Microscydmus (Microscydmus) oharaensis, Jałoszyński, 2019

Jałoszyński, Paweł, 2019, Unexpected diversity of Microscydmus Saulcy & Croissandeau in Japan (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 4679 (3), pp. 539-552 : 541-542

Microscydmus (Microscydmus) oharaensis sp. n.

( Figs 2 , 10 , 18 , 26 )

Type material. Holotype: JAPAN (Okinawa Pref.): ♂, two labels: " JAPAN, OKINAWA Pref. / IRIOMOTEJIMA / ÔHARA env. / 19 IX 2003, subtr. forest / rotten wood, P. Jałoszyński " [white, printed]; " MICROSCYDMUS (s. str.) / oharaensis m. / det. P. Jałoszyński, '15 / HOLOTYPUS " [red, printed] ( NSMT).

Diagnosis. Body length 0.7 mm; vertex evenly punctate; head with long, well-visible bristles, especially long on posterior margin of vertex; protibia in male slightly tapered in apical region, lacking apical comb; aedeagus with a pair of subapical round structures; parameres nearly straight.

Description. Body of male ( Fig. 2 ) slender, slightly flattened, pigmentation brown, with head and elytra slightly darker than pronotum, vestiture light brown; BL 0.70 mm.

Head ( Fig. 10 ) broadest at eyes, HL 0.13 mm, HW 0.16 mm; tempora weakly arcuate, slightly shorter than eyes; posterior margin of vertex slightly arcuate, vertex and frons confluent and convex; supraantennal tubercles weakly elevated but well-defined; eyes large, strongly convex and coarsely faceted. Frons and vertex covered with small, shallow but dense punctures with diffuse margins; setae sparse, short and suberect; bristles on tempora, and especially on posterior margin of vertex, long and relatively dense, directed posterad. Antennae slender, AnL 0.30 mm, antennomeres I and II strongly elongate, III–X each transverse, XI about as long as broad.

Pronotum in dorsal view nearly circular, broadest distinctly in front of middle, PL 0.18 mm, PW 0.20 mm; anterior margin confluent with sides, anterior corners not marked, sides strongly rounded in anterior third and weakly so in posterior half, posteriorly strongly convergent toward base, posterior margin nearly straight; posterior corners well-defined, obtuse-angled; pronotal base with a well-defined, short transverse groove, additionally with one tiny pit near each hind corner. Punctures on disc fine and inconspicuous, similar to those on head; setae sparse, short, suberect; lateral bristles long and dense, especially in posterior half of pronotum.

Elytra together oval, broadest slightly in front of middle, EL 0.40 mm, EW 0.25 mm, EI 1.60; humeral calli distinct; elytral base with large and deep basal impression; adsutural region on each elytron not impressed; apices of elytra separately rounded. Punctures fine and inconspicuous; setae short, sparse and nearly recumbent.

Protibia ( Fig. 18 ) slender, slightly tapered in apical region, lacking apical comb.

Aedeagus ( Fig. 26 ) moderately slender, AeL 0.13 mm, endophallus lightly sclerotized, with two round subapical structures; parameres nearly straight, slightly broadened distad, each with one apical seta.

Female. Unknown.

Distribution. Japan, Yaeyama Archipelago of the Ryukyus, Iriomote-jima.

Etymology. Locotypical, after Ôhara, a town on Iriomote Is.

Remarks. Among Japanese species, M. oharaensis externally resembles most M. yusuharanus sp. n. described below. They share a similar body form and length, and they both lack the apical protibial comb in the male. The protibial apex in the male of M. oharaensis has its apical margin transverse in relation to the long axis of tibia, and the apical spurs are inserted at the apex. In M. yusuharanus , the protibial apex forms a short, tapered lobe with its apical margin oblique in relation to the long axis of tibia, and the spurs are inserted at its base, far from the tibial apex. The tempora in M. oharaensis are only slightly shorter than eyes; in M. yusuharanus they are yet shorter. The aedeagi of these species clearly differ, both in endophallic structures, and in the relative length of parameres.

The individual that is fixed as a holotype was sifted from a hollow in a large rotten log of a deciduous tree.

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).