Murmidius okinawanus, Jałoszyński & Ślipiński, 2022

Jałoszyński, Paweł & Ślipiński, Adam, 2022, Revision of the family Murmidiidae (Coleoptera: Coccinelloidea), Zootaxa 5109 (1), pp. 1-102 : 54-56

Murmidius okinawanus sp. n.

( Figs 156–162 )

Type material examined. Holotype (Japan: Ryukyus ): ♂, “ JAPAN, OKINAWA Island / Nago City, Nago Castle Site / ~ 100 m, 15.02.2019 / humid forest / leg. P. JAŁOSZYŃSKI” ( NSMT) . Paratypes: 3 exx of unknown sex, same data as for holotype (cPJ, MNHW) .

Diagnosis. Body elongate oval and weakly convex, pitchy black; antennal club only slightly elongate; anterior clypeal margin smooth; pronotum lacking lateral and sublateral longitudinal impressions; clypeus with extremely fine microreticulation, frons and vertex with indistinct, superficial traces of microreticulation, elytra lacking microsculpture; elytra with strong and dense punctures not arranged in rows; prosternal carinae only as long as about fourth of prosternum; mesoventral plate with evenly rounded anterior margin and complete but fine submarginal carina, lacking lateral carinae; elytral epipleura strongly narrowed at the level of metaventrite where they are only as wide as half width of mesofemur; metaventrite with large, circular, unevenly distributed punctures on sides; penis stout, in lateral view distinctly curved; in ventral view tapering from near middle to subtriangular and blunt apex; tegmen short and broad, with rounded apex bearing one pair of moderately long and several pairs of short setae.

Description. BL 1.28–1.50 mm; BL/EW 1.45–1.62. Body elongate oval ( Figs 156–157 ) and in lateral view weakly convex ( Fig. 159 ); pigmentation nearly black, in some specimens head and pronotum indistinctly lighter, legs only slightly lighter than; dorsum covered with extremely short whitish setae (discernible under magnification 80 ×); cuticle glossy, on clypeus distinctly but very finely microreticulate, superficial traces of reticulation can also be seen on frons, vertex and, even less distinct, on pronotum.

Head 0.35–0.39 mm wide; frons and vertex weakly convex, with fine but distinct and dense punctures separated by spaces subequal to their diameters; clypeus less glossy than frons; eyes large, strongly convex, coarsely faceted. Antennal club only slightly elongate ( Fig. 157 ).

Pronotum ( Figs 156–157 ) strongly transverse, widest at base; PL 0.25–0.30 mm, PW 0.63–0.70 mm, PL/PW 0.37–0.43; lateral margins weakly rounded and moderately strongly convergent anterad, with narrow lateral carinae; mesal corners of antennal cavities weakly projecting anterad; lateral and sublateral longitudinal impressions lacking; anterior pronotal margin with complete marginal line. Punctures on disc similar to those on frons and vertex but indistinctly larger and sparser, nearly evenly distributed, large punctures lacking.

Prosternum ( Fig. 158 ) with barely discernible transverse microreticulation and with fine, inconspicuous setiferous punctures; prosternal carinae short, about as long as 1/4 of prosternum; notosternal carinae nearly straight and nearly reaching anterior prosternal margin, the latter with distinct narrow marginal carina.

Elytra ( Figs 156–157 ) together oval, with strongly rounded sides, broadest distinctly in front of middle, EL 0.95–1.13 mm, EW 0.88–0.95 mm, EL/EW 1.09–1.22. Humerus with distinct callus; elytra densely punctate, punc- tures small but distinct, not arranged in rows, those on anteromedian region of each elytron almost coarse, separated by spaces slightly shorter than their diameters, punctures reducing in diameter and depth toward sides and apices. Epipleura conspicuously narrowed near middle ( Fig. 160 , arrowhead), so that lateral elytral margin is concave.

Hind wings fully developed.

Mesoventral plate ( Fig. 160 ) lacking lateral longitudinal carinae; anterior margin evenly, broadly rounded, with fine, complete submarginal carina.

Metaventrite ( Fig. 160 ) with large, circular and distinct punctures unevenly distributed on sides; median region with fine, inconspicuous setiferous punctures. Discrimen externally well-marked.

Tarsi with short, inconspicuous setae on tarsomeres 1–3.

Aedeagus ( Figs 161–162 ) 0.35 mm long, stout; penis in ventral view gradually tapering from near middle toward subtriangular, blunt apex, in lateral view distinctly curved; tegmen stout, with rounded apex bearing one pair of moderately long setae and several pairs of much shorter ones.

Distribution. Sub-Oriental (Okinawa-jima).

Etymology. Named after the island of Okinawa.

Remarks. This nearly black species is unique among all members of Murmidius in having the elytral epipleura strongly narrowed near middle, so that the lateral elytral edge is concave between meso- and metacoxae and the epipleuron in its narrowest site in this region is only half as wide as mesofemur. The dark pigmentation and body shape make M. okinawanus similar to M. hebrus and M. merkli ; but the aedeagi, and especially the apical setation of the tegmen, are clearly different in each of them.

The type series of this species was collected by sifting moist leaf litter and rotten wood in subtropical forest.

Figures

FIGURES 156–162. Morphological structures of Murmidius okinawanus sp. n. Body in dorsal (156–157), ventral (158) and lateral (159) views; pterothorax in ventral view (160); and aedeagus (161–162).