Mychocerinus piceus, Jałoszyński & Ślipiński, 2022

Jałoszyński, Paweł & Ślipiński, Adam, 2022, Revision of the family Murmidiidae (Coleoptera: Coccinelloidea), Zootaxa 5109 (1), pp. 1-102 : 94-96

Mychocerinus piceus sp. n.

( Figs 293–296 )

Type material examined. Holotype ( Argentina): ♀, “ ARG:JujuyProv./ CalileguaNat.Park /18-28.XII.87,S&JPeck / EstacaElCero. 900m / forestmalaise-FIT” ( CMN).

Diagnosis. Body elongate oval, uniformly dark brown, dorsally with silky or oily shine; dorsal pubescence recumbent and relatively dense; pronotum strongly narrowing from base, with almost evenly rounded sides; moderately large but somewhat coarse punctures are present mainly on sides of pronotal disc, median region virtually impunctate; elytral punctures virtually absent on large anteromedian adsutural region but distinct and moderately dense on sides, in longitudinal rows separated by spaces subequal to their diameters; lateral longitudinal carinae of mesoventral plate forming an angle of ~30 degree with longitudinal body axis.

Description. BL 1.15 mm; BL/EW 1.44. Body moderately elongate oval ( Figs 293, 295–296 ) and in lateral view weakly convex ( Fig. 294 ), with highest site situated near middle of elytra; pigmentation dark brown; dorsum covered with short yellowish recumbent and relatively short setae; microreticulation on head, pronotum and elytra extremely fine and dense so that surface is semi-glossy with silky or oily iridescent shine.

Head 0.33 mm wide; frons and vertex weakly convex, entirely covered with distinct punctures separated by spaces subequal to their diameters; clypeus semi-matt; eyes large, strongly convex, coarsely faceted.

Pronotum ( Figs 293, 295 ) strongly transverse, broadest at base; PL 0.28 mm, PW 0.63 mm, PL/PW 0.44; lateral margins almost evenly rounded and strongly converging anterad; lateral carinae narrow but distinct; anterior pronotal margin lacking marginal line. A pair of large, very shallow, diffuse and oval and barely discernible submedian impressions is present in posterior half of disc. Punctures on disc unevenly distributed, moderately large, distinct and somewhat coarse punctures are distributed mainly on sides of disc, leaving large median area almost impunctate, punctures on sides are separated by spaces as wide as 1‒3 their diameters.

Prosternum ( Fig. 296 ) with weak microreticulation and with fine, inconspicuous setiferous punctures; prosternal carinae about as long as 2/3 of prosternum, indistinctly arcuate, slightly convex mesally; notosternal carinae slightly curved outwards and not reaching anterior prosternal margin, the latter lacking marginal carina and relatively shallowly emarginate.

Elytra ( Figs 293, 295 ) together oval, with moderately strongly rounded sides, broadest near anterior third, EL 0.80 mm, EW 0.80 mm, EL/EW 1.00. Humerus with distinct callus; elytral punctures on large anteromedian adsu- tural region very fine and shallow and not arranged in longitudinal rows, those on side of each elytron moderately large, distinct, sharply marked, and partly arranged in irregular, not very distinct longitudinal rows, most punctures relatively dense, separated by spaces as wide as 1‒2 × their diameters.

Hind wings fully developed.

Mesoventral plate ( Fig. 297 ) with lateral longitudinal carinae forming an angle of ~30 degree with longitudinal body axis, and junction with metaventral femoral line is rounded; anterior margin of mesoventral plate straight.

Metaventrite ( Fig. 297 ) with distinct, dense and numerous punctures on sides; median region with fine, inconspicuous setiferous punctures. Discrimen externally not discernible. Etymology. The specific epithet piceus refers to the dark pigmentation of this species.

Distribution. Neotropical: Argentina.

Remarks. Although the holotype is a female, it is nevertheless remarkably different from all remaining species and identification should not pose any problems. Not only the body is conspicuously dark and covered with recumbent vestiture, but also it is dorsally extremely finely microsculptured, so that the semi-glossy surface has a silky or oily, slightly iridescent shine.

Figures

FIGURES 293–297. Morphological structures of Mychocerinus piceus sp. n. Body in dorsal (293, 295), lateral (294) and ventral (296) views; and pterothorax in ventral view (297).