bristles on tempora. Punctures on frons and vertex unremarkable, fine and sparse. Antennae ( Figs. 1–2 ) slightly longer than head and pronotum, AnL 0.48; scape and pedicel strongly elongate; antennomere III about as long as broad; antennomeres IV–VII each slightly longer than broad; VIII–X each strongly transverse; XI distinctly narrower than X, slightly longer than broad.

Prothorax ( Figs. 1–2 , 8 ) elongate, with subrectangular pronotum only slightly narrowing anterad and with well-marked anterior and posterior corners, broadest in posterior fourth; PL 0.29–0.30 mm, PW 0.25 mm. Anterior margin weakly arcuate; anterior pronotal angles slightly obtuse; lateral margins rounded; posterior angles slightly obtuse; posterior margin weakly arcuate; pronotum with distinct carinate lateral edges in posterior half and arcuate transverse ante-basal groove deepened at each end and indistinctly shallower in middle. Vestiture of pronotum composed of sparse and suberect thin setae distributed on dorsum and thick erect bristles on sides; prosternum ( Fig. 8 ) with a transverse row of eight bunches of dense bristles along anterior margin. Punctures on pronotum fine and sparse, unremarkable.

Elytra ( Figs. 1–2 ) more convex than pronotum, oval, broadest distinctly anterior to middle; EL 0.63 mm, EW 0.45–0.46 mm, EI 1.35–1.39; humeral calli weakly marked, each with indistinct humeral carina extending to 1/4 of elytral length; basal foveae small but located in large and deep basal impression; apices of elytra separately rounded. Vestiture uniform, composed of short, moderately dense and suberect setae; punctures fine and sparse. Hind wings well developed.

Mesoventrite ( Fig. 9 ) with large asetose impressions, strongly projecting latero-ventrally mesocoxal projections and moderately expanding ventrally keel-like mesoventral intercoxal process; vestiture of ventrite with bunches of dense bristles directed laterally along anterior margin of mesocoxal cavities, several bristles directed posteriorly on antero-mesal margin of mesocoxal cavities; dense setae directed posteriorly on mesoventral intercoxal process; and lateral bristles mixed with thin setae on mesanepisterna.

Metaventrite ( Fig. 9 ) with several rosettes of dense bristles along posterior margin of mesocoxal cavities.

Each abdominal sternite ( Fig. 9 ; only abdominal ventrites I–III shown) with several bunches of dense setae along posterior margin.

Legs moderately long and slender; mesocoxae ( Fig. 9 ) with two bunches of dense bristles on posterior margin.

Aedeagus ( Figs. 10–12 ) stout and small; AeL 0.13 mm; median lobe divided by transverse fold into basal and apical parts; apical part with lateral sclerites each forming a spiral with tip of sclerite directed mesad; internal sclerotization complex, in ventral view with large subtriangular and dark structure in middle and subconical apex of copulatory piece projecting distally; parameres short but slender, each with three apical setae.

Female. Unknown.

Distribution. Southern Thailand, Krabi Prov. ( Fig. 5 ).

Etymology. The name complicatus refers to the structure of the aedeagus, far more complex than that of S. loebli .

Remarks. Siamites complicatus clearly differs from S. loebli not only in the aedeagus with lateral apical corkscrew-like sclerites (absent in S. loebli ) but also in distinctly stouter body, with the elytral index 1.35–1.39, while males of S. loebli have more slender elytra, with EI = 1.44–1.52 (and females 1.50–1.55). To date, Siamites was known only from two localities in Central Thailand: the Kaeng Krachan and Khao Yai National Parks ( Fig. 5 ). The discovery of the new species in the Krabi Province extends the range of Siamites nearly 600 km southward.

Figures

FIGURES 1 – 5. Habitus and distribution of Siamites Franz. Siamites complicatus sp. n., dorsal (1) and lateral (2) habitus of male; head of male in lateral (3) and antero-dorsal views (4). Distribution of Siamites (5), circle - Siamites complicatus sp. n.; squares - Siamites loebli Franz.

FIGURES 6 – 9. Siamites complicatus sp. n. Head in postero-dorsal (6) and ventral (7) views; prothorax in ventral view (8) and pterothorax in ventral view (9) (distal part of abdomen omitted).

FIGURES 10 – 12. Siamites complicatus sp. n. Aedeagus in ventral (10), dorsal (11) and lateral (12) views.