Pterostichus (Nialoe) tateishiyamanus Sasakawa & Ito

Sasakawa, Koji & Ito, Hirotaro, 2017, Two new species of the Pterostichusmacrogenys species group (Coleoptera, Carabidae) discovered in shallow subterranean habitats in northern Honshu, Japan, Subterranean Biology 21, pp. 47-56 : 50-53

Pterostichus (Nialoe) tateishiyamanus Sasakawa & Ito sp. n. Figs 10, 11, 21, 22

Type materials.

Holotype: ♂, Kuratani-sawa, alt. 480 m, Ôaza-Iine, Okugawa, Nishiaizu-machi, Yama-gun, Fukushima Prefecture, Japan (37.752944 N, 139.683889 E), 18. v– 9.vi.2014, Hirotarô Itô leg. Paratypes: 1♂, same data as holotype; 1♀, same locality, but alt. 500 m, 1-14.xi.2015, Hirotarô Itô leg.

Etymology.

Derived from Mt. Tateishiyama, on the southeastern foot where the type locality is situated.

Diagnosis.

Externally similar to other small-sized species of the macrogenys species group but readily distinguished by the bifurcated distal end of the left preapical lobe.

Measurements.

[holotype ♂/paratype ♂/paratype ♀] BLm: 14.7/13.6/14.6 mm; BLl: 13.5/12.6/13.4 mm; BLc: 12.9/12.2/12.8 mm; HL/HW: 0.95/0.83/0.86; PL/PW: 0.71/0.70/0.71; PAW/PW: 0.87/0.86/0.86; PPW/PW: 0.77/0.71/0.72; EL/EW: 1.71/1.78/1.68.

Description.

Head, pronotum, and elytra dark brown to blackish; appendages dark brown. Dorsal surface almost smooth except for laterobasal impressions of the pronotum, which are slightly punctate.

Head large, widest at tempora, which are distinctly swollen; width at the widest point larger than pronotal posterior margin width; length from clypeal apex to neck base larger than pronotum length along the median line. Left mandible large and curved at the apical 1/4; length between mandible apex and posterolateral end on dorsal side ~2.2-fold as long as the anterior width of the clypeus. Eyes weakly convex, with the anterior-posterior length longer than 1/2 length of antennal segment 1. Antennal segment 2 with two setae.

Pronotum cordate, notably flat, widest at apical 1/5. Lateral margins arcuate on apical 2/3, slightly sinuate on basal 1/3; two marginal setae on each lateral side, anterior setae near widest pronotal point and posterior setae near hind angles. Anterior margin emarginated, with curvature approximately the same as that of apical 2/3 of lateral margins; anterior angles notably pronounced in the female, less pronounced in the male. Posterior margin emarginated at median area, almost straight at lateral areas; hind angles right-angled. Median line impressed in the middle, reaching the posterior margin in the holotype male but not reaching both anterior and posterior margins in the paratype male and female; laterobasal impressions single, shallow.

Elytra almost parallel-sided, less convex; shoulder distinct, but not denticulate; apices rounded; scutellar stria present, connected to stria 1 in the male specimens; in the paratype female, stria 1 disconnected at the level of the posterior end of the scutellar stria, where only the scutellar stria is connected to the other part of stria 1; one setigerous puncture on stria 1 at the level of the posterior end of the scutellum; two setigerous punctures on interval 3, anterior one slightly behind the middle and posterior one on apical 1/5-1/4, both adjoining stria 2. Hind wings completely atrophied. Male sternum 7 slightly concave. Female first fore tarsomere without adhesive hairs on ventral side.

Aedeagus stout without tubercle. Endophallus short, stout, strongly bent ventrally, with gonopore directed backward; left pigmented band weakly sclerotized; right preapical lobe small; left preapical lobe large, with bifurcated distal end; left apical lobe bifurcated, with slender and narrowly rounded apices. Left paramere square. Right paramere short, straight, rounded apically.

Remarks.

Among the known members of the macrogenys species group, this species is considered the most closely related to Pterostichus chokaisanus , because the two species have slender and narrowly rounded bifurcated apices of the left apical lobe; this character is found only in these species among the species group and thus is an apomorphic character state.