Gastroserica loei Ahrens, Lukic

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 : 23-24

Gastroserica loei Ahrens, Lukic & Liu, new species

Figs. 6J–M , 24

Type material examined. Holotype: Ô “Phu Rua NP (900m alt.), Loei P., NE Thai. 26-30.IV.2006 Takakuwa, M. leg. / 1162 Sericini Asia spec.” ( ZFMK) . Paratypes: 1 Ô, 3 ♀♀ “Phu Rua NP (900m alt.), Loei P., NE Thai. 26- 30.IV.2006 Takakuwa, M. leg.” ( ZFMK) .

Description of holotype. Length: 4.9 mm, length of elytra: 3.2 mm, width: 2.9 mm. Body oval, yellowish brown, antennal club, frons and margins of elytra blackish, dorsal surface shiny, nearly glabrous.

Labroclypeus narrow and almost square, as wide as long, widest at middle, lateral margins convex and weakly convergent to rounded anterior angles; anterior margin moderately emarginated medially, margins weakly reflexed; lateral margins and ocular canthus produce a blunt angle; surface flat, finely and densely punctate, with numerous long, erect setae; frontoclypeal suture finely incised and curved medially. Frons shiny, with dense, fine punctures, beside eyes with a few long setae, otherwise glabrous. Smooth area in front of eyes twice as wide as long. Ocular canthus sparsely finely punctate, narrow and moderately long (1/3 of ocular width), with a terminal seta. Eyes very large, ratio of diameter/interocular width: 0.93. Antenna with ten antennomeres; club composed of four antennomeres, reflexed, 2.2 times as long as remaining antennomeres combined. Mentum elevated and slightly flattened anteriorly.

Pronotum wide, widest at middle, lateral margins evenly convex and convergent to rectangular and moderately produced and almost blunt anterior angles and blunt posterior angles. Anterior margin of pronotum convex, with robust and complete marginal line; basal marginal line absent; surface finely and densely punctate, glabrous; anterior and lateral anterior margins sparsely setose. Hypomeron carinate, weakly produced ventrally. Scutellum triangular, coarsely and densely punctate, on median base impunctate.

Elytra short, widest at middle, striae finely impressed, finely and densely punctate, intervals weakly convex, with fine and sparse punctures concentrated along striae, almost entirely glabrous; 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 shiny, finely and densely punctate, metasternum sparsely covered with fine, short, or very minute setae; metacoxa glabrous, with a few single setae laterally. Mesosternum between mesocoxae as wide as mesofemur. Ratio of length of metepisternum/metacoxa: 1/1.77. Abdominal sternites finely punctate, with a transverse row of coarse punctures, each bearing a robust seta. Pygidium weakly convex and shiny, with fine and moderately dense punctures, without smooth midline, with numerous short setae and a few longer on apical part.

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 finely serrate at apex, only weakly widened in apical half, dorsal posterior margin serrate, with a few short setae basally. Metatibia moderately long and wide, widest at middle, ratio width/ length:1/3.1; dorsal margin sharply carinate, with two groups of spines, basal group at one third, apical one at two thirds of metatibial length, in basal third with a few robust single setae; lateral face longitudinally convex, finely and sparsely punctate, along midline smooth, glabrous; ventral margin 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 impunctate; metatarsomeres in holotype missing. Protibia short, bidentate; anterior claws symmetrical, basal tooth of both claws bluntly truncate at apex.

Aedeagus: Fig. 6J–L . Habitus: Fig. 6M .

Diagnosis. Gastroserica loei Ahrens, Lukic & Liu, new species is in external appearance and shape of aedeagus similar to Gastroserica lucidomarginalis Ahrens, Lukic & Liu, new species and G. ivoi Ahrens, Lukic & Liu, new species Gastroserica loei differs by the very large eyes, the long antennal club, and the (in relation to the phallobase) rather short parameres, while the characteristics of the phallobase are more similar to G. piceocoerulea Ahrens, Lukic & Liu, new species.

Etymology. The name of the new species is named after its occurrence in Loei province (noun in apposition).

Variation. Length: 4.5–5.4 mm, length of elytra: 3.1–3.8 mm, width: 2.6–3.4 mm. Metatarsomeres glabrous, with a strongly serrated ridge ventrally and a parallel subventral smooth carina immediately beside it; first metatarsomere little shorter than following two tarsomeres combined and twice as long as dorsal tibial spur. Female: antennal club short, composed of three antennomeres, little shorter than remaining antennomeres combined; eyes little smaller than in male, ratio of diameter/interocular width: 0.6.

Figures

FIGURE 6. A–D: Gastroserica ivoi Ahrens, Lukic & Liu, new species (holotype); E–I: G. lucidomarginalis Ahrens, Lukic & Liu, new species (holotype); J–M: M. loei Ahrens, Lukic & Liu, new species. A, E, J: Aedeagus, left side lateral view; C, H, L: Aedeagus, right side lateral view; B, F, G, K: Parameres, dorsal view; D, I, M: Habitus (not to scale). Scale: 0.5 mm.

FIGURE 24. Distribution of the genus Gastroserica (Helioserica Ahrens, Lukic & Liu, new subgenus), part 1.