Scallasis tonkinae ( Grebenyuk, 1975 )

Komai, Tomoyuki, Poore, Gary C. B. & Fujita, Yoshihisa, 2020, Redescription of the poorly known ghost shrimp species, Scallasis amboinae Bate, 1888, review of the genus, and description of a new species from the Ryukyu Islands, Japan (Decapoda: Axiidea: Callianassidae), Zootaxa 4766 (3), pp. 401-420 : 419

Scallasis tonkinae ( Grebenyuk, 1975)

Callianassa (Scallasis) tonkinae Grebenjuk, 1975: 302 –303 , fig. 3.

Callianassa tonkinae .— Sakai 1999: 52.— Sakai 2005: 118.

Trypaea tonkinae .— Sakai 2011a: 411.—? Sakai 2011b: 1119.

Scallasis tonkinae .— Poore et al. 2019: 143.

Not Callianassa tonkinae— Sakai 2002: 503–506, figs 24, 25 = S. andamaniensis ( Sakai, 2010) .

Type locality. Gulf of Tonkin.

Diagnosis. Pleomere 6 1.3 times as long as wide. Telson 0.7 times as long as wide; greatest width 1.3 times posterior width. Maxilliped 3 ischium-merus 3.2 times as long as wide; merus free distal margin transverse, rounded. Female major cheliped ischium lower margin with 4 small spines; merus lower margin with bifid proximal spine; palm 1.2 times as long as carpus.

Distribution. Known with certainty only from the type locality.

Remarks. Placement of Callianassa (Scallasis) tonkinae in Scallasis relies on Grebenjuk’s (1975) figures of the maxilliped 3, pereopod 3 and telson, and to a lesser extent the major cheliped and uropod. The proximal bifid meral spine on the female major cheliped is similar to that seen in male S. caledonica and S. inermis n. sp. The structure of the eyestalk appears unique in Scallasis in the terminal location of the cornea and the lack of a distomesial projection. No dorsal plate, facial spiniform setae or margin tooth were figured on the uropod – we assume they were overlooked.

Dworschak (2007) suggested that Callianassa tonkinae was a junior synonym of Callianassa amboinae . Sakai (2010) referred the material identified as Callianassa tonkinae from the Andaman Sea by Sakai (2002) to a new taxon Trypaea andamaniensis . Sakai (2011b) identified specimens from the Red Sea, 53 m, and Vietnam, 46 m as “ Trypaea ” tonkinae . The Red Sea is far west of other records of this genus but we were unable to examine this material. Grebenyuk’s types are apparently lost; they were not found in the Zoological Museum of the Moscow State University where Grebenyuk worked (I. Marin, pers. comm. 26 Jan 2020).