Integrative taxonomy of the genus Nesticus in central Japan, with the description of a new species and redescriptions of N. echigonus and N. gondai (Araneae, Nesticidae)

Species of the genus Nesticus (Araneae, Nesticidae) in central Japan are revised based on morphological and molecular analyses of specimens collected from Niigata and Gunma Prefectures. Among them, a putative undescribed species was discovered having clearly distinguishable morphological characters from other known species in the same area. A phylogenetic analysis based on the mitochondrial COI gene was carried out using a maximum-likelihood method to confirm its distinctiveness.

The new species, Nesticus yamabushi sp. nov., is described based on specimens of both sexes. Furthermore, we provide detailed redescriptions of two other closely related species, N. echigonus and N. gondai, to address the lack of information in their original descriptions and facilitate future identifications. This study enhances our understanding of the fauna and diversity of the genus Nesticus in central Japan and provides a foundation for future taxonomic research.