Pterostichus (Nialoe) shinbodakensis 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 : 49-50

Pterostichus (Nialoe) shinbodakensis Sasakawa & Ito sp. n. Figs 8, 12-18

Type material.

Holotype, ♂, Mt. Shinbodake, alt. 540 m, Murakami-shi, Niigata Prefecture, Japan (38.355444 N, 139.516222 E), 6-27.ix.2015, Hirotarô Itô leg.

Etymology.

Derived from the name of the type locality.

Diagnosis.

Similar to Pterostichus takadateyamanus and Pterostichus falcispinus but distinguished by the shape of right paramere (Figs 16-20; Sasakawa 2009b, Fig. 20) and distinctly sclerotized left pigmented band (in Pterostichus takadateyamanus and Pterostichus falcispinus , only slightly sclerotized). Readily distinguished from sympatrically occurring unidentified species (Fig. 9) by a larger body size and smaller eyes (see Remarks).

Measurements.

BLm: 16.7 mm; BLl: 14.9 mm; BLc: 14.3 mm; HL/HW: 0.89; PL/PW: 0.64; PAW/PW: 0.89; PPW/PW: 0.77; EL/EW: 1.55.

Description.

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

Head large, widest at tempora, which are markedly swollen; width at the widest point larger than pronotal posterior margin width; length from clypeal apex to neck base longer than pronotum length along the median line. Left mandible large and strongly hooked at the apical 1/3; length between mandible apex and posterolateral end on dorsal side over 2.5-fold longer than the anterior width of the clypeus. Eyes small and barely convex, with anterior-posterior length shorter than 1/2 length of the 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 contour arched more strongly than the curvature of apical 2/3 of lateral margins; anterior angles notably produced. Posterior margin emarginated at median area, almost straight at lateral areas; hind angles right-angled. Median line impressed in the middle, not reaching both the anterior and posterior margins; laterobasal impressions single, shallow.

Elytra almost parallel-sided, less convex; shoulder distinct, but not denticulate; apices rounded; scutellar stria present, not connected to stria 1; 1 setigerous puncture on stria 1 at the level of the posterior end of scutellum; two setigerous punctures on interval 3, anterior one slightly behind the middle and posterior one on apical 1/6, both adjoining stria 2. Hind wings completely atrophied. Male sternum 7 fairly concave.

Aedeagus stout, without tubercle. Endophallus short, stout, strongly bent ventrally, with gonopore directed backward; left pigmented band distinctly sclerotized; right preapical lobe stout, as long as left preapical lobe, with apical part bent toward gonopore; left preapical lobe short, stout, directed toward leftward, with apex narrowly rounded; left apical lobe small but stout, strongly bent backward, with surface distinctly sclerotized. Left paramere square. Right paramere bent at approximately 120° at apical 2/5; apical part from dorsal view almost flat, with large, widely rounded right corner; ventral side strongly concave.

Remarks.

This species is considered most closely related to Pterostichus falcispinus , because the angle bending (Fig. 17) and the wide apical part (Fig. 16) of the right paramere and the strongly-bent, distinctly sclerotized left preapical lobe (Figs 12-14) are found in only these species among the known Nialoe species (i.e., putative synapomorphies). In other consubgeneric species, the right paramere is short, straight with a rounded apical part or slender, arcuate with a narrow apical part (i.e., not bent at an angle and not with a flat apical part), and the left preapical lobe is not distinctly sclerotized.

Although a female of the macrogenys species was also obtained at the type locality (8-30.viii.2015, Hirotarô Itô leg.; Fig. 9), it differs from Pterostichus shinbodakensis in several ways: a smaller body size (BLm: 14.0 mm; BLl: 12.7 mm; BLc: 12.2 mm), a left mandible that is not elongated (length between mandible apex and posterolateral end on dorsal side is ~2.2-fold as long as the anterior width of the clypeus), smaller eyes (anterior-posterior length is longer than one-half the length of the antennal segment 1), and blackish elytra. Considering the characters of the other species in the group (Figs 10, 11; Sasakawa 2005, 2009b) and direct ( Ito and Ogai 2015) and indirect ( Sasakawa 2009b) evidence for sympatric occurrence of large and small species in some localities, the focal morphological differences would be between large ( Pterostichus shinbodakensis ) and small species (the focal female), rather than between sexes within the same species. To determine its taxonomic status, male specimens need to be investigated.