Review of the spider genus Solenysa Simon, 1894 in Western Japan and Central Ryukyu with the description of three new species (Araneae, Linyphiidae)

Three new species of the genus <i>Solenysa</i> Simon, 1894 are recorded and described from Western Japan, all based on both sexes. Of these, two species are endemic to the Ryukyu Archipelago: <i>S.shimatchu</i> Ballarin & Eguchi, <b>sp. nov.</b> from Amami-Ōshima Island, and <i>S.yambaruensis</i> Ballarin & Eguchi, <b>sp. nov.</b> from Okinawa Honto and Kume-jima Islands. These species represent the first record of the genus <i>Solenysa</i> for the Central Ryukyus and belong to a newly defined species group. Another new species, <i>S.bilamellata</i> Ballarin & Eguchi, <b>sp. nov.</b> is recorded from eastern Kyushu in mainland Japan and belongs to the <i>mellotteei</i> group. The phylogenetic positions of the new species are discussed based on morphological and molecular data. New records, remarks, and photos of genitalia of other poorly known <i>Solenysa</i> species from surrounding areas (Taiwan, Kyushu, Shikoku, and western Honshu) are provided to facilitate future identifications.