The Pterostichus macrogenys species group is an endemic subterranean Japanese carabid lineage that shows marked regional differentiation, but unresolved taxonomic issues remain, even at the species level. Based on morphological examinations of the genital structures of newly collected specimens and an external morphometric analysis of all the species concerned, P. falcispinus Sasakawa, 2005 syn. nov. is synonymized with P. asahinus Habu & Baba, 1960, and P. awashimaensissp. nov. is described

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... m Awashima Island, a small island off the coast of Honshu. Based on external morphometrics, P. awashimaensis was determined to be most similar to P. yahikosanus Sasakawa, 2009, but its external and genital features differ distinctly from the latter species and it is thought to be more ancestral.