Mychocerinus arizonensis Lawrence & Stephan

Jałoszyński, Paweł & Ślipiński, Adam, 2022, Revision of the family Murmidiidae (Coleoptera: Coccinelloidea), Zootaxa 5109 (1), pp. 1-102 : 88-90

Mychocerinus arizonensis Lawrence & Stephan

( Figs 272–278 )

Mychocerus arizonensis Lawrence & Stephan, 1975: 144 .

Type material examined. Holotype ( USA): “ Arizona, Pima / Co. Arivaca / Dec. 21 1969 / K. Stephan leg.” ( MCZ)

Emended diagnosis. Body elongate oval, moderately light brown, uniformly pigmented; dorsal pubescence recumbent and relatively sparse; pronotum parallel-sided in posterior half and anteriorly strongly, almost abruptly narrowed; large punctures distributed on median region of pronotal disc, lacking on sides; elytral punctures fine and sparse, but 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 slender, nearly 3 times as long as broad, with setae distributed from their proximal 1/3 to apex.

Redescription. BL 1.09 mm; BL/EW 1.58. Body moderately elongate oval ( Figs 272–273 ) and in lateral view weakly convex ( Fig. 275 ), with highest site situated near middle of elytra; pigmentation moderately light brown; dorsum covered with short yellowish recumbent and relatively short setae; head and pronotum with fine but distinct microreticulation but glossy, reticulation on elytra present but superficial and indistinct.

Head ( Fig. 274 ) 0.30 mm wide; frons and vertex weakly convex, with fine, inconspicuous punctures; clypeus semi-matt; eyes large, strongly convex, coarsely faceted.

Pronotum ( Fig. 272 ) strongly transverse, equally wide in posterior half; PL 0.27 mm, PW 0.54 mm, PL/PW 0.50; lateral margins straight and parallel in posterior half, in anterior region strongly converging anterad; lateral carinae narrow but distinct; anterior pronotal margin lacking marginal line. Punctures on disc uneven, those on large anteromedian area large and distinct, separated by spaces as wide as 2‒3 their diameters, those on sides much finer and inconspicuous.

Prosternum ( Fig. 273 ) with distinct microreticulation and with fine, inconspicuous setiferous punctures; prosternal carinae about as long as 2/3 of prosternum, indistinctly arcuate, convex mesally; notosternal carinae slightly curved outwards and not reaching anterior prosternal margin, the latter with indistinct marginal carina and relatively deeply emarginate.

Elytra ( Fig. 272 ) together oval, with moderately strongly rounded sides, broadest near anterior third, EL 0.72 mm, EW 0.69 mm, EL/EW 1.04. Humerus with distinct callus; elytra densely but very finely punctate, punctures on large anteromedian adsutural region indistinct, those on side of each elytron small but sharply marked and partly arranged in irregular, not very distinct longitudinal rows, at least some punctures relatively dense, separated by spaces subequal to their diameters.

Hind wings fully developed.

Mesoventral plate ( Fig. 276 ) with lateral longitudinal carinae forming an angle of ~20 degree with longitudinal body axis, so that junction with metaventral femoral line is distinctly angulate; anterior margin of mesoventral plate nearly straight.

Metaventrite ( Fig. 276 ) with distinct, dense and numerous punctures on sides; median region with fine, inconspicuous setiferous punctures. Discrimen externally well marked.

Aedeagus ( Figs 277–278 ) moderately slender; penis in lateral view weakly bent near distal third; tegmen slen- der, parallel-sided with slender, subtriangular parameres which are about 3 times as long as broad and each bears 4 long setae distributed from proximal third to apex.

Distribution. Nearctic: USA (Arizona), Mexico (Sonora).

Remarks. The body length for this species given in the original description is 1.1‒1.3 mm; we give measure- ments of the holotype only, as no other specimens were examined. This species can be easily identified solely on the basis of its unique pronotal shape, this is the only known Mychocerinus species with the lateral pronotal margins not converging anterad from the very base, but only in the anterior half or less.

The type series was collected from under bark of mesquite (Prosopis sp.) and oaks (Quercus sp.). It is interesting to note that also specimens of another murmidiid, Murmidius hawaiianus , were found under bark of a Prosopis species.

Figures

FIGURES 272–278. Morphological structures of Mychocerinus arizonensis Lawrence & Stephan. Body in dorsal (272), ven- tral (273) and lateral (275) views; head in anterior view (274); pterothorax in ventral view (276); and aedeagus (268–278; after Lawrence & Stephan (1975). 271–275: ©President and Fellows of Harvard College.