New species and new records of cave-dwelling money spiders from Japan with remarks on the genera Anguliphantes, Arcuphantes, Nihonella, Micrargus, and Porrhomma (Araneae, Linyphiidae)

In Japan, linyphiid spiders are relatively common inhabitants of caves and other hypogean habitats. However, their taxonomy, distribution, and sometimes even their occurrence in subterranean environments, remain poorly studied for most species. To help partially fill this knowledge gap, herein we present new taxonomic and faunistic data on Japanese cave-dwelling linyphiid species.

Particularly, we report the genus Anguliphantes Saaristo & Tanasevitch, 1996 for the first time in Japan. We provide new subterranean records, redescriptions, and detailed images of diagnostic characters for poorly known species belonging to the genera Arcuphantes Chamberlin & Ivie, 1943; Nihonella Ballarin & Yamasaki, 2021; Micrargus Dahl, 1886; and Porrhomma Simon, 1884, including the first description of the previously unknown males of Arcuphantes ashifuensis and A. longissimus.

Additionally, we describe three newly discovered cave-dwelling species: Arcuphantes iseensis sp. nov. (male, female), Nihonella tanikawai sp. nov. (male, female), and Porrhomma niimiensis sp. nov.

(female). To further support the validity of the newly described species and facilitate future identifications and research on the Japanese cave-dwelling spider fauna, we provide DNA barcodes for the species discussed and perform molecular phylogenetic and/or pairwise distance analyses for the genera Arcuphantes, Nihonella, Micrargus, and Porrhomma.