Pachyserica hoabinhensis Ahrens, Zhao, Pham & Liu, 2024

Ahrens, Dirk, Zhao, Ming-Zhi, Pham, Phu Van & Liu, Wan-Gang, 2024, Taxonomic updates on Pachyserica Brenske, 1898 and Serica MacLeay, 1819 reveal 38 new species and new challenges of Sericini systematics regarding DNA barcodes and genus-level diagnostic key characters (Coleoptera: Scarabaeidae: Sericinae), Zootaxa 5491 (1), pp. 1-89 : 42-43

Pachyserica hoabinhensis Ahrens, Zhao, Pham & Liu , new species

Fig. 17G–N

Type material examined. Holotype ♂ “X-DA6236 / X-DA6236 Vietnam Hoa Binh Prov., Pa Co Hang Kia Nature Reserve 900–1200m leg. L. Bartolozzi, S. Bambi, F. Cianferoni, G. Mazza, E. Orbach (n° Magazz. 2950) 9.– 12.vi.2013? sp.TigerThai132 / Asia Sericini spec. 1348” ( MZUF / VNMN).

Description of holotype. Length: 10.6 mm, length of elytra: 7.6 mm, width: 6.5 mm. Body oval and strongly convex, dark brown, dorsal face with strong greenish, iridescent shine, elytra without dark spots, antenna yellow, dorsal and ventral surface with fine, partly patchily distributed, or dense, short, adpressed, white, or yellowish setae, on head, pronotum and anterior elytra with a few long, fine, erect, yellow setae.

Labroclypeus rectangular, wider than long, widest shortly before base, lateral margins convex and convergent anteriorly and slightly also basally, anterior angles strongly convex; anterior margin straight; margins weakly reflexed; surface flat, moderately shiny, finely and sparsely punctate, with a few long, erect setae; frontoclypeal suture indistinct, not elevated, and weakly curved; smooth area anterior to eye 1.2 times as wide as long; ocular canthus long and narrow (1/3 of ocular diameter), impunctate and with a long terminal seta. Frons flat, with fine and dense punctures, with fine, partly dense, white, adpressed scales beside eyes and with a few yellow, long, erect setae. Eyes small, ratio diameter/interocular width: 0.58. Antenna with ten antennomeres; club with three antennomeres, 1.2 times as long as remaining antennomeres combined and straight. Mentum elevated and anteriorly flattened. Labrum moderately produced medially, distinctly emarginate medially, with only two small and blunt teeth beside emargination.

Pronotum wide and trapezoidal, distinctly wider than long, widest at base, lateral margins slightly concave in basal half, strongly convergent anteriorly, at middle slightly convexly bent, and in anterior half weakly convex and strongly convergent anteriorly; anterior angles not produced, convex, almost obsolete; posterior angles acute; anterior margin straight, with a fine marginal line; surface moderately densely and finely punctate, with widely impunctate patches and midline, surface with sparse, fine, white, short, adpressed scale-like setae and with a few long, yellow, erect setae; anterior and lateral margins with long, dense setae; hypomeron distinctly carinate, carina produced ventrally. Scutellum slender and long, triangular, finely and densely punctate, with short, adpressed scale-like setae as in pronotum, median base widely impunctate and glabrous.

Elytra oval, widest at middle, striae distinctly impressed, finely and densely punctate, intervals convex, almost completely impunctate, some parts with fine, irregularly, and sparse punctures; some patches on intervals with dense, fine, short, white, adpressed setae, intervals on apical declivity and lateral intervals with a few, fine, long, erect setae; epipleural edge robust, ending at moderately curved external apical angle of elytra, epipleura densely setose; apical border narrowly membranous, with a very fine, barely visible membranous rim of fine microtrichomes (magnification 100x).

Ventral surface dull, finely and densely punctate, metasternum and metacoxa with fine and dense, adpressed, white setae, metasternal disc additionally with fine, long setae; metacoxa additionally laterally with few robust setae; abdominal sternites finely and densely punctate, with a transverse row of coarse punctures, each bearing a short, robust seta, otherwise also covered with fine, white, dense setae. Mesosternum between mesocoxae almost as wide as mesofemur. Ratio of length of metepisternum/metacoxa: 1/1.96. Pygidium moderately convex and dull, finely and densely punctate, with wide, smooth midline, with fine, white, dense, short, adpressed scales and sparse, fine, long, erect setae.

Legs moderately slender; femora with two longitudinal rows of setae, coarsely and densely punctate between rows; metafemur iridescent shiny, anterior margin acute, without a continuously serrated line behind anterior margin; ventral posterior margin serrated in apical half and not widened, dorsal posterior margin completely serrated, in basal half with a few long setae which are half as long as width of metafemur. Metatibia moderately slender and long, widest shortly before apex, ratio of width/length: 1/3.7; dorsal margin sharply carinate, with two groups of spines, basal group at middle, apical group at three quarters of metatibial length, basally with a few single, robust setae; lateral face longitudinally concave, along finely and densely punctate, punctures elongate, without longitudinal wrinkles, with sparse, short, white, adpressed setae; ventral margin serrated, with three equidistant, robust setae; medial face sparsely punctate and glabrous; apex interiorly near tarsal articulation concavely truncate. Tarsomeres ventrally with sparse, minute setae, dorsally finely sparsely punctate; metatarsomeres laterally not carinate, smooth, with a strongly serrated ridge ventrally; first metatarsomere as long as following two tarsomeres combined and distinctly longer than dorsal tibial spur. Protibia short, bidentate, external margin smooth; anterior claws symmetrical, basal tooth of inner claw normal.

Aedeagus: Fig. 17I–N . Habitus: Fig. 17G–H .

Diagnosis. Pachyserica hoabinhensis new species differs from P. striatipennis Moser, 1908 by the long and medially extended basal lobe of the left paramere, including its narrow and long apical branch; the basal lobe of the right paramere is almost reduced, very small, narrow and sharp. The right apex of the phallobase is ventrally slightly and convexly produced and provided with a tiny raster.

Etymology. The name of this new species (adjective in nominative case) is derived from its occurrence in the Hoa Binh Province ( Vietnam).

Figures

FIGURE 17. A–F: Pachyserica natmatoung new species (holotype); G–N: P. hoabinhensis new species (holotype); A, I: aedeagus, left side lateral view; D, N: aedeagus, right side lateral view; C, K: parameres, dorsal view; B, J: aedeagus, dorsal view; L: left paramere, 90° dorsal view; M: right paramere, 90° dorsal view; E, H: habitus, dorsal view; F, G: habitus, lateral view. Scale bar: 0.5 mm. Habitus images not to scale.