Trichocircus mexicanus, Jałoszyński, 2020

Jałoszyński, Paweł, 2020, First records of Trichocircus Jałoszyński and Protandroconnus Franz in Mexico, with descriptions of two new species (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 4750 (2), pp. 204-210 : 205-206

Trichocircus mexicanus sp. n.

( Figs 1–10 )

Type material. Holotype: Mexico (Veracruz State): ♂, four labels: „Cordoba / Mex. Ver. / Dr.A.Fenyes “ [creamy white, printed], „A. FENYES / Collection“ [yellow, printed], small green star, „ TRICHOCIRCUS / mexicanus m. / P. Jałoszyński, 2019 / HOLOTYPUS “ [red, printed] ( MHNG) . Paratype: ♀, same data as for holotype, with stan- dard yellow printed “ PARATYPUS ” label ( MHNG) .

Diagnosis. Male and female macrophthalmous; antennomeres IX–XI in male of equal width; posterior pronotal margin distinctly shorter than anterior margin; vertexal projection in male weakly elevated, with well-demarcated and rounded sides.

Description. Body of male ( Fig. 1 ) moderately slender, strongly convex, brown with slightly lighter appendages, setae and bristles yellowish; BL 1.01 mm.

Head ( Fig. 3 ) in dorsal view subtriangular, broadest at eyes, HL 0.19 mm, HW 0.23 mm; vertexal projection ( Figs 3–4 ; vp) broader than long, weakly elevated, subtriangular in dorsal view, not reaching posterior margin of vertex, with rounded sides and two posteriorly convergent rows of dense setae on dorsal surface; sides of vertex weakly and evenly convex; frons flattened, with frontal plate ( Figs 3–5 ; fp) closer to the level of antennal insertions than to anterior clypeal margin, with long central tuft of numerous setae. Supraantennal tubercles distinct but weakly elevated and diffuse. Unmodified surfaces of frons and vertex covered with fine, inconspicuous punctures and short, sparse, only slightly suberect setae; sides of vertexal projection asetose. Antennae ( Figs 1 , 6 ) moderately long and slender; AnL 0.40 mm; scape and pedicel elongate, antennomeres III–VIII each moderately transverse, IX strongly enlarged ( Fig. 6 ), slightly longer than broad and only slightly asymmetrical, X strongly transverse, as broad as IX but much shorter, nearly symmetrical, XI as broad as X but distinctly longer, distinctly transverse and asymmetrical.

Pronotum in dorsal view ( Fig. 3 ) elongate, broadest at middle; PL 0.28 mm, PW 0.25 mm; anterior margin indistinctly concave, sides evenly rounded, posterior margin nearly straight and conspicuously shorter than anterior margin. Punctures on pronotal disc fine and inconspicuous, setae sparse, longer than those on head and more erect, lateral bristles especially long and dense, suberect and erect.

Elytra ( Figs 1, 3 ) together oval, EL 0.55 mm, EW 0.43 mm, EI 1.29; broadest indistinctly behind middle, with weakly marked, elongate humeral calli, covered with punctures as fine and inconspicuous as those on pronotum; setae sparse, distinctly longer and more erect than those on pronotal disc.

Wings absent.

Legs slender, unmodified.

Aedeagus ( Figs 7–10 ) elongate, AeL 0.10; median lobe in ventral view oval and broadest in basal half, in lateral view with apical portion rapidly bent dorsad and sinuate, endophallus with a long tubular structure at middle; parameres short, each with one long and thick apical seta.

Female. Externally similar to male ( Fig. 2 ) but with antennomeres IX and X of subequal length, unmodified head (i.e., lacking frontal plate and vertexal projection), and distinctly smaller (but still relatively large and strongly convex) eyes. BL 0.98 mm; HL 0.15 mm, HW 0.18 mm, AnL 0.38 mm; PL 0.30 mm, PW 0.28 mm; EL 0.53 mm, EW 0.43 mm, EI 1.24.

Distribution. Southern Mexico.

Etymology. After the country name.

Remarks. The remaining species of Trichocircus have the antennomere XI strikingly small, much narrower than X and even more than IX; in T. mexicanus antennomeres IX–XI have equal widths. Further differences can be found in the shape of the pronotum and the vertexal projection of male. Aedeagi, however, in all known species are surprisingly uniform (one of very few exceptions among Glandulariini), and in Trichocircus external structures are more important for species identification than the male genitalia.

Figures

FIGURES 1–3. Trichocircus mexicanus sp. n. Dorsal habitus of male (1) and female (2); head, prothorax and elytral base of male in dorsal view (3). Abbreviations: fp, frontal plate; vp, vertexal projection.

FIGURES 4–10. Trichocircus mexicanus sp. n., male. Cephalic modifications in anterodorsal view (4, 5), left antennal club in dorsal view (6), aedeagus in ventral (7, 9) and lateral (8, 10) views. Abbreviations: fp, frontal plate; vp, vertexal projection.