Tetraserica sraeken Ahrens, 2023

Ahrens, Dirk, Lukic, Daniel, Pham, Phu, Li, Wei & Liu, Wangang, 2023, Tetraserica Ahrens, 2004 of continental Southeast Asia: new records, new species and an updated key to species (Coleoptera: Scarabaeidae: Sericinae: Sericini), Zootaxa 5374 (4), pp. 451-486 : 456-458

Tetraserica sraeken Ahrens , new species

Fig. 2A–E

Type material examined. Holotype: ♂ “Coll. I.R.Sc.N.B. Cambodia, Kampong Speu prov. Phnom Aural W.S., nr. Srae Ken vill. 10–14.v.2018, 200–400m 11°59’N 104°08’E GTI Project, Leg. J. Constant & P. Limbourg, I.G. 33.732/ 1227 Sericini Asia spec.” ( ISNB).

Description of the holotype. Length: 8.4 mm; length of elytra: 5.8 mm; maximum width: 4.9 mm. Dorsal surface dark brown and glabrous, ventral surface including legs reddish brown, antenna yellow.

Labroclypeus subtrapezoidal, wider than long, widest at base, lateral margins moderately convex and convergent to strongly rounded anterior angles, anterior margin weakly emarginate medially, margins moderately reflexed; surface weakly convex, moderately shiny, finely and densely punctate, glabrous; frontoclypeal suture indistinctly incised, flat and weakly curved medially; ocular canthus short and triangular, impunctate, with a single terminal seta. Smooth area anterior to eye 2.5 times as wide as long. Frons dull, with sparse, fine punctures, with two single erect setae beside each eye. Antenna yellowish, with ten antennomeres; club composed of four antennomeres in male, straight, as long as remaining antennomeres combined. Eyes moderately large, ratio of diameter/interocular width: 0.7. Mentum elevated and slightly flattened anteriorly.

Pronotum moderately wide and convex, widest shortly before base, lateral margins evenly convex, strongly narrowed anteriorly towards sharp and slightly produced anterior angles, posterior angles convex. Anterior margin of pronotum slightly convex, with fine, complete marginal line. Surface finely and densely punctate, except minute setae glabrous, lateral and lateral anterior margins sparsely setose. Hypomeron not carinate. Scutellum triangular, including midline finely and densely punctate.

Elytra oblong, widest in posterior third, striae distinctly impressed, finely and moderately densely punctate, intervals weakly convex, with fine and dense punctures concentrated along striae, with very minute setae in punctures and a very few short setae on odd intervals; epipleural edge robust, ending at convex external apical angle of elytra, epipleura densely setose; apical border with a narrow fringe of microtrichomes (100x).

Ventral surface dull, 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. Ratio of length of metepisternum/metacoxa: 1/1.76. Pygidium flat and dull, densely punctate, without smooth midline, almost glabrous, with a few longer setae along apical margin.

Legs wide; femora finely and sparsely punctate; metafemur wide and moderately shiny or dull, anterior margin acute; ventral posterior margin smooth and moderately widened in apical half, dorsal posterior margin smooth, with a few short setae basally. Posterior margin of metafemur straight. Metatibia short and wide, widest at middle; ratio width/length: 1/2.8; basal group of dorsal spines of metatibia at first third, apical one at two thirds of metatibial length; ventral margin weakly convex and serrate, with four equidistant robust setae; apical margin bluntly and slightly concavely truncated towards ventral margin. Tarsomeres dorsally smooth, with fine, sparse setae ventrally, neither laterally nor dorsally carinate; metatarsomeres with a strongly serrated ridge ventrally and glabrous; first metatarsomere as long as following two tarsomeres combined, one quarter of its length longer than dorsal tibial spine. Protibia short, bidentate; anterior claws symmetrical, basal tooth of both claws bluntly truncate at apex.

Aedeagus: Fig. 2A–D . Habitus: Fig. 2E . Female unknown.

Diagnosis. Tetraserica sraeken Ahrens , new species is in shape of aedeagus most similar to Tetraserica nussi Fabrizi, Dalstein & Ahrens, 2019 ( Fig. 2F–N ). Tetraserica sraeken Ahrens , new species differs by the shorter left paramere, as well as by the shorter distal part (which starts with the strong median bent of the paramere; lateral view).

Etymology. The new species is named after its type locality, Srae Ken village (noun in apposition).

Figures

FIGURE 2. A–E: Tetraserica sraeken Ahrens, new species (holotype); F–N: T. nussi Fabrizi, Dalstein & Ahrens, 2019 (variation: F–J, specimen sp1228; K–N, specimen sp1227B). A, F, K: aedeagus, left side, lateral view; B, G: aedeagus, dorsal view; C, H, L: parameres, dorsal view; D, I, M: aedeagus, right side, lateral view; E, J, N: habitus. Scale bars: 0.5 mm. Habitus not to scale.