Two new species of the Pterostichus macrogenys species group (Coleoptera, Carabidae) discovered in shallow subterranean habitats in northern Honshu, Japan

Hirotarô Itô,Kôji Sasakawa

doi:10.3897/subtbiol.21.11155

Abstract

Shallow subterranean environments have recently received attention as a habitat for Carabidae beetles, and many new species have been discovered using collection techniques devised for this habitat. We report the discovery of two new species of the macrogenys species group of the Pterostichus subgenus Nialoe Tanaka, 1958, collected by subterranean baited traps in northern Honshu, Japan. Pterostichus shinbodakensis Sasakawa & Itô, sp. n. is described from Mt. Shinbodake, Niigata Prefecture, and P. tateishiyamanus Sasakawa & Itô, sp. n. is described from the southeastern foot of Mt. Tateishiyama, Fukushima Prefecture. Comparative male genital morphology shows that among the known species, the two new species are most closely related to P. falcispinus Sasakawa, 2005 and P. chokaisanus Sasakawa, 2009, respectively. In addition, sympatric occurrence of P. shinbodakensis with a smaller, unidentified species of the species group was also confirmed. The implications of these results for future studies of the macrogenys species group, as well as those of Nialoe, are discussed.

Highlights

The taxonomy of the beetle family Carabidae has been investigated extensively in Japan, with many new species currently being described
We describe two new species of the macrogenys species group of Pterostichus subgenus Nialoe Tanaka, 1958, which we collected from Niigata and Fukushima prefectures, northern Honshu, using subterranean baited traps
A female of the macrogenys species was obtained at the type locality (8–30.viii.2015, Hirotarô Itô leg.; Fig. 9), it differs from P. 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, smaller eyes, and blackish elytra

Summary

Introduction

The taxonomy of the beetle family Carabidae has been investigated extensively in Japan, with many new species currently being described. Ito (2010) and Ito and Ogai (2015) described 17 new and one new subterranean species, respectively They collected specimens of these new species using a new type of baited trap modified for subterranean environments, which to date have received little attention as a habitat for Pterostichus in Japan (Ito 2010; Ito and Ogai 2015; see Yoshida 2012; Ito 2015). Their discovery of undescribed species indicates a need for future surveys of the habitat in other areas (Yoshida 2012). Examinations of specimens from additional localities have been expected

Materials and methods

Discussion