Hlavaciellus primitivus, Jałoszyński, 2017

Jałoszyński, Paweł, 2017, Ant-like stone beetles on the roof of the world. Cephenniini of Nepal and Bhutan (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4349 (1), pp. 1-120 : 11-12

Hlavaciellus primitivus sp. n.

( Figs 14–16 , 18 )

Type material. Holotype: NEPAL (Mustang District): ♂, " NEPAL Mustang / Distr. 2km N Ka- / lopani 2550m 1.X. / 83 Smetana & Löbl" [white, printed] ( MHNG). Paratype: ♂, same data as for holotype ( MHNG).

Diagnosis. Antennae very short, not reaching half BL, slender in proximal half and distinctly thickened apically, antennomere XI longer than IX and X combined; aedeagus in lateral view with apex of median lobe forming slightly recurved projection distant from base of apical projection, parameres not curved apically, each with only one thickened apical seta.

Description. Body of male ( Fig. 14 ) elongate, with shallow constriction between pronotum and elytra, strongly convex, dark reddish-brown, covered with vestiture slightly lighter than cuticle; BL 1.50–1.70 mm.

Head subtrapezoidal, HL 0.18–0.23 mm, HW 0.38–0.40 mm; vertex and frons confluent, evenly convex, supraantennal tubercles distinct; eyes large, strongly convex and coarsely faceted. Punctures on vertex and frons distinct, small but sharply marked and deep, separated by spaces shorter than diameters of punctures, only median area on clypeus impunctate or nearly so; setae very short, sparse, recumbent. Antennae short, AnL 0.70–0.78 mm, slender proximally and strongly thickened distally; antennomeres I–III elongate, IV–VII about as long as broad, VII distinctly broader than VI, antennomeres VIII–X strongly transverse, XI nearly as long as VIII–X combined, slightly more than twice as long as broad, narrowing nearly from base.

Pronotum in dorsal view subtrapezoidal with rounded anterior margin; PL 0.50–0.55 mm, PW 0.60–0.68 mm; sides weakly rounded in anterior half and nearly parallel in posterior half; posterior margin weakly bisinuate; posterior corners nearly right-angled; basal pits shallow but large, the deepest site of each pit located distinctly closer to lateral than to posterior pronotal margin; lateral margins with narrow carina in posterior third. Punctures on median portion of pronotal disc distinctly smaller, shallower and slightly sparser than those on frons and vertex but still distinct, separated by spaces 1–1.5 × as wide as diameters of punctures; setae short, sparse, suberect.

Elytra oval, broadest distinctly in front of middle, EL 0.83–0.93 mm, EW 0.70–0.78 mm, EI 1.18–1.19. Humeral calli small but distinct, mesally delimited by very shallow and short impression; basal elytral fovea located much closer to the lateral margin of mesoscutellum than to humerus; apices of elytra separately rounded. Punctures on elytra slightly larger than those on pronotum but superficial and with diffuse margins, separated by spaces equal to or slightly shorter than diameters of punctures; setae short, moderately dense, suberect.

Hind wings present, long.

Protibiae distinctly thicker than meso- and metatibiae.

Aedeagus ( Figs 15–16 ) elongate and slender, AeL 0.43 mm, median lobe with proximal bulbous part bearing distinctly demarcated membranous ventrodistal diaphragm and well-defined apex that in lateral view forms a slightly recurved projection distant from bases of apical projection; the latter asymmetrical, apical region of dorsal wall forming slender subtriangular projection with its apical portion curved ventrally; parameres slender, each bearing one very thick apical seta curved ventrally.

Female. Unknown.

Distribution ( Fig. 18 ). Central Nepal.

Etymology. The specific epithet primitivus refers to the unusual aedeagus of this species, which shows apparently plesiomorphic structures.

Remarks. This is a very unusual species of Hlavaciellus that may deserve placement in a separate subgenus. All remaining species of this genus have conspicuously long and massive antennae, which are longer (typically much longer) than half BL (and in some cases as long as BL) and gradually thickened from base; they also have slender, strongly elongate aedeagi with the apex of the ventral wall touching the ventral surface of apical projection, parameres strongly curved dorsally in the apical region, and each always bearing two conspicuously thick and long subapical setae distant from the parameral apex. Only in H. sabahensis Stevanović, 2009 (Borneo) each paramere bears a thickened apical seta in addition to two subapical ones. In H. primitivus , the aedeagus shows structures intermediary between Hlavaciellus and its sister group, Cephennodes ; the median lobe is relatively short, has a well-defined ventrodistal diaphragm and distinct apex, which in lateral view is separated from the base of apical projection; and the parameres are not strongly thickened and curved apically, but relatively slender and each bears only one seta at the apex. Moreover, the general appearance of H. primitivus resembles more that of most species of Cephennodes , especially the short and rapidly thickened antennae are unlike those in any previously known Hlavaciellus species. The ventral characters, however, clearly place this species in Hlavaciellus .

Figures

FIGURES 14 – 16. Dorsal habitus (14) and aedeagus in ventral (15) and lateral (16) views of Hlavaciellus primitivus sp. n.

FIGURES 17 – 18. Distribution of Cephennomicrus arunensis sp. n. (17, circle), Cm. acupunctatus sp. n. (17, circle), Cm. taplejungensis sp. n. (17, triangle) and Hlavaciellus primitivus sp. n. (18, circle).