Scyramathia umbonata (Stimpson, 1871)

Lee, Bee Yan, Richer De Forges, Bertrand & Ng, Peter K. L., 2020, Revision of the deep-water spider crab genus, Scyramathia A. Milne-Edwards, 1880, with the description of a new species from the Mediterranean and notes on Rochinia A. Milne-Edwards, 1875, and Anamathia Smith, 1885 (Crustacea, Decapoda, Brachyura, Epialtidae), Zoosystematics and Evolution 96 (2), pp. 537-569 : 537

Scyramathia umbonata (Stimpson, 1871) Figs 11A-C , 14E

Scyra umbonata Stimpson 1871: 115 (type locality: off Sand Key, Florida).

Scyra umbonata : A. Milne-Edwards 1875 [in 1873-1880]: 87-88; A. Milne-Edwards 1880 [in 1873-1880]: pl. 31A fig. 5-5b; A. Milne Edwards 1880c: 2; Sars, 1885: 6 (list), 7 (list), 274 (list); Smith 1886: 626[22 on separate]

Scyramathia umbonata : A. Milne-Edwards 1880a: 356; A. Milne-Edwards 1880b: 277; A. Milne-Edwards and Bouvier 1923: 381; Tavares and Santana 2018: 204 (list), Figs 1 , 12C , 13A, B .

Anamathia umbonata : Rathbun 1894: 61-62, pl. 1 Figs 1 - 3 ; Faxon 1895: 10.

Rochinia umbonata : Rathbun 1925: 210 (key), 222, 223, text-fig. 85, pl. 72, pl. 73 fig. 1; Bullis and Thompson 1965: 12 (list); Williams et al. 1968: 61, fig. 16; Takeda 1983: 135; Williams 1984: 322 (key), 323-325, figs 258, 260c; Abele and Kim 1986: 42, 172 (key); Griffin and Tranter 1986: 175 (list); Soto 1991: 628 (table), 632 (list), 633 (list), 634, 636 (list); Tavares 1991: 161 (list), 164; Poupin 1994: 43, 44, pl. 4 fig. g; Nizinski 2003: 128; McLaughlin et al. 2005: 253 (list); Wicksten and Packard 2005: 1762 (list); Casadío et al. 2005: 159 (list), 160; Ng and Richer de Forges 2007: 63 (list); Ng et al. 2008: 106 (list); Felder et al. 2009: 1078 (list); Pettan 2013: 72-80, 87 (key), figs 14a, b, 17h, 18b, 19b, 20b, 28a-d, 29a-c; Pettan and Tavares 2014: 306 (list), fig. 1; Tavares et al. 2016: 1065-1069, figs 1-6.

Rochinia confusa Tavares 1991: 161 (list), 162-165, fig. 1A-C, 5A, pl. 1 A-D (type locality: off Rio de Janeiro, 23°46'S, 42°09'W, Brazil); De Melo 1996: 266 (key), 267, unnumbered in-text fig.; Casadío et al. 2005: 158 (list); Ng and Richer de Forges 2007: 63 (list); Ng et al. 2008: 105 (list); Pettan 2013: 21-26, 87 (key), figs 7a, b, 16a, 18a, 19a, 20a; Pettan and Tavares 2014: 305 (list), fig. 1. (For the remaining Neotropics literature, see Tavares et al. 2016).

Material examined.

Paratype of Rochinia confusa Tavares, 1991: 1 ♂ (8.0 × 5.2 mm) ( MNHN-IU-2014-19836 [= MNHN-B24570]), stn 54, Brazil, 19°36'S, 38°53'W, coll. TAAF/MD55, 2 June 1987. Other material: 1 ♀ (36.7 × 27.9 mm) ( NSMT-Cr7178), off Suriname, 7°47'N, 54°08'W, 60 m, coll. 1980.

Diagnosis.

Carapace pyriform, covered with short setae. Pseudorostral spine short, diverging. Supraorbital eave fused to carapace with sharp preorbital spine; postorbital lobe and hepatic spine fused, forming a L-shape plate-like structure, pointing upwards; plate-like structure not formed on juvenile specimens. Carapace with raised plates: 1 hepatic plate curved, pointing upwards, 1 short mesogastric granule above 1 oblong mesogastric plate, 1 oblong cardiac plate, 1 large epibranchial plate, 1 mesobranchial plate, 1 posterior blunt spine, 1 lateral branchial plate curved upwards (Fig. 11A ). Plates less distinct on juvenile specimens. Antennal flagellum equal to or slightly longer than pseudorostral spines. Basal antennal article with convex outer margin, with blunt distal angle of article. Buccal frame covered by third maxilliped, distal angle of buccal frame raised, distinct. Pterygostomial region plate-like with 3 or 4 granules on outer margin (Fig. 11B ). Chelipeds slender, propodus longer than fingers, slightly carinate. Ambulatory legs slender; merus cylindrical; male P2 merus length approximately 0.7 times carapace length, female P2 merus length 0.6-1.0 times carapace length, male P2 merus length approximately 9.0 times width, female P2 merus length 9.5-12.3 times width; male P5 merus length approximately 04 times carapace length, female P5 merus length 04-0.6 times carapace length, male P5 merus length approximately 4.4 times width, female P5 merus length 4.1-6.9 times width (cf. Rathbun 1925: pl. 72, 73 fig. 1; Figs 11A , 14E ). Male thoracic sternum wide, concave on sternites 1-4; regions well defined; sternites 3, 4 widest, lateral margins slightly constricted. Male pleon, telson triangular; surface of somites smooth (Fig. 11E ). G1 straight with flattened sharp tip (cf. Tavares and Santana 2018: fig. 13A, B).

Remarks.

Scyramathia umbonata was originally described as a species of Scyra by Stimpson (1871) from off Sand Keys in Florida. Stimpson (1871) provided measurements for one male specimen but did not indicate if he had more material. It was transferred to Scyramathia by A. Milne-Edwards (1880a), and Rathbun (1894) subsequently referred it to Anamathia . Rathbun (1925) later transferred the species to Rochinia when she synonymised the genera. The type material for the S. umbonata is probably no longer extant ( Tavares et al. 2016).

Tavares et al. (2016) discussed the taxonomy of S. umbonata at length (see also Tavares and Santana 2018) and synonymised Rochinia confusa Tavares, 1991, under S. umbonata , stating that R. umbonata undergoes drastic changes in morphology as it grows, with more distinct plates being present on larger sized specimens. This is the same pattern as seen in S. carpenteri and S. hertwigi . Tavares and Santana (2018) later transferred it back to Scyramathia . There is no need to redescribe or figure this species as the detailed study and figures of this species by Tavares et al. (2016) and Tavares and Santana (2018) are quite sufficient. For these reasons, a neotype is also not needed for this species for the time being.

Distribution.

Scyramathia umbonata is recorded from the North Carolina to Gulf of Mexico (United States of America), Nicaragua, Caribbean Island, and Brazil ( Tavares et al. 2016).

Figures

Figure 1. Rochinia gracilipes A. Milne-Edwards, 1875, paralectotype male [dry] (20.0 x 15.0 mm) (MNHN-IU- 2000 - 4460 [= MNHN-B 4460]), Cap. Corrientes. A. overall dorsal view; B. overall ventral view; C. lateral view of carapace.

Figure 3. Illustration of Scyramathia carpenteri (Norman, in Thomson 1873), " sandy chalk of Holtenia ground ", overall dorsal view. (After Norman, in Thomson 1873: fig. 35).

Figure 11. A-C. Scyramathia umbonata (Stimpson, 1871), female (36.7 x 27.9 mm) (NSMT-Cr 7178), off Suriname; D-F. Rochinia confusa Tavares, 1991, paratype male (8.0 x 5.2 mm) (MNHN-IU- 2014 - 19836 [= MNHN-B 24570]), Brazil. A, C. overall dorsal view; B, E. overall ventral view; C, F. lateral view of carapace.

Figure 12. Colour in life of Scyramathia tenuipes sp. nov., holotype male (33.9 x 26.3 mm) (ICMD 288), Mediterranean Sea (Credits: MacPherson E & Abello P).

Figure 13. Scyramathia tenuipes sp. nov., holotype male (33.9 x 26.3 mm) (ICMD 288), Mediterranean Sea. A. overall dorsal view; B. overall ventral view; C. lateral view of carapace.

Figure 14. Dorsal view of P 5. A, B. Scyramathia carpenteri (Norman, in Thomson 1873); A. male (41.3 x 34.0 mm) (NHM 1983.449), North Sea; B. ovigerous female (35.8 x 29.0 mm) (NHM 1978.99), Atlantic Ocean; C, D. S. hertwigi Doflein, in Chun 1900; C. male (34.6 x 27.3 mm) (NHM 1924.7.19.1 - 3), South Africa; D. female (24.5 x 18.4 mm) (SAM-A 47872), South Africa; E, S. umbonata (Stimpson, 1871), female (36.7 x 27.9 mm) (NSMT-Cr 7178), off Suriname; F-J. S. tenuipes sp. nov.; F. holotype male (33.9 x 26.3 mm) (ICMD 288), Mediterranean Sea; G. paratype male (29.7 x 22.0 mm) (ICMD 000707), Mediterranean Sea; H. paratype male (32.0 x 25.4 mm) (ZRC 2019.1636), Mediterranean Sea,; I. paratype ovigerous female (31.2 x 24.6 mm) (ICMD 000708), Mediterranean Sea,; J. paratype ovigerous female (32.2 x 25.8 mm) (ZRC 2019.1635), Mediterranean Sea.