Mychocerinus caledonicus, Jałoszyński & Ślipiński, 2022

Jałoszyński, Paweł & Ślipiński, Adam, 2022, Revision of the family Murmidiidae (Coleoptera: Coccinelloidea), Zootaxa 5109 (1), pp. 1-102 : 90-92

Mychocerinus caledonicus sp. n.

( Figs 279–285 )

Type material examined. Holotype ( New Caledonia): sex unknown, “ New Caledonia 8667 / 21º07’ Sx 164º57’E / Tiea Reserve, 30m / 4-5Nov2001. C.Burwell & / G.Monteith.Pyr. trees,logs” ( QMB) . Paratypes (24 exx, incl. 1 dissected ♂): 7 exx, same data as for holotype; 16 exx (incl. 1 dissected ♂), “New Caledonia 11505 / 20º37’S x 164º20’E. / Koumac Caves, 50m. / 1Feb2004. G.Monteith. / pyrethrum, trees & logs” ( ANIC, QMB, MNHW); 1 ex., “7 miSE of La Foa / New Caledonia / 20:I:1945”, “Col.&pres.by / C.I.Remington ”, “under bark” ( FMNH) .

Diagnosis. Body short oval, from moderately light to dark brown, uniformly pigmented; dorsal pubescence erect and relatively dense; pronotum strongly narrowing from base; large punctures distributed on sides of pronotal disc, lacking on median region; elytral punctures fine on anteromedian adsutural region but distinct and dense on sides, in some rows separated by spaces subequal to their diameters; lateral longitudinal carinae of mesoventral plate forming an angle of ~20 degree with longitudinal body axis; parameres stout, ~2.5 times as long as broad, with setae distributed from their bases.

Description. BL 0.94–1.13 mm; BL/EW 1.39–1.50. Body short oval ( Figs 279–281 ) and in lateral view weakly convex ( Fig. 282 ), with highest site situated distinctly behind middle of elytra; pigmentation light to dark umbra brown; dorsum covered with short yellowish recumbent and relatively short setae; clypeus with very fine but distinct microreticulation, semi-matt, reticulation on remaining body parts indistinct or lacking.

Head 0.25–0.30 mm wide; frons and vertex weakly convex, distinct punctures distributed mainly on vertex, where they are dense but shallow, separated by spaces subequal to their diameters; clypeus semi-matt; eyes large, strongly convex, coarsely faceted.

Pronotum ( Figs 279‒280 ) strongly transverse, broadest at base; PL 0.20–0.25 mm, PW 0.53–0.63 mm, PL/PW 0.36–0.41; lateral margins nearly straight in posterior half, in anterior region strongly converging anterad; lateral carinae narrow but distinct; anterior pronotal margin lacking marginal line. In most specimens a pair of large, shallow, diffuse and oval submedian impressions is present in posterior half of disc. Punctures on disc uneven, those on large anteromedian area fine and inconspicuous, those on sides much larger, distinct, separated by spaces as wide as 1‒2 their diameters.

Prosternum ( Fig. 281 ) with distinct microreticulation and with fine, inconspicuous setiferous punctures; prosternal carinae about as long as 3/4 of prosternum, indistinctly arcuate, convex mesally; notosternal carinae slightly curved outwards and not reaching anterior prosternal margin, the latter with distinct marginal carina and relatively shallowly emarginate.

Elytra ( Figs 279–280 ) together oval, with strongly rounded sides, broadest distinctly in front of middle, EL 0.68–0.80 mm, EW 0.68–0.80 mm, EL/EW 1.00–1.07. Humerus with distinct callus; elytra densely but finely punc- tate, punctures on large anteromedian adsutural region very small and shallow, partly arranged in longitudinal rows but barely discernible under stereomicroscope, those on side of each elytron distinctly larger and sharply marked, but also shallow, and partly arranged in irregular, not very distinct longitudinal rows, at least some punctures relatively dense, separated by spaces subequal to their diameters, especially in anterior lateral 1/3 of each elytron.

Hind wings fully developed.

Mesoventral plate ( Fig. 283 ) 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 nearly straight.

Metaventrite ( Fig. 283 ) with distinct, dense and numerous punctures on sides; median region with fine, inconspicuous setiferous punctures. Discrimen externally poorly marked.

Aedeagus ( Figs 284–285 ) 0.25 mm long, moderately slender; penis in lateral view weakly curved near basal third; tegmen slender, parallel-sided with relatively stout, subtriangular parameres which are about ~2.5 times as long as broad and each bears 4 long and one short setae distributed from very base to apex.

Distribution. New Caledonia.

Etymology. Topotypical, after New Caledonia.

Remarks. Only M. caledonicus and M. oahuanus have distinctly erect dorsal pubescence, a feature that distinguishes them from all remaining congeners. Although the aedeagi of these two species are similar, the external morphology offers unambiguous features to distinguish them, including a clearly different body outline in dorsal (distinctly elongate in M. caledonicus vs. nearly circular in M. oahuanus ) and lateral view (in M. caledonicus the highest site is shifted toward the hind half of the elytra), and distribution of large punctures on the pronotum, elytra and metaventrite. Mychocerinus caledonicus is variable in body pigmentation, from light to dark brown, but in all studied specimens the pronotum and elytra have the same colour, whereas in M. oahuanus the elytra are distinctly darker than the pronotum. Moreover, in M. caledonicus there is a pair of large, shallow and diffuse submedian impressions on the pronotum, poorly defined only in one or two studied specimens. Mychocerinus oahuanus lacks this feature.

Figures

FIGURES 279–285. Morphological structures of Mychocerinus caledonicus sp. n. Body in dorsal (279–280), ventral (281) and lateral (282) views; pterothorax in ventral view (283); and aedeagus (284–285).