Ryuthela, HAUPT, 1983

GENUS RYUTHELA HAUPT, 1983 View in CoL

Diagnosis: Ryuthela males can be distinguished from all other Heptathelinae genera by lacking the conductor and by the contrategulum with an elongated spine (i.e. Fig. 8A, C, E). The females differ from Heptathela , Qiongthela , Sinothela , Songthela and Vinathela by one pair of receptacular clusters close to each other (i.e. Fig. 5A–V), located at the anterior margin of the bursa copulatrix, and from Ganthela by receptacular clusters without stems ( Xu et al., 2015b). Ryuthela body length varies from 6.5 to 14.5 mm, and Ryuthela species can have seven or eight spinnerets.

Distribution: Ryuthela species are restricted to Ryukyu archipelago and are found from central Ryukyus (Okinawa group) to southern Ryukyus. Ryuthela species on central Ryukyus share habitats with Heptathela species ( Xu et al., 2016).

Composition: After this revision, Ryuthela contains 15 species.

Remarks: Seven of the 15 delimited species with male and female specimens can be diagnosed from each other morphologically. For the other eight species without males, especially for those that are distributed on the same islands, the species-specific nucleotide changes in the standard DNA barcode alignment were used to augment insufficient morphological diagnoses.