山﨑 健史

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.

Abstract Salticidae (jumping spiders) usually exhibit pronounced sexual dimorphism in adult morphology, particularly body coloration and size and shape of the first legs. Consequently, the male and female from the same species might be erroneously assigned to different species or even different genera, which could generate synonymies in classification if only morphological data were used. Phintella is a species‐rich genus of Salticidae, which currently exhibits 76 named species. However, the male–female counterpart is unknown for nearly half of the species. In this study, we used a molecular approach to delineate the species boundaries for Phintella and Phintella‐like specimens collected in Vietnam, using morphological information as supporting data. We used three gene fragments (mitochondrial COI, 16S‐ND1, and nuclear 28S) and biogeographical considerations for species delimitation. A total of 22 putative species were recognized: 18 species of the genus Phintella, one species of the genus Lechia (L. squamata), and three species of the genus Phinteloides. Eleven undescribed species were discovered, of which seven have a male–female combination, two species have only males, and two species have only females. The crown age of Phintella was estimated at the Serravallian stage of the Miocene after the increase of species number around 16 MYA. The crown ages of most putative species recognized in this study were estimated in the Pleistocene, and the divergence among sister species likely occurred from the mid‐Miocene to the Pliocene. Our ancestral range reconstruction results showed that the diversification of our ingroup was governed by progressive dispersal events, i.e., Phintella and their related species in Vietnam diversified while expanding their range on the continent. Our results provide fundamental biodiversity data for a high‐diversity genus in Vietnamese Phintella spiders.