Ryuthela hirakubo, Xu & Liu & Ono & Chen & Kuntner & Li, 2017

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 : 901-904

RYUTHELA HIRAKUBO SP. NOV.

urn:lsid:zoobank.org:act:88535314-B431-4EF0-AEA2-9871DFB2EFDB

Holotype: Male (XUX-2013-231, matured 12 November 2013, at CBEE, College of Life Sciences, Hubei University) collected at Hirakubo River, Ishigakijima island, Okinawa Prefecture, Japan, 24.59°N, 124.32°E, 125 m a.s.l.; 10 July 2013, by D. Li and B. Wu.

Paratypes: Ten females and four juveniles [XUX-2013- (222–228, 230/232–239)] and one male (XUX-2013-228 matured 5 November 2013, matured 10 October 2013, at CBEE, College of Life Sciences, Hubei University ) collected at the same locality as holotype, 10 July 2013, by D. Li and B. Wu .

Etymology: The species epithet, a noun in apposition, refers to the type locality.

Diagnosis: Male of R. hirakubo sp. nov. is similar to R. ishigakiensis s.s. and R. banna sp. nov., but it can be distinguished from them by the straight contrategular spine and the terminal shape of the contrategulum in retrolateral review ( Fig. 17A, C, E); it differs from other Ryuthela species by the contrategulum with two edges, and the longer contrategulum, and the wide separation of tegulum from contrategulum ( Fig. 17C, E). Females R. hirakubo sp. nov. can be distinguished from other species of Ryuthela on the Ishigakijima island and Iriomotejima island by the paired receptacular clusters basally close to each other and bifurcated ( Fig. 17F, G). Ryuthela hirakubo sp. nov. can also 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 (19), T (31), G (49), G (142), C (169), A (184), T (196), C (202), C (223), A (244), T (370), C (403), G (487), C (499), C (505), T (547), C (595), T (604), T (616).

Description: Male (holotype). 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 10–11 vestigial denticles of variable size; legs with strong hairs and spines; opisthosoma with 12 tergites; 7 spinnerets. Measurements: BL 8.20–10.20, CL 4.80–5.45, CW 4.00–4.50, OL 4.40–5.00, OW 3.10– 3.30; ALE> PLE> PME> AME; leg I 14.65 (3.65 + 2.00 + 2.90 + 3.90 + 2.20), leg II 14.80 (3.70 + 1.90 + 2.80 + 4.00 + 2.40), leg III 15.40 (3.90 + 1.60 + 2.60 + 4.50 + 2.80), leg IV 20.00 (4.95 + 2.00 + 3.55 + 5.50 + 4.00).

Palp. Prolateral paracymbium unpigmented and unsclerotized, numerous setae and spines at the tip of paracymbium ( Fig. 17A); contrategulum with a long and straight spine and with two edges not fused at the distal parts in retrolateral view ( Fig. 17A, C, D, E); the distal part of terminal apophysis of tegulum thumb-shaped in retrolateral view ( Fig. 17C, E); embolus with a wide basal part ( Fig. 17E). In retrolateral view, the basal tegulum locates approximately at the middle basal part of embolus ( Fig. 17C, E).

Female. Coloration darker than that of males; chelicerae robust with promargin of cheliceral groove containing 12–16 strong denticles of variable size; legs and opisthosoma as in the male; 7–8 spinnerets. Measurements: BL 10.00–12.80, CL 5.20–6.50, CW 4.21–5.32, OL 5.00–6.40, OW 3.28–5.25; ALE> PLE> PME> AME; palp 10.76 (3.81 + 1.95 + 2.20 + 2.80), leg I 12.61 (4.11 + 2.18 + 2.30 + 2.50 + 1.52), leg II 13.03 (4.00 + 2.30 + 2.30 + 2.91 + 1.52), leg III 13.64 (3.72 + 2.30 + 2.28 + 3.45 + 1.89), leg IV 20.23 (5.60 + 2.68 + 3.62 + 5.55 + 2.78).

Female genitalia. A pair of receptacular clusters along the anterior margin of bursa copulatrix, basally close to each other and bifurcated ( Fig. 17F, G).

Distribution: Ishigakijima island (Hirakubo), Okinawa Prefecture, Japan.