Pleisticanthoides simplex ( Rathbun, 1932 ) Rathbun, 1932

Ng, Peter K. L. & Forges, Bertrand Richer De, 2012, Pleisticanthoides Yokoya, 1933, a valid genus of deep-sea inachid spider crabs (Crustacea: Decapoda: Brachyura: Majoidea), with descriptions of two new species from the Philippines, Papua New Guinea and Vanuatu, Zootaxa 3551, pp. 65-81 : 68-71

Pleisticanthoides simplex ( Rathbun, 1932) comb. nov.

( Figs. 2–4 )

Pleistacantha simplex Rathbun, 1932: 30 –31.— Sakai 1935: 68 –69, fig. 4, Pl. 8, fig. 2.— Sakai 1936: 78, fig. 31.— Sakai 1938: 236.— Sakai 1965: 71, pl. 31, fig. 1.— Sakai 1976: 174 –175, pl. 54, fig. 1.— Takeda & Miyake 1969: 494, fig. 9a, b.— Serène & Lohavanijaya 1973: 42 (key).—Guinot & Richer de Forges 1982: 1101.—Guinot & Richer de Forges 1985: 125, pl. 7 K.— Griffin & Tranter 1986: 52.— Ahyong et al. 2005: 1.—Ng et al. 2008: 112, 114.

Pleistacantha symplex [sic]— Sakai 1935: 68 –69, fig. 4, Pl. 8, fig. 2.

Pleisticanthoides nipponensis Yokoya, 1933: 139 , fig. 49.

Pleistacanthoides [sic] nipponensis — Sakai 1935: 68.— Sakai 1938: 237.

Pleistacantha nipponensis ? Sakai 1938: 233.— Serène & Lohavanijaya 1973: 42.

Material examined. 1 female (10.0 × 7.5 mm) ( KMNH) [lectotype female of Pleisticanthoides nipponensis Yokoya, 1933 ], station 109, southeast of Inubo-zaki, 123 m, Japan, coll. Soyo-Maru, 2 March 1927.— 1 male (12.2 × 9.6 mm), 2 females (NSMT-Cr 13193), 200 m, Japan, coll. R/V Kotaka-Maru, 25 January 1998.—1 ovigerous female (NSMT-Cr 12315), Tosa Bay, 151–155 m, Japan, coll. R/V Kataka Maru , 14 May 1997.— 1 male (NSMT- Cr 6779), station 65(D4), 178 m, Japan, coll. 6 March 1969.— 1 male (NSMT-Cr 16491), station TY- 04-X, off Amami-Oshima Island, Kagoshima, 28°22.37’N 129°15.97’E – 28°22.28’N 129°15.43’E, 290 m, Japan, coll. Toyoshio-Maru, beam trawl, 21 May 2004.

Remarks. Pleistacantha simplex was briefly described by Rathbun (1932: 30) without any figures. The carapace was described as "covered by sharp granules" and, as shown in the drawing of Sakai (1976: pl. 54), who examined the type, has some spinules on the anterior part. The ambulatory legs are long, slender and without spines. The ocular peduncle is long, thin and the cornea is not inflated. Takeda & Miyake (1969: 495: fig. 9a, b), reporting the species from the East China Sea, also provided a figure of the G1 and commented "This species has hitherto been recorded only from the Sagami Bay and the south of Goto Is at the depths of 60 to 360 m." Sakai (1976: 174) queried Takeda & Miyake’s (1969) record, commenting that the “general aspect of the two authors species rather resembles that of P. terribilis , but in that species, the anterior pleopod of male has a tiny process near the apex, which is not found in TAKEDA and MIYAKE'S figure.” Takeda & Miyake’s (1969: fig. 9a, b) figure of the G1 also agrees with the present definition of Pleisticanthoides, with the distal third appearing dorsoventrally flattened. Although the dorsal surface of the carapace is spinular and not unarmed, the shapes of the eyes, as well as the structures of the ambulatory legs and G1 fit with the present definition of Pleisticanthoides, and as such, P. s i m p l e x is here transferred to Pleisticanthoides. The present series of specimens of P. s i m p l e x agree very well with Sakai’s (1965, 1976) definition and figures of the species, with the G1 structure matching that figured by Takeda & Miyake (1969).

Yokoya (1933: 139, fig. 49) gave a short description of a male and three females of P. nipponensis . He also provided a drawing of a small but adult female specimen (9.0 × 7.0 mm) of his new species, which he made the type of his new genus Pleisticanthoides. To our knowledge, nobody has examined any specimens of this species since the description by Yokoya (1933: 139, fig. 49). Sakai (1986: 174) commented that for the type of Pleistacantha japonica , "YOKOYA's type specimen is not extant now" (see, however, Takeda & Miyake 1969). Sakai (1935: 68) under “ Pleistacantha symplex ” (sic) wrote: " Pleistacanthoides nipponensis Yokoya (1933) comes very near to this species, but I have not yet had occasion to compare the specimens." As previously discussed, Sakai (1976) eventually formally synonymized the two species when he stated that " Pleisticanthoides nipponensis YOKOYA is undoubtedly synonymous with the present species (P. s i m p l e x)". The discovery of a syntype specimen of P. nipponensis allows us to confirm Sakai’s (1976) hypothesis that it is synonymous with P. s i m p l e x. While Yokoya’s (1933) description of P. nipponensis is generally accurate, the carapace is not smooth but actually also covered with small spinules like those of P. s i m p l e x. Although this syntype female specimen has no pereiopods, the carapace features leaves no doubt that the two species are conspecific. The specimen is here designated as the lectotype of Pleisticanthoides nipponensis Yokoya, 1933 .

As far as is known, Pleisticanthoides simplex is endemic to Japan, occurring in relatively shallower waters 50–200 m deep ( Sakai 1976: 174).

Figures

FIGURE 2. Pleisticanthoides simplex (Rathbun, 1932). A, Pleisticanthoides nipponensis Yokoya, 1933 (type female) (after Yokoya 1933: fig. 49); B – D, lectotype female of Pleisticanthoides nipponensis Yokoya, 1933 (10.0 × 7.5 mm) (KMNH). A, overall dorsal view; B, dorsal view of carapace; C, ventral view of third maxillipeds and abdomen; D, lateral view of carapace.

FIGURE 3. Pleisticanthoides simplex (Rathbun, 1932), male (12.2 × 9.6 mm) (NSMT-Cr 13193), Japan. A, overall dorsal view; B, dorsal carapace view; C, third maxillipeds, antennae, antennules and orbits; D, ventral view of thoracic sternum and abdomen.

FIGURE 4. Pleisticanthoides simplex (Rathbun, 1932), male (12.2 × 9.6 mm) (NSMT-Cr 13193), Japan. A, B, left G 1. Scales = 0.5 mm.