Kasagia, Forges, Bertrand Richer De & Ng, Peter K. L., 2007

Forges, Bertrand Richer De & Ng, Peter K. L., 2007, On a new genus and new species of deep-water spider crab from the Philippines (Crustacea, Decapoda, Brachyura, Majidae), Zootaxa 1644, pp. 59-68 : 59-60

Kasagia , new genus

Diagnosis. Carapace ovoid. Dorsal face almost round, ornamented with fungiform granules; regions weakly defined. Ocular peduncule short, eye rounded, totally concealed orbit when retracted. Front with 2 sharp pseudorostral spines, oval in cross-section. Supra-ocular margin forming a complete eave overlapping post-ocular spine; intercalated spine absent. Hepatic plate triangular. Basal antennal article triangular, formed by fused first 2 articles. Male cheliped very long, covered with setae; carpus short with spines; propodus long; fingers thin, tips crossing when closed. Ambulatory legs short, with merus carinated on upper part; other articles covered by setae. Male sternites 2–4 relatively wide. Abdomen with 6 free segments and telson. G1 with distal part dilated.

Etymology. The genus name is derived from Balicasag (“the island of the broken crab)”, the place where the crab was found, “kasag” meaning crab in Tagalog. Gender feminine.

Remarks. The new genus, Kasagia , has affinities with Eurynome Leach, 1814 , and its allies. Eurynome was established for E. aspera ( Pennant, 1777) from the Atlantic and Mediterranean, but over the years, 11 species have been attributed to this genus at one time or another (see Griffin 1964; Griffin & Tranter 1986). Griffin and Tranter (1986) reviewed the genus and separated its members into three genera: Eurynome Leach, 1814 , sensu stricto, Choniognathus Rathbun, 1932 , and Seiitaoides Griffin & Tranter, 1986 . Eurynome was restricted to E. aspera ( Pennant, 1777) (type species) (= E. scutellata Risso, 1827 , E. boletifera Costa, 1838 , E. longimana Stimpson, 1858 , E. aspera var. acuta ( A. Milne-Edwards & Bouvier, 1900) , E. bituberculata Griffin, 1964 , E. erosa A. Milne-Edwards, 1873 , E. parvirostris Forest & Guinot, 1966 , and E. spinosa Hailstone, 1835 . Choniognathus was redefined to accomodate C. elegans ( Stebbing, 1921) , C. granulosus ( Baker, 1906) , C. reini ( Balss, 1924) (= C. koreensis Rathbun, 1932 , type species), and C. verhoeffi ( Balss, 1929) . In Seiitaoides Griffin & Tranter, 1986 , only two species were included, S. orientalis ( Sakai, 1961) (type species) and S. stimpsonii ( Miers, 1884) .

Kasagia differs from Eurynome in that the carapace is covered by numerous small flattened or round granules except for a few small fungiform granules on the anterior and lateral regions ( Figs. 1 , 2 A) (versus numerous large fungiform and plate-like granules in Eurynome , with some fusing to form large elevated plates, Figs. 2 B), the anterior part of the thoracic sternum, notably around the margins of the sterno-abdominal cavity, is unornamented ( Fig. 3 C) (versus with granules and with the margin of the sterno-abdominal cavity lined with large raised plates, Fig. 3 D), the ambulatory legs have prominent and complete carinated meri ( Fig. 2 A) (versus margins of meri serrated or uneven in Eurynome , Fig. 2 B), the pseudorostral spines are ovoid in cross-section (versus C-shaped in Eurynome ), the base of the fused basal antennal article has a lateral projection which extends anteriorly towards the post-orbital tooth ( Fig. 3 C) (versus without any projection in Eurynome , Fig. 3 D), the supra-orbital eave overlaps the post-ocular tooth ( Fig. 3 A) (versus supra-orbital eave separated from the post-ocular tooth by a large gap in Eurynome , Fig. 3 B, see also Hartnoll 1961: 175, fig. 2), the adult male chelipeds are extremely long, being approximately three times the carapace length and covered with short spines and numerous short, stiff setae ( Figs. 2 B, 4D) (versus at most two times carapace length with large lobiform teeth and scattered setae or almost glabrous, Figs. 2 B, 4D), and the G1 is dilated distally ( Fig. 5 B, C) (versus with a prominent hook-like projection subdistally, Fig. 5 A). With regards to the gap between the supra-orbital eave and post-ocular tooth, an intercalated spine is present in E. bituberculata (see Griffin 1964: 198, fig. 2), but in E. aspera , this spine is small ( Fig. 2 B, Hartnoll 1961: 179, 5a, b).

Kasagia resembles Choniognathus in having numerous granules and two pseudorostral spines separated by a U-shaped hiatus. As in Choniognathus there is no preocular spine. However, Kasagia is very different from Choniognathus in that it has a supraorbital eave which overlaps the post-ocular spine but lacks an intercalated spine ( Fig. 3 ) (versus with a distinct intercalated spine in Choniognathus , see Griffin 1965: 30, Fig. 4 ), the adult male chelipeds are approximately three times the carapace length, covered with short spines and numerous short, stiff setae ( Figs. 2 A, 4C) (versus at most two times carapace length with large teeth or spines and scattered setae) and the G1 is curved with a prominent expansion in the distal third and not setose ( Fig. 5 B, C) (versus G1 simple, straight with numerous setae in Choniognathus , see Griffin & Tranter 1986: 204, Fig. 69c, d).

Compared to Seiitaoides , Kasagia differs in that the dorsal surface of the carapace only has small squamiform granules ( Fig. 1 , 2 A) (versus prominent large plates in Seiitaoides, Griffin 1970 ; Griffin & Tranter 1986), a supraorbital eave which overlaps the post-ocular spine but does not have an intercalated spine ( Fig. 2 A) (versus with a distinct intercalated tooth in Seiitaoides , see Griffin 1970; Griffin & Tranter 1986), and the G1 has an expanded distal part and with only sparse setae ( Fig. 5 B, C) (versus evenly straight with setae in Seiitaoides , see Griffin & Tranter 1986: 204, Fig. 69e, f).

Figures

FIGURE 1. Kasagia arbastoi, new species, male paratype (11.2 x 7.9 mm) (MNHN). Colour in life.

FIGURE 2. Overall dorsal views. A, Kasagia arbastoi, new species, male holotype (12.1 x 8.7 mm) (NMCR); B, Eurynome aspera, male (12.4 x 11.5 mm) (ZRC 1988.665).

FIGURE 3. Kasagia arbastoi, new species. A, B, dorsal carapace view; C, D, ventral carapace view. A, C, Kasagia arbastoi, new species: A, male holotype (12.1 x 8.7 mm) (NMCR), C, male paratype (12.6 x 9.2 mm) (ZRC); B, D, Eurynome aspera, male (12.4 x 11.5 mm) (ZRC 1988.665).

FIGURE 5. Left G 1 s. B, C, Kasagia arbastoi, new species, male paratype (12.6 x 9.2 mm) (ZRC); A Eurynome aspera, male (12.4 x 11.5 mm) (ZRC 1988.665). Scales = 5.0 mm.

FIGURE 4. A, B, buccal cavern and face; C, D, outer view of chela. A, C, Kasagia arbastoi, new species, male paratype (12.6 x 9.2 mm) (ZRC); B, D, Eurynome aspera, male (12.4 x 11.5 mm) (ZRC 1988.665).