Cephennomicrus perexiguus (Scott)

Jałoszyński, Paweł, 2019, Review of Cephennomicrus and Pomphopsilla of the Seychelles (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4568 (2), pp. 357-371 : 362-364

Cephennomicrus perexiguus (Scott)

( Figs 4 , 20–21, 32–33, 41)

Neseuthia perexigua Scott, 1922: 205 , pl. 19, fig. 5, 5a.

Cephennomicrus perexiguus (Scott) ; Jałoszyński, 2008: 33.

Type material. Lectotype (here designated; labels in Fig. 41 ): ♂, mounted on modern cardboard, but with original thick cardboard placed on the same pin, bearing a male symbol and number 112, with eight labels: " Percy Sladen / Trust Exped. / Brit.Mus. / 1926-246" [white, printed], "Mahe, '08-9 / Seychelles Exp." [white, printed], " Neseuthia / perexigua / TYPE ♂ / H.Scott / TYPE " [white, handwritten, with " TYPE " printed on a piece of blue paper and glued onto the white label], " perexiguus Scott / Cl. Besuchet / dét. X 1957 " [white, printed and handwritten], "Figured specimen / on right hand side" [red, printed and handwritten], "Type" [white circle with red margin, printed], " NESEUTHIA / perexigua / Scott, 1922 / LECTOTYPE / P. JAŁOSZYŃSKI, 2019" [white, printed], and " CEPHENNOMICRUS / perexiguus / (Scott, 2019) / det. P. JAŁOSZYŃSKI, 2019" [white, printed] ( NHM).

Revised diagnosis. BL <0.7 mm; head only with an indistinct punctate and setose frontal flattening, lacking elevations and posterior impressions; aedeagus with long, subtrapezoidal ventral apical plate and narrowly rounded apex, flagellum in ventral view straight, lacking loops.

Redescription. Body of male ( Fig. 4 ) moderately stout, strongly convex, light brown; setae on head, pronotum and elytra very short but well-visible. BL 0.65 mm.

Head broadest at large, strongly convex and coarsely faceted eyes, HL 0.08 mm, HW 0.18 mm; frons with barely discernible median flattening, lacking elevations, vertex confluent with frons, lacking impressions. Punctures on frontal flattening distinct and dense, on remaining areas of frons and on vertex indistinct, moderately dense, very small; setae on frontal impression moderately dense, short and suberect, setae on remaining areas of frons and on vertex sparse, short and recumbent. Antennae slender, with indistinctly delimited trimerous club, AnL 0.30 mm, antennomeres I–II strongly elongate, III–IX each about as long as broad, X indistinctly transverse, XI about as long as IX–X combined, about 1.6 × as long as broad.

Pronotum subtrapezoidal, broadest near anterior fourth; PL 0.20 mm, PW 0.24 mm; anterior and posterior margins weakly convex, sides rounded in anterior third and barely noticeably sinuate in posterior third; anterior corners broadly rounded, posterior corners strongly obtuse-angled and blunt; base with two lateral pairs of small but distinct pits, inner pair connected by a shallow transverse groove, additionally with a very small, barely noticeable median pit; lateral pronotal carinae not serrate. Punctures on pronotal disc dense but superficial and diffuse; setae short, moderately dense, recumbent.

Elytra oval, broadest near anterior third; EL 0.38 mm, EW 0.30 mm, EI 1.25; humeral calli distinct; triangular adscutellar area abruptly elevated. Punctures on elytra similar to those on pronotum but deeper and elytral surface appears very finely shagreened; setae short, moderately dense, recumbent.

Legs moderately long and slender, unmodified.

Aedeagus (Figs 20–21) stout; AeL 0.14 mm; median lobe in ventral view with subtrapezoidal, strongly elongate apical plate; flagellum (Figs 32–33) in ventral view straight, lacking loops; apical and subapical parameral setae equally thin.

Female. Not studied.

Distribution. Seychelles, Mahé island.

Remarks. Scott (1922) mentioned one male and one female, only the male was available for my study. The lectotype was remounted on a modern card, presumably by Claude Besuchet, but the original thick mounting cardboard is placed under the specimen on the same pin.

Males of this species are unique within the typicus group in being very small and having only a barely discernible punctate and setose flattening on the frons, lacking any elevations and impressions; they can be confused with females. Interestingly, the weakly expressed external sexual characters correspond with a short flagellum lacking any loops.

Figures

FIGURES 1–7. Habitus of Cephennomicrus cordithorax (1), C. cornutus (2), C. minor (3), C. perexiguus (4), C. politus (5), C. typicus (6), and Pomphopsilla crenata (7).

FIGURES 38–44. Historical (Scott's and Besuchet's) set of labels of holotypes (38, 39, 42) and lectotypes (40, 41, 43, 44). Neseuthia cordithorax (38), N. cornuta (39), N. minor (40), N. perexigua (41), N. polita (42), N. typica (43), and N. crenata (44).