Straneostichus politus, Chen & Shi & Liang, 2022

Chen, Jia-Heng, Shi, Hong-Liang & Liang, Hong-Bin, 2022, Taxonomic notes on the Chinese endemic genus Straneostichus Sciaky, 1994 (Coleoptera: Carabidae: Pterostichini), with descriptions of three new species, Zootaxa 5182 (3), pp. 247-264 : 251-253

Straneostichus politus sp. nov.

Chinese vernacular name: 光Ŕḃ步ffl

( Figures 5–7 , 21B )

Type material. Holotype: male ( IZAS), “ Sichuan Province, Wolong Town, Wuyipeng, Yuancaodi , 2450 m, primary birch forest, pitfall, 2004.VI.16–VII.1, Yu Xiaodong leg., RB3-1”/ “ HOLOTYPE Straneostichus politus sp. nov., det. Chen & Shi. 2022” [red label] . Paratypes: 1 female ( IZAS), “ Sichuan, Wolong, Wulidun , 2615 m, grassland, pitfall, 2004. VI.6–9, Yu XD leg., EG2-6” ; 1 male ( IZAS), “ Sichuan, Wolong, Wuyipeng , 2545 m, birch grove, pitfall, 2004. V.29– VI.1, Yu XD leg., HWB4-2” ; 1 male ( IZAS), “ Sichuan, Wolong, Wuyipeng , 2535 m, conifer-broadleaf forest, pitfall, 2004. VI.29–VII.14, Yu XD leg., HWM3-3” ; 1 female ( IZAS), “ Sichuan, Wolong, Wuyipeng, Yuancaodi , 2550 m, artificial larch forest, pitfall, 2004. V.1–4, Yu XD leg., RL3-1” ; 1 female ( IZAS), “ Sichuan, Wolong, Wuyipeng, 2675 m, Azalea forest , pitfall, 2004.VII.14–29, Yu XD leg., HWD1-5” ; 1 male ( CLHY), “ Sichuan Province, Ya'an City, Mt. Jiajinshan , 2019, Local leg.”

Diagnostic characters. Anterior margin of pronotum much wider than posterior margin ( PPW / APW 0.81–0.83); basal fovea with sparse punctures, mid-basal area between basal foveae impunctate; lateral margins gently sinuate before posterior angles, which are obtuse, without prominent denticle. Elytral striae without evident punctures. Median lobe of aedeagus slender; in dorsal view, left margin slightly sinuate before the apical lamella; the apical lamella distinctly longer than maximum width, slightly bent rightward; endophallic piece present on ventral surface of apical orifice, narrow and moderately sclerotized.

Comparison. This new species is most similar to S. ovipennis . Both species are recognizable among the fischeri - group by: (1) pronotum slightly narrower, PW / PL 1.12–1.19 (versus 1.20–1.34 in other species); (2) pronotal basal fovea sparsely punctate, mid-basal area between two basal foveae impunctate (versus more or less punctate on mid-basal area); (3) elytral shoulders narrower, SW/EW 0.50–0.54 (versus 0.53–0.62 in other species); (4) when in dorsal view, the apical lamella of aedeagus distinctly longer than maximum width (versus length subequal to or less than maximum width). Compared to S. ovipennis , the new species is different in: (1) pronotal anterior margin much wider than posterior margin, PPW / APW 0.81–0.83 (versus 0.95–0.96 in S. ovipennis ); (2) elytral striae impunctate (versus distinctly punctate on basal half in S. ovipennis ); (3) in dorsal view, the apical lamella of aedeagus weakly bent rightward (versus strongly bent rightward in S. ovipennis ), left margin of median lobe slightly sinuate before the apical lamella (versus evenly curved in S. ovipennis ).

Description. A medium-sized Straneostichus species (BL 11.2–12.0 mm) ( Fig. 5 ); dorsal surface reddish copper or metallic green with coppery reflections. Head impunctate; vertex distinctly punctate; lateral grooves deep, smooth and nearly straight, extending toward posterior margin of eyes. Pronotum sub-cordiform (PW/PL 1.12–1.19), lateral margins evenly curved from anterior angles to middle, sinuate before posterior angles; anterior margin nearly straight, strongly wider than basal margin (PPW/APW 0.81–0.83), posterior margin almost straight; anterior angles obtuse and rounded, not projecting; posterior angles obtuse; disc smooth; basal foveae deep and weakly punctate, area between basal foveae impunctate. Elytra oviform (EL/EW 1.43–1.46), maximum width behind middle (AEL/ EL 0.51–0.53); shoulders strongly narrowed and rounded, humeral teeth small but distinct; basal ridge complete, forming a distinct obtuse angle with lateral margin of elytra; intervals weakly convex, striae impunctate, relatively deep; microsculpture isodiametric; umbilicate series on interval IX composed of approximately 15–19 pores, sparse in middle and dense in anterior and posterior areas. Male genitalia ( Figs. 6–7 ). Median lobe of aedeagus moderately thick; in lateral view, basal portion strongly expanded, apex gradually narrowed and bent downwards, the apical lamella a little thickened; in dorsal view, the apical lamella distinctly longer than maximum width, gradually bent rightward, left margin weakly sinuate, apex rounded; endophallic piece present on ventral surface of apical orifice, narrow and moderately sclerotized.

Etymology. The scientific name of the new species is derived from the Latin root "polit-" meaning polished and smooth, referring to its impunctate elytral striae.

Distribution. Only known from two adjacent localities in the central part of Sichuan Province.

Figures

FIGURE 21. Pronotum hind angle and basal area of Straneostichus species (fischeri-group). A. S. ovipennis (Songpan, Sichuan); B. S. politus sp. nov. (Baoxing, Sichuan); C. S. haeckeli (Meixian, Shaanxi); D. S. fischeri (Zêkog, Qinghai); E. S. puetzi (Songxian, Henan); F. S. liupanensis sp. nov. (Jingyuan, Ningxia); G. S. ganqingensis sp. nov. (Xunhua, Qinghai). Scales: 1.0 mm.

FIGURES 5‒7. Straneostichus politus sp. nov. 5. dorsal habitus, a male paratype (Baoxing, Sichuan); 6‒7. median lobe of aedeagus: dorsal (A), ventral (B) and right lateral view (C); 6. Paratype (Baoxing, Sichuan); 7. holotype. Scale: 5.0 mm for 5; 0.5 mm for other.