Ctenocheles balssi Kishinouye, 1926

(Fig. 2)

? Pentacheles nOv. Sp.?—BalSS 1914: 75, fig. 43.

Ctenocheles balssi KiShinOuye, 1926: 63 –66, fig. 1.— MakarOv 1938: 75 –77, fig. 29.—HOlthuiS 1967: 377.— Suzuki 1979: 296, pl. 18 fig. 234.— NOguchi & Akamine 1992: 25, fig. 1. — MatSuzawa & HayaShi 1997: 39 –44, figS 1–3.— Sakai 1999a: 88 –94, figS 1–3.— Sakai 2005: 240 –241.— Sakai & Sawada 2006: 1358, figS 13, 14.—Sakai 2011: 487. Tosacallianassa hatasagaensis Sakai, 2016: 814 –817, figS 1–3. Syn. nov.

Material examined. Holotype, SMF 49248, female (TL/CL 49.0/12.0 mm, lacking larger cheliped on left side), Tosa-Saga, Hata-gun, Kochi Prefecture, leg. K. Sakai, 10.iii.1988, c. 100 m deep, by fishery trawl.

Remarks. Our examination of the holotype of Tosacallianassa hatasagaensis Sakai, 2016 shows that the species belongs to the family Ctenochelidae Manning & Felder, 1991. More careful comparison of the figures with those of Ctenocheles balssi Kishinouye, 1926 leads to the conclusion that the two species are synonymous. Ctenocheles balssi was described in moderate detail with an illustration of the habitus of the 100-mm-long female holotype. The type locality is deep water at Ohsu, near Kashiwasaki, Niigata-ken, in the Sea of Japan. The species has been redescribed and reillustrated in more detail twice, both times based on the same new material from off Shikoku Island on the south side of Japan, in the northwestern Pacific Ocean. The first was by Matsuzawa & Hayashi (1997) who had 40 detached chelipeds, a male (TL 70 mm), a female (TL 61 mm) and a female abdomen from off None, Toyocho, east coast of Muroto Peninsula, at depths of 30–150 m. Sakai (1999a) also described and illustrated the same two specimens (remeasured at TL 77 and 69 mm). Tosacallianassa hatasagaensis was described from a damaged female (TL 49 mm) from Tosa-Saga, Hata-gun, Kochi Prefecture, Japan, at 100 m depth (Sakai 2016), a locality not far from Muroto Peninsula. Of these specimens, only the type of Tosacallianassa hatasagaensis lacks the unique pectinate major cheliped that above all characterises Ctenocheles. Besides this feature, the genus differs from other callianassoids in the combination of possession of a crested pointed rostrum, a pediform maxilliped 3, a uropodal exopod with a distal notch separating the anterior and posterior margins, a minor cheliped with linear ischium and merus, barrel-shaped propodal palm with thin fingers a little longer than the palm, the pereopod 3 propodus without a lower-proximal heel, and a female pleopod 2 with oval rami bearing an elongate appendix interna on the endopod. Tosacallianassa hatasagaensis shares all these features.

Ctenocheles Kishinouye, 1926 includes six described extant species, plus 22 fossil species (Hyžný & Poore 2016) differing primarily in the rostral dentition, possession or not of a maxillipedal 3 exopod, spination of the ischium and merus of the cheliped, shape of the uropodal rami, dentition of the major cheliped, and shape of the telson. Matsuzawa & Hayashi (1997) provided a key to distinguish the extant species. To these can be added C. plantei (Burukovsky, 2005) (see below). The serrated rostrum and absence of a maxilliped 3 exopod are unique to C. balssi.

The figures of Tosacallianassa hatasagaensis, confirmed by our examination of the holotype, show that the minor cheliped, pereopod 3, peduncles of the antenna and antennule, and telson are virtually identical to the figures of C. balssi (Matsuzawa & Hayashi 1997, Sakai 1999a). The earlier papers figured the merus of maxilliped 3 with a small distal tooth, not apparent on Sakai’s (2016) figure, and a cardiac prominence, said by Sakai (2016) to be lacking in his new family. Both the meral tooth (Fig. 2 A) and the cardiac prominence (Fig. 2 B) are present on the holotype of T. hatasagaensis. Sakai (2016; fig. 3A) misinterpreted pleopod 1 (Fig. 2 C) and his figure 1D shows the cornea to be asymmetrical which they are not (Fig. 2 D).

Ctenocheles balssi has been reported from the northern coast of Honshu, in the Sea of Japan (Kishinouye 1926, Noguchi & Akamine 1992, Suzuki 1979), and from the southeastern coast in Sagami Bay (Balss 1914) and off None, east coast of Muroto Peninsula, Shikoku Island (Matsuzawa & Hayashi 1997, Sakai 1999, Tsang et al. 2008). The same species was identified by GP from photographs of an individual from Laman Bay, the Philippines (AURORA stn CP2720: 14°26'N, 121°47'E, 300 m). It is no surprise the species has been rediscovered in Tosa Bay about 100 km west of the earlier record off Shikoku Island.

Sakai (2016) erected not only a new species for the specimen but also a new genus and a new family, Tosacallianassidae. He compared these taxa with Anacalliacidae Manning & Felder, 1991, Callianassidae Dana, 1852 and Callianopsidae Manning & Felder, 1991 but not with Ctenochelidae or with Gourretiidae Sakai, 1999 which the species also somewhat resembles. The conclusion here, that his species is in fact Ctenocheles balssi, makes his comparisons and purported differences irrelevant.