Tetraserica Ahrens, 2004

Fabrizi, Silvia, Dalstein, Vivian & Ahrens, Dirk, 2019, A monograph on the genus Tetraserica from the Indochinese region (Coleoptera, Scarabaeidae, Sericini), ZooKeys 837, pp. 1-155 : 3-14

Tetraserica Ahrens, 2004

Tetraserica Ahrens, 2004: 168 (type species by original designation: Neoserica gestroi Brenske, 1898); Liu et al. 2014: 83; Ahrens and Fabrizi 2016: 122; Kobayashi 2017: 33, 2018: 57.

Diagnosis.

Body moderately large to large (6-12 mm), mostly dark brown; ventral surface reddish brown; dorsal surface dull and glabrous.

Labroclypeus subtrapezoidal, wider than long, widest at base, lateral margins moderately convex and convergent to strongly rounded anterior angles, anterior margin weakly sinuate medially, margins moderately reflexed; surface weakly convex, moderately shiny, finely and densely punctate; frontoclypeal suture indistinctly incised, flat and weakly curved medially; ocular canthus short and triangular, impunctate, with a single terminal seta. Frons dull, with sparse, fine punctures, with single erect setae beside each eye. Antenna yellowish, with ten antennomeres; club composed of four antennomeres in male, straight, rarely longer than 1.5 times as the remaining antennomeres combined; club in female composed of three antennomeres, as long as the remaining antennomeres combined. Mentum elevated and slightly flattened anteriorly.

Pronotum moderately wide and strongly convex, lateral margins evenly convex, more strongly narrowed anteriorly towards sharp and slightly produced anterior angles. Anterior margin of pronotum slightly convex, with fine complete marginal line. Posterior angles blunt or strongly rounded. Surface finely and densely punctate, except minute setae glabrous, lateral and lateral anterior margins sparsely setose. Hypomeron not carinate. Scutellum triangular, finely and densely punctate.

Elytra oblong, widest just behind middle, striae distinctly impressed, finely and moderately densely punctate, intervals distinctly convex, with coarse and dense punctures concentrated along striae, with very minute setae in punctures; epipleural edge robust, ending at weakly curved and slightly blunt external apical angle of elytra, epipleura densely setose, apical border with a broad fringe of microtrichomes (100 ×).

Ventral surface weakly shiny, finely and densely punctate, metasternum sparsely covered with fine, short, or very minute setae, metacoxa glabrous, with a few single setae laterally; abdominal sternites finely and densely punctuate, with a transverse row of coarse punctures, each bearing a robust seta. Mesosternum between mesocoxae as wide as mesofemur. Pygidium weakly convex and dull, densely punctate, without smooth midline, almost glabrous, but with a few longer setae along apical margin; pygidium without strong sexual dimorphism.

Legs moderately wide; femora finely and sparsely punctate; metafemur wide and moderately shiny or dull, anterior margin acute, posterior margin smooth ventrally and only weakly widened in apical half, posterior margin smooth dorsally, with a few short setae basally. Posterior margin of metafemur generally straight or slightly convex. Metatibia moderately wide to wide and moderately long, widest at half of metatibial length, dorsal margin sharply carinate, with two groups of spines; lateral face finely and sparsely punctate; ventral edge finely serrated, with four robust equidistant setae, medial face smooth, apex interiorly near tarsal articulation with a shallow sinuation. Tarsomeres with fine, very dense setae ventrally on distal half, neither laterally nor dorsally carinate, dorsally smooth; metatarsomeres with a strongly serrated ridge ventrally and glabrous; first metatarsomere slightly shorter than two following tarsomeres combined, one third of its length longer than dorsal tibial spine. Protibia short, bidentate; anterior claws symmetrical, basal tooth of both claws bluntly truncate at apex.

Aedeagus: Phallobase with a more or less long median ventral extension (median phallobasal lamina).

Remarks.

Tetraserica differs from closely related genera, Microserica Brenske, 1894 and Trioserica Moser, 1922, by lacking the ventral carina on hypomeron. From Microserica it also differs by lacking the sexual dimorphism of the pygidium, from Trioserica by the bidentate protibia. In contrast to the Microserica , species of Tetraserica are active at night and are attracted by light.

Distribution.

The genus is distributed almost in the entire Oriental region except the southern Indian subcontinent; we know that additional species described by various authors are so far assigned to " Neoserica " from Philippines, Sumatra, and Borneo but that awaits a formal revision ( Ahrens 2004).

Key to Indochinese species of Tetraserica Ahrens, 2004 (based on males):

Descriptions