Scallasis spinophthalma ( Sakai, 1970 )

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 : 417-419

Scallasis spinophthalma ( Sakai, 1970)

( Fig. 10 )

Callianassa (Cheramus) spinophthalma Sakai, 1970: 40–45 , figs 2, 3, 4a, b.

Callianassa spinophthalma . — Sakai 1999: 52.— Sakai 2005: 103.

Cheramus spinophthalmus .— Komai et al. 2002: 39, fig. 7.— Sakai 2011a: 372.

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

Material examined. TRV Toyoshio-maru 2001-11 cruise, stn 10, Sea of Japan off Hagi, Yamaguchi Prefecture, 34°40.00’N 131°10.00’E, 99 m, 5 July 2001, dredge, 1 male (cl 3.3 mm), 1 female (cl 2.8 mm), 5 ovigerous females (cl 3.3–3.6 mm), CBM-ZC 6166; stn 12, off Kawajiri-misaki, Yamaguchi Prefecture, 34°28.40’N 130°52.10’E, 84 m, 7 July 2001, dredge, 1 female (cl 2.8 mm), 4 ovigerous females (cl 2.3–3.5 mm), CBM-ZC 6170.

Type locality. Off Tsushima Islands (34°58'N 129°26.9'E), southern part of the Sea of Japan, at depth of 210 m.

Diagnosis. Pleomere 6 as long as wide. Telson 0.8 times as long as wide; greatest width 1.4 times posterior width. Maxilliped 3 ischium-merus 2.2 times as long as wide; merus free distal margin rounded, slightly produced. Major cheliped strongly sexually dimorphic. Female major cheliped ischium lower margin with 5–7 strong spines; merus lower margin with conspicuous spine at midpoint, followed by few smaller spines proximally; palm subequal in length to carpus. Male major cheliped merus lower margin with trifid spines proximally; palm 1.6 as long as carpus; dactylus with smooth occlusal margin. Minor cheliped ischium lower margin with serration of 5–8 spines; merus lower margin with 1 oblique spine at midpoint. Male pleopod 1 of 2 small articles. Male pleopod 2 biramous. Uropodal endopod anterior margin with minute spine at posterior two-thirds; upper surface with 2 long spiniform setae on midline and 1 submarginal minute spiniform seta proximal to midlength; exopod anterior margin unarmed, upper surface with 1 long submarginal spiniform seta at midpoint.

Distribution. Southern part of the Sea of Japan; at depths of 99– 210 m.

Remarks. Scallasis spinophthalma was originally described on the basis of six female specimens (including three ovigerous specimens) and four detached chelipeds. An ovigerous specimen (cl 4.3 mm) was designated as holotype. The species is notable for the broad maxilliped 3 ischium-merus and the distal margin of the merus much more rounded than in any other congeneric species ( Sakai 1970, fig. 4a; Komai et al. 2002: fig. 9F, G). The species possesses a bi-articulate male pleopod 1 and biramous pleopod 2, more developed than in other species. Komai et al. (2002) did not illustrate female chelipeds, here illustrated ( Fig. 10B, C ); the telson and left uropod are re-illustrated ( Fig. 10A, D ) to show armature (facial spiniform setae and a spine on the uropodal endopod anterior margin) which were overlooked.

Figures

FIGURE 10. Scallasis spinophthalmus (Sakai, 1970). Male (cl 3.3 mm), CBM-ZC 6166: A, telson, dorsal view (setae partially omitted); D, left uropod, dorsal view (marginal setae on rami omitted). Female (cl 3.5 mm), CBM-ZC 6170: B, left major cheliped, lateral view; C, right minor cheliped, lateral view.