Ryuthela ishigakiensis, HAUPT, 1983

Xu, Xin, Liu, Fengxiang, Ono, Hirotsugu, Chen, Jian, Kuntner, Matjaž & Li, Daiqin, 2017, Targeted sampling in Ryukyus facilitates species delimitation of the primitively segmented spider genus Ryuthela (Araneae: Mesothelae: Liphistiidae), Zoological Journal of the Linnean Society 181, pp. 867-909 : 899

RYUTHELA ISHIGAKIENSIS HAUPT, 1983

Ryuthela nishihirai ishigakiensis Haupt, 1983, p. 287 , figs 9f, 10c–d, 12f, 13h (description of male and female); Haupt, 2003, p. 71, figs 48C–D, 52C-E, 53.25-33, 62B. Ryuthela ishigakiensis Ono, 1997, p. 150 (elevated from subspecies); Ono, 2009, p. 80, figs 33–37.

Material examined: Nine females [XUX-2013- (240–242, 244–249)] and one male (XUX-2013-243 matured 5 November 2013 at CBEE, College of Life Sciences, Hubei University), collected at Mt. Kara dake, Ishigakijima island, Okinawa Prefecture, Japan, 24.40°N, 124.24°E, 75 m a.s.l., 10 July 2013, by D. Li and B. Wu .

Diagnosis: Male of R. ishigakiensis s.s. is similar to Ryuthela banna sp. nov. and Ryuthela hirakubo sp. nov. (see below for the description), but it can be distinguished from R. banna sp. nov. by the long and curved contrategular spine and the fusion of the inner serrate margin of the upper edge and the lower edge at the distal part of contrategulum ( Fig. 15A, C, E); from R. hirakybensis sp. nov. by the curved contrategular spine and the sharp lower edge of contrategulum ( Fig. 15C, E); and from other Ryuthela species by the contrategulum with two edges ( Fig. 15C, E) and the wide separation of tegulum from contrategulum ( Fig. 15C, E). Female genitalia of R. ishigakiensis s.s. lack diagnostic characters from other species on Ishigakijima island and Iriomotejima island ( Fig. 15F–K). However, R. ishigakiensis s.s. can be diagnosed from all other Ryuthela species on Ishigakijima island and Iriomotejima island by the following unique nucleotide substitutions in the standard DNA barcode alignment: C (7), G (16), C (139), C (154), T (188), C (220), T (331), C (343), C (379), G (385), T (454).

Description: Male. Carapace and opisthosoma light 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 10 vestigial denticles of variable size; legs with strong hairs and spines; opisthosoma with 12 tergites; 8 spinnerets. Measurements: BL 11.15, CL 5.70, CW 5.30, OL 5.50, OW 4.40; ALE> PLE> PME> AME; leg I 15.10 (3.80 + 2.00 + 2.80 + 4.00 + 2.50), leg II 16.85 (4.70 + 1.35 + 3.50 + 4.40 + 2.90), leg III 15.90 (3.50 + 2.10 + 2.90 + 4.30 + 3.10), leg IV 23.15 (5.80 + 2.00 + 3.90 + 7.35 + 4.10).

Palp. Prolateral paracymbium unpigmented and unsclerotized, numerous setae and spines at the tip of paracymbium ( Fig. 15A); contrategulum with a long and curved spine, and with two edges, the upper edge with two margins (inner one with serrate margin and the outer one with smooth margin) and the lower edge ( Fig. 15C, E); the distal part of the inner serrate margin fused with the lower edge ( Fig. 15C, E); the terminal apophysis of tegulum blunt ( Fig. 15C, E); embolus with a wide basal part ( Fig. 15E). In retrolateral view, the terminal apophysis of tegulum located approximately at the middle basal part of embolus ( Fig. 15C, E).

Female. Coloration darker than that of male; chelicerae robust with promargin of cheliceral groove containing 12–16 strong denticles of variable size; legs and opisthosoma as in the male; 8 spinnerets. Measurements: BL 11.40–14.48, CL 5.88–7.80, CW 5.00–6.25, OL 6.50–7.65, OW 4.60–5.60; ALE> PLE> PME> AME; palp 10.56 (3.64 + 1.82 + 2.30 + 2.80), leg I 12.40 (3.95 + 2.10 + 2.45 + 2.60 + 1.30), leg II 12.07 (3.60 + 2.10 + 2.25 + 2.67 + 1.45), leg III 12.52 (3.65 + 1.90 + 2.40 + 3.32 + 1.25), leg IV 18.20 (5.15 + 1.90 + 3.25 + 5.10 + 2.80).

Female genitalia. A pair of receptacular clusters along the anterior margin of bursa copulatrix, basally separated from each other, cylinder shaped and granulated ( Fig. 15G–H, J–K), or basally fused ( Fig. 15F, I).

Distribution: Ishigakijima island (Mt. Kara dake), Okinawa Prefecture, Japan.

Remarks: The holotype locality of R. ishigakiensis is at Mt. Omoto dake, which is located at the central Ishigakijima island ( Haupt, 1983). Our specimens were collected at Mt. Kara dake at the eastern Ishigakijima island. We did not examine the holotype of this species, but based on male and female illustrations, we consider the specimens collected from Mt. Kara dake as R. ishigakiensis s.s.