Microscydmus (Microscydmus) omogonus, Jałoszyński, 2019

Jałoszyński, Paweł, 2019, Unexpected diversity of Microscydmus Saulcy & Croissandeau in Japan (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 4679 (3), pp. 539-552 : 549

Microscydmus (Microscydmus) omogonus sp. n.

( Figs 8 , 16 , 24 , 32 )

Type material. Holotype: JAPAN (Ehime Pref.): ♂, two labels: "(SHIKOKU) / Omogo-kei / Ehime Pref. / 26. V. 1969 / M. Sakai leg." [white, printed]; " MICROSCYDMUS (s. str.) / omogonus m. / P. Jałoszyński, 2019 / HOLOTYPUS " [red, printed] ( EUMJ).

Diagnosis. Body length ~ 0.8 mm; frons and vertex with fine and shallow but distinct, dense punctures; bristles on tempora and vertex well-visible; protibia not thickened distad, unmodified, with apical margin transverse in relation to the long axis of tibia; aedeagus with asymmetrical tubular endophallic structure in submedian region; parameres weakly curved.

Description. Body of male ( Fig. 8 ) moderately slender, slightly flattened, pigmentation moderately dark brown, vestiture light brown; BL 0.83 mm.

Head ( Fig. 16 ) broadest at eyes, HL 0.13 mm, HW 0.18 mm; tempora weakly arcuate, distinctly shorter than eyes; posterior margin of vertex nearly straight, vertex and frons confluent and convex, except for distinctly flattened frontal area between and slightly behind supraantennal tubercles; supraantennal tubercles weakly elevated but welldefined; eyes large, strongly convex and coarsely faceted. Frons and vertex uniformly and evenly covered with small, shallow, moderately distinct, dense punctures; setae sparse, short and suberect, bristles on tempora and vertex distinct; long posterolateral setae on vertex not found.Antennae slender, AnL 0.36 mm, antennomeres I and II stron- gly elongate, III–X each strongly transverse, XI about as long as broad.

Pronotum in dorsal view nearly circular, broadest distinctly in front of middle, PL 0.23 mm, PW 0.23 mm; anterior margin weakly arcuate; anterior corners not marked; sides strongly rounded in anterior half, weakly so in posterior half; posterior pronotal corners distinct, obtuse-angled; posterior margin weakly arcuate; pronotal base with distinct, relatively long transverse groove, lateral pits very small, barely discernible. Punctures on disc fine, inconspicuous; setae sparse, short, suberect; lateral bristles sparse and moderately long.

Elytra together oval, broadest distinctly in front of middle, EL 0.48 mm, EW 0.33 mm, EI 1.46; humeral calli distinct; elytral base with large and deep basal impression; adsutural area indistinctly impressed in anterior half; apices of elytra separately rounded. Punctures on elytra more distinct than those on pronotum, very dense, but very shallow and with diffuse margins; setae short, sparse and nearly recumbent.

Protibia ( Fig. 24 ) not thickened distad, unmodified, with apical margin transverse in relation to the long axis of tibia.

Aedeagus ( Fig. 32 ) slender, AeL 0.13 mm, endophallus with asymmetrical long median tubular component funnel-like broadened in its proximal portion; parameres curved in proximal half, nearly straight in distal half, each with one apical seta.

Female. Unknown.

Distribution. Japan, northern Shikoku.

Etymology. Locotypical, after Omogo Gorge (= Omogo-kei).

Remarks. Microscydmus omogonus has the aedeagus most similar to that of its Far Eastern congener, M. pusio Kurbatov, 2006 that occurs on the Kunashir Is. (a disputed territory of the southern Kuril Islands, until 1945 belonging to Japan, currently to Russia). The endophallus in these species is clearly asymmetrical and contains a recurved tubular component broad proximally and narrowing distad. In M. pusio this structure is longer than half length of the median lobe, nearly parallel-sided in the proximal third, and gradually narrowing; in M. omogonus this structure is as long as about 1/3 of median lobe, and its proximal portion forms a funnel-like, inversely subconical and abrupt broadening. Among Japanese species, the unmodified protibia makes M. omogonus similar to M. oharaensis , but aedeagi of these species clearly differ, and M. omogonus is distinctly larger than its Ryukyuan relative.

Figures

FIGURES 1–8. Dorsal habitus of males. Microscydmus okinawanus sp. n. (1); M. oharaensis sp. n. (2); M. nishimeanus sp. n. (3); M. kochiensis sp. n. (4); M. elytratus sp. n. (5); M. tibialis sp. n. (6); M. yusuharanus sp. n. (7); M. omogonus sp. n. (8).

FIGURES 9–16. Heads of males in anterodorsal view. Microscydmus okinawanus sp. n. (9); M. oharaensis sp. n. (10); M. nishimeanus sp. n. (11); M. kochiensis sp. n. (12); M. elytratus sp. n. (13); M. tibialis sp. n. (14); M. yusuharanus sp. n. (15); M. omogonus sp. n. (16). Arrowheads show posterolateral vertexal setae.

FIGURES 17–24. Apices of male protibia in dorsal (17–21, 22–24) and ventral (22) views. Microscydmus okinawanus sp. n. (17); M. oharaensis sp. n. (18); M. nishimeanus sp. n. (19); M. kochiensis sp. n. (20); M. elytratus sp. n. (21); M. tibialis sp. n. (22); M. yusuharanus sp. n. (23); M. omogonus sp. n. (24).

FIGURES 25–32. Aedeagus in ventral view. Microscydmus okinawanus sp. n. (25); M. oharaensis sp. n. (26); M. nishimeanus sp. n. (27); M. kochiensis sp. n. (28); M. elytratus sp. n. (29); M. tibialis sp. n. (30); M. yusuharanus sp. n. (31); M. omogonus sp. n. (32).