Ryuthela tanikawai, ONO, 1997

RYUTHELA TANIKAWAI ONO, 1997 View in CoL

Ryuthela tanikawai Ono, 1997, p. 157 View in CoL , figs 19–20 (description of female); Ono, 2009, p. 80, figs 38–40; Dunlop, Steffensen & Ono, 2014, p. 39 (removed from synonymy of R. ishigakiensis View in CoL , contra Tanikawa, 2013a, p. 38).

Holotype: Female deposited at NSMT (NSMT-Ar 3484), from Urauchi, Iriomotejima island, Okinawa Prefecture, Japan, 30 March 1983, by A. Tanikawa; examined.

Other material examined: Two females (XUX-2013- 200/206), collected at Mihara , Iriomotejima island, Okinawa Prefecture, Japan, 24.35°N, 123.92°E, 30 m a.s.l., 8 July 2013, collected by D. Li and B. Wu. GoogleMaps

Diagnosis: Females R. tanikawai differ from all other Ryuthela species except R. ishigakiensis s.s. by short cylinder-shaped and granulated receptacular clusters, but cannot be morphologically diagnosed from R. ishigakiensis s.s. ( Fig. 19A–D). However, R. tanikawai can be distinguished from all other Ryuthela species on Ishigakijima island by the following unique nucleotide substitutions in the standard DNA barcode alignment: T (43), G (70), C (121), G (169), T (250), T (257), T (266), C (268), C (292), A (334), A (356), T (358), A (383), T (415), G (470), G (484), T (556).

Description: Female. Carapace and opisthosoma dark brown; tergites darker brown; sternum narrow, nearly twice as long as wide; a few long pointed hairs running over ocular mound in a longitudinal row; chelicerae robust with promargin of cheliceral groove containing 13–15 vestigial denticles of variable size; legs with strong hairs and spines; opisthosoma with 12 tergites; 8 spinnerets. Measurements: BL 11.20– 11.50, CL 5.60–6.44, CW 4.38–4.70, OL 6.03–6.52, OW 4.31–4.40; ALE> PLE> PME> AME; palp 10.47 (3.52 + 1.88 + 2.19 + 2.88), leg I 12.57 (3.90 + 2.20 + 2.30 + 2.68 + 1.49), leg II 12.47 (3.72 + 2.16 + 2.18 + 2.85 + 1.56), leg III 13.26 (3.78 + 2.18 + 2.22 + 3.18 + 1.90), leg IV 18.03 (5.43 + 1.80 + 3.30 + 5.00 + 2.50).

Female genitalia. A pair of receptacular clusters along the anterior margin of bursa copulatrix, basally separated from each other, cylinder-shaped and granulated ( Fig. 19B, D), or granulated receptacular clusters close to each other at the basal part ( Fig. 19A, C).

Male. Unknown.

D i s t r i b u t i o n: I r i o m o t e j i m a i s l a n d, O k i n a w a Prefecture, Japan.

Remarks: Ono (2009) indicated some differences in male palpal organ between R. ishigakiensis s.l. and R. tanikawai based on specimens and photographs made by Haupt (2003). Contrary to this, Tanikawa (2013a) considered R. tanikawai as the synonym of R. ishigakiensis based on the lack of distinct male and female morphology to distinguish between them. In this study, we collected only two females and no males. Considering highly variable female genitalia in Ryuthela , we base our revalidation of R. tanikawai on other data sources.