Tetraserica sonla Ahrens, Pacholátko & Pham, 2025

Pham, Phu V., Pacholátko, Petr & Ahrens, Dirk, 2025, New species and records of Tetraserica Ahrens, 2004 from Indochina (Coleoptera: Scarabaeidae: Sericinae), Zootaxa 5691 (2), pp. 193-230 : 202

Tetraserica sonla Ahrens, Pacholátko & Pham , sp. nov.

Fig. 3G–L

Type material examined. Holotype ♂ “VS24-0644 / Vietnam: Son La Pro., Thuan Chau Dist. , Copia NP., UV3, 8.vi.2024, PV Pham leg.” ( IBHV) . Paratypes: 1 ♂ “VS24-0720 / Vietnam: Son La Pro., Thuan Chau Dist. , Copia NP., UV2, 7.vi.2024, PV Pham leg.” ( IBHV) , 1 ♂ “VS24-0802a / Vietnam: Son La Pro., Thuan Chau Dist. , Copia NP., UV1, 6.vi.2024, PV Pham leg.” ( ZFMK) , 1 ♂ “VS24-0802b / Vietnam: Son La Pro., Thuan Chau Dist. , Copia NP., UV1, 6.vi.2024, PV Pham leg.” ( ZFMK) .

Description of holotype. Length: 11.3 mm; length of elytra: 8.1 mm; maximum width: 6.8 mm. Dorsal surface dark brown and glabrous, frons and pronotum with weak greenish shine, labroclypeus, ventral surface and 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 twice 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 small, ratio of diameter/interocular width: 0.65. 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, finely and densely punctate.

Elytra oblong, widest in posterior third, striae distinctly impressed, finely and moderately densely punctate, intervals flat, with fine and almost evenly dense punctures weakly concentrated along striae, with very minute setae in punctures; 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: 1/1.67. Pygidium weakly convex in apical half and dull, densely punctate, without smooth midline, almost glabrous, with numerous longer setae along apical margin.

Legs wide; femora finely and sparsely punctate; metafemur wide and moderately shiny, anterior margin acute, ventral posterior margin smooth and only weakly widened in apical half, with a sharp, sharply pointed tooth at basal third, which is a quarter as long as maximum width of metafemur, dorsal posterior margin smooth and glabrous. Metatibia moderately short and wide, widest at middle; ratio width/length: 1/3.3; basal group of dorsal spines of metatibia at first third, apical one at two thirds of metatibial length; distal margin not truncated, terminal spines of normal length. Tarsomeres dorsally smooth, with fine, dense setae ventrally on distal half, neither laterally nor dorsally carinate; metatarsomeres with a strongly serrated ridge ventrally and glabrous; first metatarsomere little shorter than following two tarsomeres combined, a 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: Fig. 3I–L . Habitus: Fig. 3G, H . Female unknown.

Variation. Length: 9.8–11.3 mm; length of elytra: 6.6–8.1 mm; maximum width: 5.6–6.8 mm.

Diagnosis. Tetraserica sonla Ahrens, Pacholátko & Pham , sp. nov. differs from all other species that share a sharp, tooth-like spine at the ventral posterior margin of metafemur the median lamina of phallobase which is reduced in size and much shorter in size than width of phallobase (in lateral view), being usually not visible. Furthermore, the new species differs by the shape of parameres: the left paramere is composed by a single lobe, while lobes of the right parameres are short and almost of the same length.

Etymology. The name of the new species is derived from its occurrence in Son La Province (noun in apposition).

Figures

FIGURE 3. Holotypes of Tetraserica quangtri Ahrens, Pacholátko & Pham, sp. nov. (A–F) and T. sonla Ahrens, Pacholátko & Pham, sp. nov. (G–L). A, I: aedeagus, left side lateral view; B, J: aedeagus, dorsal view; C, K: parameres, dorsal view; D, L: aedeagus, right side lateral view; E, G: habitus, lateral view; F, H: habitus, dorsal view. Scale: 0.5 mm. Habitus not to scale.