Stenichnus (Stenichnus) lackneri, Jałoszyński, Paweł, 2016

Jałoszyński, Paweł, 2016, Stenichnus lackneri sp. n. of Japan (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4097 (1), pp. 147-150 : 148-149

Stenichnus (Stenichnus) lackneri sp. n. ( Figs 1–6 )

Type material studied. Holotype: JAPAN (Kagoshima Prefecture): ♂, two labels: " JAPAN, KAGOSHIMA Pref. / Tokunoshima Is., Amagi-dake, / primary forest, 27.iv.-7.v.2013 / sifted / T. LACKNER leg." [white, printed], " STENICHNUS (s. str.) / lackneri m. / Jałoszyński, 2016 / HOLOTYPUS " [red, printed] ( MNHW).

Diagnosis. BL nearly 2 mm; frons, vertex and pronotum nearly impunctate, elytra covered with large, dense and distinct punctures; profemur of male with indistinctly concave dorsal margin in distal fourth; aedeagus in ventral view with narrow and deep rounded apical emargination and large subtrapezoidal plate in subapical region.

Description. BL 1.98 mm; body of male ( Fig. 1 ) moderately slender, strongly convex, light brown with silverish vestiture of setae.

Head broadest at large and strongly projecting eyes, HL 0.33 mm, HW 0.40 mm; vertex weakly convex, transverse, anteriorly confluent with frons; frons between eyes flattened, subtriangular; supraantennal tubercles distinct. Punctures on vertex and frons very fine and sparse, barely noticeable, cuticle glossy; frons and vertex nearly asetose, moderately long and suberect setae present only on clypeus and tempora. Antennae very slender, AnL 1.00 mm, antennomeres I–VII each elongate, VIII–X each about as long as broad, XI much shorter than IX–X together, about twice as long as broad, with blunt apex.

Pronotum in dorsal view subtrapezoidal, broadest near anterior fourth, PL 0.50 mm, PW 0.48 mm; anterior margin weakly rounded; sides in anterior third strongly rounded, in posterior third slightly concave; posterior corners obtuseangled and broadly rounded; posterior margin weakly arcuate. Base of pronotum with transverse line composed of numerous small but distinct and slightly irregularly distributed punctures. Punctures on pronotal disc as inconspicuous as those on frons and vertex; setae long, sparse and suberect.

Elytra oval, strongly convex, broadest distinctly in front of middle; EL 1.15 mm, EW 0.83 mm, EI 1.39; basal elytral impressions very shallow; humeral calli weakly marked; elytral apices separately rounded. Punctures on elytra distinct, moderately large and deep and with relatively sharp margins, in anterior half separated by spaces smaller than diameters of punctures, posteriorly punctures reducing in diameter and depth; setae long, sparse, suberect to erect.

Legs moderately long and slender, profemur in subapical region with slightly concave dorsal margin (best visible in lateral view, as in Fig. 1 ).

Aedeagus ( Figs 3–6 ) elongate, AeL 0.33 mm; median lobe in ventral view with distinctly emarginate apex, slightly constricted at middle, with large subtrapezoidal ventral plate and membranous internal sac located in sub-basal region, lacking any sclerotized internal structures; parameres slender, each with several apical and subapical setae.

Female. Unknown.

Etymology. This species is dedicated to its collector, Tomáš Lackner.

Distribution. Japan, Ryukyus, Tokunoshima Island ( Fig. 2 ).

Remarks. No other East Palaearctic species of Stenichnus has the aedeagus with deeply and narrowly emarginate apex; this character alone is sufficient to identify St. lackneri . Diagnostic characters of all species of Stenichnus known to occur in Japan are compiled in Table 1 .

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Figures

FIGURES 1 – 2. Stenichnus lackneri. Dorsal habitus of holotype male (1); distribution of Stenichnus species in Japan (2).

FIGURES 3 – 6. Stenichnus lackneri. Aedeagus in ventral (3, 4) and lateral (5, 6) views.

Tables

TABLE 1. Diagnostic characters of Stenichnus species known to occur in Japan.

	St. pollens (Sharp)	St. minipollens Jałoszyński	St. bellulus Jałoszyński	St. totoro Jałoszyński
Body length	2.02 mm	1.59 mm	1.49−1.60 mm	2.12−2.21 mm
Elytral index	1.30	1.34	1.37−1.44	1.26−1.36
Antebasal pronotal pits	numerous	numerous	four (sometimes indistinct)	numerous
Antennomere VI	about twice as long as broad	about as long as broad	nearly twice as long as broad	about twice as long as broad
Antennomere VIII	about as long as broad	about as long as broad	distinctly transverse	about as long as broad
Distal apical margin of profemur in male, lateral view	straight	straight	weakly convex	straight