Cephennomicrus tenebrosus, Jałoszyński, 2024

Jałoszyński, Paweł, 2024, A new species and new records of Cephennomicrus Reitter in Japan (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 5523 (1), pp. 139-145 : 140-142

Cephennomicrus tenebrosus sp. nov.

( Figs 1–8 )

Type material. Holotype: JAPAN (Okinawa Is.): ♂, three labels: “JAPAN, OKINAWA Is. / Nishihara-chō, / Nishihara Undōkōen / 24 III 2018 / leg. N. Tokushige ” [white, printed], the same data are repeated in Japanese on second label, “ CEPHENNOMICRUS / tenebrosus m. / P. Jałoszyński, 2024 / HOLOTYPUS ” [red, printed] ( NSMT).

Diagnosis. Member of Cephennomicrus nomurai species group (based on median longitudinal pronotal groove) with dark brown body, in male frons weakly elevated and delimited laterally by narrow longitudinal impressions, trimerous antennal club so slender that not delimited from proximal antennomeres, with antennomere 11 conspicuously elongate, 2.5 times as long as broad; aedeagus in ventral view drop-shaped, apex with pair of elongate lateral lobes curved mesally, endophallus with three pairs of elongate sclerites: median pair with each sclerite approximately L-shaped and touching at middle, sublateral pair with each sclerite bifurcate, and lateral outer pair with each sclerite strongly elongate and curved mesally.

Description. Body of male ( Fig. 1 ) stout, strongly convex, dark brown with lighter tibiae, tarsi and antennae; setae distinctly lighter than cuticle; BL 1.08 mm.

Head broadest at large, strongly convex and coarsely faceted eyes, HL 0.13 mm, HW 0.26 mm; frontal glands indiscernible; frons weakly elevated and laterally delimited by narrow impressions; supraantennal tubercles distinct but weakly elevated. Punctures on frons and vertex inconspicuous, fine; setae sparse, short and suberect. Antennae conspicuously slender, with trimerous clubs so slender that apparently not delimited,AnL 0.60 mm; all antennomeres elongate, 1–2, 7, 10 and 11 each strongly so, remaining antennomeres slightly elongate, antennomere 11 2.5 times as long as broad.

Pronotum bell-shaped, broadest between middle and anterior third and distinctly narrowing posteriorly; PL 0.33 mm, PW 0.39 mm; anterior margin weakly convex; lateral margins strongly rounded in anterior half, slightly concave behind middle and nearly straight in front of hind corners; hind corners nearly right-angled and blunt; posterior margin weakly arcuate. Pronotal disc with slightly microserrate lateral carinae, sharply marked median longitudinal groove, narrow transverse antebasal groove connecting small inner pits, and small outer pits slightly anterad inner pits. Punctures on pronotal disc fine, inconspicuous; setae moderately dense, short and weakly suberect, macrosetae lacking.

Elytra together oval, broadest slightly in front of middle; EL 0.63 mm, EW 0.53 mm, EI 1.19; humeral calli distinct; subhumeral lines lacking; sides of elytra strongly rounded; elytral apices separately rounded. Punctures more distinct than those on pronotum and dense, separated by spaces subequal to their diameters, but punctures are superficial and with diffuse margins so they appear indistinct. Setae similar to those on pronotum, macrosetae lacking.

Hind wings long and functional.

Legs moderately long and slender, unmodified.

Aedeagus ( Figs 2–5 ) stout, drop-shaped; AeL 0.28 mm; median lobe in ventral view broadest in basal region, with subtriangular blunt apex flanked by elongate lateral lobes curved mesally; endophallus complex and symmetrical, with six elongate sclerites: pair of median L-shaped sclerites touching at middle, submedian lateral pair each composed of two fused elongate sclerites, so that each pair appears as bifurcate, and long outer lateral sclerites curved mesally. Parameres slender, their apices not reaching apex of median lobe, each paramere with one apical and two subapical setae.

Female. Unknown.

Distribution. Okinawa Island ( Fig. 8 ).

Etymology. The adjective tenebrosus (Latin: dark, gloomy) alludes to the unusually dark body pigmentation.

Remarks. Adults of this species are conspicuously darkly pigmented, but only the aedeagus offers unambiguous features for identification. Among Japanese species with similarly drop-shaped aedeagi, the one of C. tenebrosus is most conspicuous because of the complex symmetrical set of endophallic sclerites containing a sublateral bifurcate pair. Moreover, this is the only known Cephennomicrus with lateral lobes flanking the apex of aedeagus in ventral view.

I have seen a female specimen of Cephennomicrus collected on Amami Ôshima Island, which strongly resembles C. tenebrosus in a dark body pigmentation and body length and proportions. However, its antennae are less slender, especially the antennomere 11 is less than twice as long as wide. It cannot be excluded that the unusual elongation of antennae is a male dimorphic character, but without either females from Okinawa Is. or males from the distant Amami Ôshima it is not possible to verify this suspicion.

Norihide Tokushige kindly provided further collecting details for the holotype: the specimen was found within the Nishihara Undôkôen Park under a stone.

Figures

FIGURE 8. Distribution of nominal Cephennomicrus species in Japan, with aedeagus illustrated for each species: a, C. tanakai Hoshina; b, C. japonigenus (Jałoszyński & Hoshina); c, C. cactiformis (Jałoszyński & Hoshina); d, C. ushimanus Jałoszyński; e, C. okinawanus (Jałoszyński, S. Arai & K.Arai); f, C. disjunctus (Jałoszyński, S. Arai & K. Arai); g, C. nagoanus Jałoszyński; h, C. aji Jałoszyński; i, C. tenebrosus Jałoszyński; j, C. nomurai (Jałoszyński & Hoshina); k, C. hobbiti (Jałoszyński & Hoshina); l, C. iriomotensis Jałoszyński; m, C. pseudojaponigenus Jałoszyński.

FIGURES 1–7. Cephennomicrus tenebrosus sp. nov., holotype (1–5), C. japonigenus Jałoszyński & Hoshina (6), and C. nagoanus Jałoszyński (7). Dorsal habitus (1), aedeagus in ventral (2, 4, 6, 7) and lateral (3, 5) views.