Stenothemus acutiapicis Y. Yang et X. Yang, 2021

Ge, Shujuan, Yang, Xingke, Liu, Haoyu & Yang, Yuxia, 2021, Definitions of two species groups of Stenothemus Bourgeois (Coleoptera, Cantharidae), with descriptions of three new species from China, Zootaxa 5047 (2), pp. 139-152 : 148-149

Stenothemus acutiapicis Y. Yang et X. Yang , sp. nov.

Figs 2C , 3G‒I

Type material. Holotype ♂ ( IZAS, IOZ (E)2003381), China, Xizang, N. Mêdog, 29.3319º N, 95.2397º E, 1005 m, 14.VIII.2015, H.B. Liang leg.

Description. Body length: 9.7 mm; width: 2.4 mm

Male ( Fig. 2C ). Coloration. Body yellow, head pitch black on dorsum, antennae black, yellow at apex of each antennomere, pronotum pitch black, dark reddish brown at anterior angles, elytra pitch black, legs black, yellow at coxae, trochanters and basal two-thirds of femora. Body densely covered with short, semi-recumbent pale-yellow pubescence, sparsely on pronotum.

Head. Surface densely punctate, each side with a smooth and rectangular impression behind antennal socket; eyes large, strongly protruding, head width across eyes nearly as long as anterior margin of pronotum; terminal maxillary palpomeres long-triangular, widest in the middle; antennae filiform, slightly extending over elytral midlength, antennomeres II 1.2 × as long as wide at apices, III 2.1 × longer than II, IV‒XI cylindrically thickened and each with a small and smooth oval impression in the middle of inner edge, IV longest, XI longer than X, pointed at apex.

Pronotum 1.25 × as wide as long, anterior margin arcuate, lateral margins sinuate and converging posteriorly, posterior margin bisinuate and narrowly bordered, anterior angles subrounded, posterior angles sharp and protruding, disc strongly convex on postero-lateral parts, surface sparsely punctate.

Elytra 2.9 × as long as humeral width, 4.9 × as long as pronotum, lateral margins moderately diverging posteriorly, surface densely punctate, longitudinal costae hardly visible.

Male genitalia ( Figs 3G‒I ). Strongly swollen laterally at basal part in ventral view; basal piece 0.9 × as long as dorsal plates, with a moderately large, bifurcate conjoined middle nodule at base of ventral side; ventral processes of parameres obliquely diverging apically in ventral view, thickened apically, bent dorsally in lateral view; dorsal plates longer than ventral processes, evenly narrowed apically, acute at outer apical angles, shallowly and roundly emarginate at inner margins in dorsal view, each present with a longitudinal ridge in lateral view, which extending from apical outer angle; laterophyses parallel to dorsal plates, conjoined and expanded apically, divided and obtusely hooked at apices, obviously exceeding over middle emarginate area between dorsal plates in dorsal view.

Female. Unknown.

Diagnosis. The new species resembles S. parameratus sp. nov. according to the body coloration and the structure of male genitalia, but can be differentiated from the latter by the male antennae which are shorter and slightly over half length of elytra, antennomeres II are shorter and 1.2 × as long as wide at apices, III are more than twice longer than II (2.1 ×); male genitalia is strongly swollen laterally at basal part in ventral view, dorsal plates are longer than ventral processes of parameres, with outer apical angles acute. In comparison, in S. parameratus , the male antennae are longer and extend to apical one-third length of elytra, antennomeres II are longer and 1.7 × as long as wide at apices, III are less than twice longer than II (1.8 ×); male genitalia is moderately swollen laterally at basal part, dorsal plates are nearly as long as ventral processes of parameres, with outer apical angels subrounded.

Etymology. The specific name is derived from the Latin acutus (acute) and apex (tip), referring to its dorsal plates of parameres of the male genitalia being acute at its outer apical angles.

Distribution. China (Xizang).

Figures

FIGURE 2. Habitus of Stenothemus, dorsal view: A. S. nigritibius sp. nov.; B. S. parameratus sp. nov.; C. S. acutiapicis sp. nov. Scale bars: 2.0 mm.

FIGURE 3. Male genitalia of Stenothemus (A, D, G. ventral view; B, E, H. dorsal view; C, F, I. lateral view): A‒C. S. nigritibius sp. nov.; D‒F. S. parameratus sp. nov.; G‒I. S. acutiapicis sp. nov. Scale bars: 1.0 mm.