Nihonella gen. nov., a new troglophilic genus of dwarf spiders from Japan with a discussion on its phylogenetic position within the subfamily Erigoninae (Araneae, Linyphiidae)

Francesco Ballarin,Takeshi Yamasaki

doi:10.5852/ejt.2021.733.1215

Abstract

A new monospecific genus belonging to the family Linyphiidae Blackwell, 1859, Nihonella gen. nov., is described using an integrative taxonomic approach based on the species N. chika gen. et sp. nov. The new genus is endemic to Western Honshu, Japan, and it shows distinctive genitalic and somatic characters of other genera of the subfamily Erigoninae Emerton, 1882. Nihonella gen. nov. is found only in the twilight and transition zones of caves in Okayama and Nara Prefectures. The phylogenetic position of Nihonella gen. nov. within the subfamily Erigoninae, and its relationship as a sister clade of the species of the group of Savignia Blackwell, 1833 (sensu Millidge 1977), is discussed on the basis of both, morphological and molecular evidence.

Highlights

Within the order Araneae, the spider family Linyphiidae Blackwall, 1859 is the second largest by number of species: currently 4638 species are known in 617 genera, with a worldwide distribution (World Spider Catalog 2020)
While collecting in caves in Central and Western Honshu, Japan, we found several specimens of spiders belonging to different families, including some Linyphiidae
The peculiar somatic characters, as well as the shape of the epigyne and male palp, excluded this species from the currently known genera. We describe this spider as a new species, and we establish a new genus on the basis of morphological and molecular evidence

Summary

Introduction

Within the order Araneae, the spider family Linyphiidae Blackwall, 1859 is the second largest by number of species: currently 4638 species are known in 617 genera, with a worldwide distribution (World Spider Catalog 2020). In Japan, 293 linyphiid species belonging to 109 genera are currently recorded (Tanikawa 2020). While collecting in caves in Central and Western Honshu, Japan, we found several specimens of spiders belonging to different families, including some Linyphiidae. A detailed morphological analysis of the collected material led to the discovery of an unknown linyphiid species belonging to the subfamily Erigoninae. We describe this spider as a new species, and we establish a new genus on the basis of morphological and molecular evidence. To support this claim and to clarify the phylogenetic position of the new genus within the subfamily Erigoninae, we conducted a multi-locus phylogenetic analysis, the results of which are discussed

Methods

Results

Conclusion