Microserica avicula (Arrow, 1946) Ahrens & Liu & Lukic & Bai, 2023

Ahrens, Dirk, Liu, Wangang, Lukic, Daniel & Bai, Ming, 2023, A taxonomic review of Microserica Brenske, 1894 from continental Asia (Coleoptera: Scarabaeidae: Melolonthinae: Sericini), Zootaxa 5241 (1), pp. 1-115 : 37-38

Microserica avicula (Arrow, 1946) new combination

Figs. 13A–D , 28

Aserica avicula Arrow, 1946: 267 .

Type material examined. Holotype Ô [ Vietnam] “Hoa-Binh Tonkin A. de Cooman B.M. 1934-95” ( BMNH) . Additional material examined. 1 Ô, 1 ♀ [ Vietnam] “Museum Paris Tonkin Reg. de Hoa-Binh A. de Cooman 1929 / Museum Paris ex. Coll. R. Oberthür 1952 / 1115 Asia Sericini spec.” ( MNHN) .

Redescription. Length: 5.0 mm, length of elytra: 3.9 mm, width: 3.5 mm. Body oval, body yellowish brown, lateral intervals, frons, two large, pairs of spots on pronotum, and multiple dots on elytra brown, dorsal surface dull and nearly glabrous.

Labroclypeus trapezoidal, wider than long, widest at base, lateral margins almost straight and convergent to moderately rounded anterior angles; anterior margin weakly emarginate medially, margins weakly reflexed; lateral margins and ocular canthus produce an indistinct, blunt angle; surface shiny, medially weakly convex, finely and coarsely, densely punctate, with a few long, erect setae anteriorly in transversal row; frontoclypeal suture finely incised and bent medially. Frons dull, with dense, fine punctures, beside eyes with a few single short setae, otherwise glabrous. Smooth area in front of eyes twice as wide as long. Ocular canthus impunctate, narrow and short (1/4 of ocular width), with a terminal seta. Eyes small, ratio of diameter/interocular width: 0.56. Antenna with ten antennomeres; club composed of four antennomeres, straight, 1.2 times as long as remaining antennomeres combined. Mentum elevated and slightly flattened anteriorly.

Pronotum wide, widest at base, lateral margins weakly evenly convex and convergent to distinctly produced and sharp anterior angles, posterior angles strongly rounded.Anterior margin of pronotum convex, with fine and complete marginal line; basal marginal line absent; surface finely and densely punctate, with minute setae in punctures, anterior and lateral anterior margins sparsely setose. Hypomeron indistinctly carinate, carina not produced ventrally. Scutellum triangular, finely and densely punctate, on midline impunctate.

Elytra short oval, widest at middle, striae distinctly impressed, finely and densely punctate, intervals convex, with fine and sparse punctures concentrated along striae, with very minute setae in punctures, odd lateral intervals with a few short setae; with two incomplete bands of spots on elytra, one anterior with spots on interval 2, 4, and 6, and one posterior behind the middle on intervals 2, 4 to 6; epipleural edge robust, ending at slightly rounded external apical angle of elytra, epipleura densely setose; apical border chitinous, without a fringe of short microtrichomes (visible at ca 100x magnification).

Ventral surface dull, finely and densely punctate, metasternum sparsely covered with fine, short, or very minute setae; metacoxa glabrous, laterally with numerous long, yellow, and robust setae. Mesosternum between mesocoxae as wide as mesofemur. Ratio of length of metepisternum/metacoxa: 1/1.76. Abdominal sternites finely punctate, with a transverse row of coarse punctures, each bearing a robust seta. Pygidium strongly convex and dull, with mixed finer and larger punctures, without smooth midline, with minute setae in punctures and numerous short setae along apical margin.

Legs moderately wide; femora finely and sparsely punctate, with two longitudinal rows of longer setae. Metafemur moderately shiny, anterior margin acute, without submarginal serrated line; anterior row of seta-bearing punctures present; ventral posterior margin weakly widened in apical half, smooth, dorsal posterior margin also smooth, with a few short setae basally. Metatibia moderately long and wide, widest at middle, ratio width/length: 1/2.75; dorsal margin longitudinally convex, with two groups of spines, basal group at first third, apical one at three quarter of metatibial length, basally almost glabrous; lateral face strongly longitudinally convex, finely and sparsely punctate, partly with minute setae in punctures; ventral margin carinate and finely serrate, with three robust equidistant setae; medial face smooth, apex interiorly near tarsal articulation sharply truncate. Tarsomeres with fine, sparse setae ventrally, neither laterally nor dorsally carinate, dorsally smooth; metatarsomeres glabrous, with a strongly serrated ridge ventrally and a parallel subventral smooth carina immediately beside it; first metatarsomere as long as following two tarsomeres combined, almost twice as long as dorsal tibial spur. Protibia short, bidentate; anterior claws symmetrical, basal tooth of both claws bluntly truncate at apex.

Aedeagus: Fig. 13A–C . Habitus: Fig. 13D .

Variation. Female: antennal club short, distinctly shorter than the remaining antennomeres combined, composed of three antennomeres; pygidium flat.

Figures

FIGURE 13. A–D: Microserica avicula Arrow, 1946 (Vietnam: Hoa-Binh); E–H: M. paravicula Ahrens, Lukic & Liu, new species (holotype); I–L: Mic. caiyangana Ahrens, Lukic & Liu, new species (holotype).A, E, I: Aedeagus, left side lateral view; C, G, K: Aedeagus, right side lateral view; B, F, J: Parameres, dorsal view; D, H, L: Habitus (not to scale). Scale: 0.5 mm.

FIGURE 28. Distribution of the Microserica avicula group.