Pachyserica dieuthuyae 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 : 44-45

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

Fig. 18A–F

Type material examined. Holotype ♂ “VS0999 Vietnam Ha Giang Pro., Dong Van Dist., Hoa Da guest house 25–31.v.2023 23°12′37.31″N, 105°15′49.26″E T.D. Dinh Pachyserica spVi18 / Asia Sericini 1357 spec.” ( IEBR) . Paratype: 1 ♂ “VS1071 Vietnam Ha Giang Pro., Pho Bang 11–17.vi.2023 T.D. Dinh Pachyserica ? spVi31” ( ZFMK) .

Description of holotype. Length: 8.8 mm, length of elytra: 5.3 mm, width: 5.6 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 or scales, 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, base dull, 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 dense, yellow, long, erect setae. Eyes small, ratio diameter/interocular width: 0.54. 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 straight and convergent in basal half, 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, some patches and midline impunctate, 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, irregularly punctate, partly almost completely impunctate, some parts with fine, irregularly, and sparse punctures; some patches on intervals with dense, fine, short, white, adpressed setae, patches may form several transverse bands, odd 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, scale-like 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: 1/1.76. Pygidium flat and dull, finely and densely punctate, with wide, smooth midline, with fine, white, dense, short, adpressed scales and moderately dense, 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: 1/3.8; 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. 18A–D . Habitus: Fig. 18E, F . Female unknown.

Diagnosis. Pachyserica dieuthuyae new species differs from the in shape of aedeagus similar P. balkei Ahrens, 2006 by the apical phallobase whose margin towards the mesal emarignation is not elevated and reflexed, by the left paramere being almost straight (dorsal view), and by the narrower right paramere. Furthermore, the parameres are straight in lateral view in the new species, while in P. balkei they are slightlyy curved ventrally.

Etymology. This new species is named after Ms. Dinh Dieu Thuy who collected the examined specimens.

Variation. Length: 8.8–9.5 mm, length of elytra: 5.3–6.9 mm, width: 5.6–5.8 mm.

Figures

FIGURE 18. A–F: Pachyserica dieuthuyae new species (holotype); G–K: P. chenchangchini new species (holotype); A, I: aedeagus, left side lateral view; D, K: aedeagus, right side lateral view; C, J: parameres, dorsal view; B: aedeagus, dorsal view; E, G: habitus, dorsal view; F, H: habitus, lateral view. Scale bar: 0.5 mm. Habitus images not to scale.