Cephennomicrus ushimanus, Jałoszyński, 2021

Jałoszyński, Paweł, 2021, Two new species of Cephennomicrus in the Ryūkyū Archipelago (Coleoptera Staphylinidae, Scydmaeninae), Zootaxa 4938 (5), pp. 581-587 : 584

Cephennomicrus ushimanus sp. n.

( Figs 6–10 , 11 )

Type material. Holotype: JAPAN ( Amami Ôshima Island ): ♁, two labels: “JAPAN, KAGOSHIMA-KEN, / AMAMI - OSHIMA, YUI-DAKE / near SETOUCHI, 24.3.2010 / T. LACKNER lgt., sifted” [white, printed], “ CPHENNOMICRUS / ushimanus m. / P. Jałoszyński, 2021 / HOLOTYPUS” [red, printed] ( NSMT).

Diagnosis. Body small, ~ 0.85 mm in length, covered with short but well-noticeable and dense weakly suberect setae, lacking macrosetae; head in male unmodified; punctures on head, pronotum and elytra fine, superficial and inconspicuous, cuticle moderately glossy; antennal club dimerous and sharply demarcated; pronotum with sides strongly convergent posterad and with two pairs of distinct antebasal pits not connected by transverse groove; aedeagus in ventral view bottle-shaped, stout, with large proximal region and rapidly narrowed, subtrapezoidal and truncate distal area; in lateral view apical margin distinctly slanting; ventral diaphragm moderately large and circular, situated at middle of median lobe; parameres slender, each with single apical seta.

Description. Body of male ( Fig. 6 ) moderately stout, strongly convex, uniformly light brown; setae slightly lighter than cuticle and well-discernible; BL 0.85 mm.

Head broadest at large, moderately strongly convex and finely faceted eyes, HL 0.08 mm, HW 0.23 mm; vertex and frons between eyes evenly, weakly convex; frontal glands not discernible. Punctures on frons and vertex fine and inconspicuous; setae short and nearly recumbent but dense and well-discernible under magnification 40 × Antennae slender, with sharply delimited, large dimerous club, AnL 0.36 mm; antennomeres 1–2 each elongate, 3 indistinctly transverse, 4 about as long as broad, 5–8 each slightly elongate, 9 about as long as broad, 10 slightly transverse and twice as broad as 9, 11 slightly longer and about as broad as 10, about 1.4 × as long as broad.

Pronotum subtrapezoidal, broadest near anterior third; PL 0.28 mm, PW 0.35 mm; anterior margin in strictly dorsal view indistinctly concave; lateral margins strongly rounded in anterior third, slightly concave near middle, indistinctly microserrate and weakly convergent posterad in posterior third; posterior corners obtuse-angled; posterior margin with barely discernible, shallow emargination in front of scutellar shield. Pronotal base with two pairs of small but deep circular pits, inner pair not connected by groove, distance between inner pits nearly 4 × as wide as between inner and outer pit. Punctures on pronotum extremely fine, inconspicuous; setae dense, moderately long, weakly suberect.

Elytra together oval, broadest in anterior third; EL 0.50 mm, EW 0.43 mm, EI 1.18; humeral calli and short basal impressions distinct; subhumeral lines indistinct, diffuse; sides of elytra strongly rounded; elytral apices separately rounded. Punctures and setae similar to those on pronotum.

Hind wings long and functional.

Legs moderately long and slender, unmodified.

Aedeagus ( Figs 7–10 ) stout, bottle-shaped and relatively small in relation to body; AeL 0.18 mm; median lobe in ventral view with large proximal region and rapidly narrowed, small subtrapezoidal distal region with truncate apex; ventral diaphragm moderately large, circular and situated at middle, with dark lentiform internal sclerotization (visible in Fig. 8 ) to which transverse muscle fibers are attached; in lateral view aedeagus with distinctly slanting apical margin and small subtriangular apical projection bent dorsad; endophallus with two large lateral structures in apical region, lacking tubular elements. Parameres slender, each with one apical seta.

Female. Unknown.

Distribution. Japan, Amami Ôshima ( Fig. 11 ).

Etymology. Named after the Ôshima island of the Amami Archipelago; Ushima in the Amami (Shimayumuta) dialect.

Remarks. This species is very interesting for evolutionary and biogeographic reasons. Its aedeagus closely resembles that of C. cactiformis (Jałoszyński & Hoshina) known to inhabit Tsushima Island situated in-between the Tsushima Strait and Korea Strait, halfway between Kyūshū and the Korean Peninsula, nearly 700 km north of Amami Ôshima. The proportions between the large basal and small apical regions of the median lobe are different in these species, and the general shape of the median lobe in lateral view is clearly different. Moreover, C. cactiformis was named so because of several pairs of conspicuously long and erect macrosetae on the sides and base of pronotum and sides of elytra, whereas C. ushimanus lacks such setae.

Figures

FIGURE 11. Distribution of nominal Cephennomicrus species within Japan, with aedeagus of each species in ventral view (that of C. tanakai based on Hoshina (2011)).

FIGURES 1–10. Cephennomicrus aji sp. n. (1–5) and C. ushimanus sp. n. (6–10). Dorsal habitus of holotype male (1, 6), and aedeagus in ventral (2, 4, 7, 9) and lateral (3, 5, 8, 10) views.