山﨑 健史

Two new species of Galloisiana Caudell, 1924, G. harimensis sp. nov . and G. kawamurai sp. nov ., are described. In general appearance, both new species resemble G. nipponensis (Caudell & King, 1924), the type species of the genus. Molecular phylogeny reconstructed in the present study shows that the new species belong to clades different from that of G. nipponensis . Morphologically, the three species can be distinguished based on the male genitalia, although the females resemble each other.

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.

Genetic disturbance can be caused by the release or escape of individuals with different genetic characteristics into wild habitats, risking impacts on native biodiversity. The risk of genetic disturbance in pet insects due to release and escape is particularly common because a wide variety of affordable pets are available on the market. Trypoxylus dichotomus (Coleoptera, Scarabaeidae), the Japanese rhinoceros beetle, is a renowned pet insect in Japan and thus is a suitable target species for studying genetic disturbances in pet insects. However, the detailed spatial genetic structure and genetic disturbances of this species in Japan remain unclear. Here, we estimated the genetic diversity and spatial genetic structure of wild and marketed individuals using mitochondrial DNA sequences and genome-wide single-nucleotide polymorphisms (SNPs) obtained via MIG-seq. Using MIG-seq, 570 SNPs were obtained, revealing a weak yet significant spatial genetic structure in the Japanese archipelago. Although significant isolation by distance (IBD) was observed in wild individuals, no significant IBD was observed in marketed individuals. Comparisons between wild and marketed individuals revealed clear differences in spatial genetic structure. These findings highlight the risks of releasing marketed individuals into the wild owing to their artificial long-distance migration. Our results provide valuable insights into the genetic disturbance of human-mediated distribution and underscore the need for informed management practices to protect native biodiversity.