Cephennomicrus impressus, Jałoszyński, 2021

Jałoszyński, Paweł, 2021, Cephenniini of the Philippines. Part 5. Three new species of Cephennomicrus Reitter (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4975 (3), pp. 592-598 : 594-596

Cephennomicrus impressus sp. n.

( Figs 2 , 6–7 , 10 )

Type material. Holotype: PHILIPPINES (Palawan): ♂, three labels: “(PHILIPPINES) / Trident Mine (500 m) / nr. Nara, foot of / Victoria Peak / Palawan, 4. IX. 1985 / K. Ishikawa leg.” [white, printed], “Tullgren sample / of leaf litter” [white, printed], “ CEPHENNOMICRUS / impressus m. / P. Jałoszyński, 2021 / HOLOTYPUS ” [red, printed] ( EUMJ).

Diagnosis. Body extremely short, barely exceeding 0.5 mm in length, moderately stout and slightly flattened, with basic vestiture composed of short and dense, well-discernible setae, lacking macrosetae; antennal club trimerous; punctures on pronotum fine but distinct and dense, those on head and elytra inconspicuous; pronotum with two pairs of deep antebasal pits, inner pair connected by deep transverse impression; aedeagus in ventral view stout, drop-shaped, broadest in sub-basal region and with truncate, subtrapezoidal apex; endophallus with elongate, bellshaped structure in subapical region.

Description. Body of male ( Fig. 2 ) moderately stout, weakly convex, uniformly light brown; setae slightly lighter than cuticle; BL 0.56 mm.

Head broadest at large, moderately strongly convex and coarsely faceted eyes, HL 0.06 mm, HW 0.15 mm; vertex and frons evenly, weakly convex; frontal glands not discernible. Punctures and setae on frons and vertex very fine, barely discernible, shallow but dense. Antennae slender, with moderately sharply delimited, large trimerous club, AnL 0.23 mm; antennomeres 1–2 each elongate, 3–8 each about as long as broad or slightly transverse, 9 and 10 each distinctly transverse, 11 about as long as broad.

Pronotum subtrapezoidal, broadest near anterior third but weakly narrowing posterad; PL 0.18 mm, PW 0.23 mm; anterior margin weakly convex; lateral margins strongly rounded in anterior half, nearly straight in posterior half; posterior corners slightly obtuse-angled; posterior margin nearly straight. Pronotal base with two pairs of large and deep circular pits, inner pair connected by deep groove, distance between inner pits much wider than between inner and outer pit, which are separated by a narrow area that appears as a longitudinal wrinkle. Punctures on pronotum small but distinct and dense, separated by spaces subequal to diameters of punctures; setae dense, short and nearly recumbent; macrosetae lacking.

Elytra together oval, broadest between middle and anterior third; EL 0.33 mm, EW 0.28 mm, EI 1.18; humeral calli and short, shallow basal impressions distinct; subhumeral lines lacking; narrow area on each elytron along sides of scutellum and in anterior region of suture demarcated from disc by elongate groove; sides of elytra strongly rounded; elytral apices separately rounded. Punctures shallow and small, inconspicuous; setae similar to those on pronotum but slightly shorter and sparser.

Hind wings long and functional.

Legs moderately long and slender, unmodified.

Aedeagus ( Figs 6–7 ) stout, drop-shaped; AeL 0.23 mm; median lobe in ventral view broadest in sub-basal third, gradually narrowing toward subtrapezoidal, truncate apex; diaphragm poorly defined; in lateral view apical region of median lobe narrow and strongly curved dorsad; endophallus with elongate bell-shaped structure in subapical region; parameres slender and in lateral view strongly bent in sub-basal region, each with three short apical and subapical setae.

Female. Unknown.

Distribution. Central Palawan ( Fig. 10 ).

Etymology. The adjective impressus refers to the large and strongly impressed transverse antebasal groove.

Remarks. This species is unique among Cephennomicrus of the Philippines in the densely, finely punctate pronotum with conspicuously deep transverse antebasal groove joining inner pits, and the region between each inner and outer pit narrow and developed as a short longitudinal wrinkle. Moreover, the adscutellar region of each elytron is sharply demarcated from the median basal elytral area by an elongate impression; this is another conspicuous feature, in the Philippines previously known only in C. clypeatus . The latter species, however, has a different body shape, finely punctate pronotum and a strongly elongate, indistinctly delimited and loosely assembled antennal club.

Figures

FIGURE 10. Distribution of nominal Cephennomicrus species within the Philippines, with unique aedeagus illustrated for each species.

FIGURES 1–3. Dorsal habitus of holotype males. Cephennomicrus palawanicus sp. n. (1); C. impressus sp. n. (2); C. lagun- ensis sp. n. (3).

FIGURES 4–9.Aedeagus in ventral (4, 6, 8) and lateral (5, 7, 9) views. Cephennomicrus palawanicus sp. n. (4–5); C. impressus sp. n. (6–7); C. lagunensis sp. n. (8–9).