Euryplax nitida Stimpson, 1859

CASTRO, PETER & NG, PETER K. L., 2010, Revision of the family Euryplacidae Stimpson, 1871 (Crustacea: Decapoda: Brachyura: Goneplacoidea), Zootaxa 2375 (1), pp. 1-130 : 47-49

Euryplax nitida Stimpson, 1859

( Figs. 16A–F ; 17A–G ; 18A, B ; 20A–C ; 39A, B )

Euryplax nitidus Stimpson, 1859: 60 [Florida Keys]. — Smith 1870: 162 [Florida, Gulf of Mexico].

Euryplax nitida Stimpson 1871: 150 [Florida Keys]. — Rathbun 1918: 34 [in key], 34, fig. 11, pl. 7 [Florida, Puerto Rico]; 1933: 78, fig. 69 [ Puerto Rico]. — Boone 1927: 14 [ Cuba]. — Williams 1965: 202, fig. 185; 1984: 431 [in key], 432, fig. 343 [Atlantic coast of the U.S.]. — Guinot 1969b: 512 [discussion], figs. 39, 41, 47, 56, 57; 1971: 1080 [in list]; 1984: pl. 1, figs. F, G. — Felder 1973: 70 [in key], pl. 10, fig. 1 [in list] [Gulf of Mexico]. — Powers 1977: 113 [in list] [Gulf of Mexico]. — Camp 1998: 148 [in list]. — Karasawa & Kato 2003b: 130 [in list]. — McLaughlin et al. 2005: 257 [in list]. — Hernández-Ávila et al. 2007: 35, 40 [in list] [ Venezuela]. — Ng et al. 2008: 78 [in list]. — Coelho et al. 2008: 12 [in list] [ Brazil].

Type material. Lost; type locality: Florida, Florida Keys.

Neotype of Euryplax nitidus Stimpson, 1859 : male, 7.1 mm × 11.3 mm ( UF 15166 ; Figs. 16 , 39A ); type locality: Florida, Gulf of Mexico, west of St. Petersburg , 27.4815°N, 82.8872°W, 0–12 m.

Material examined. Florida. Gulf of Mexico, west of St. Petersburg , 27.4815°N, 82.8872°W, Capetown dredge, 0–12 m, G. Paulay coll., 12.11.2007: male neotype (here designated), 7.1 mm × 11.3 mm ( UF 15166 ); male, 4.4 mm × 7.0 mm ( UF 15168 ) .

Gulf of Mexico, Marco Beach, L. B. Holthuis coll., 12.09.1960: 2 males, 7.2 mm × 10.4 mm, 4.2 mm × 5.6 mm, 1 pre-adult female, 3.9 mm × 5.8 mm, 1 female, 4.2 mm × 6.6 mm ( RMNH D 15769) .

Off southern Florida, 25°17.32’N, 81°39.49’W, 13 m, Suncoaster , 10.12.1983: 1 female ( USNM 276579 ) .

Colombia. Off Bahía Honda , stn. A15–39, 5– 6 m, 8.04.1939: 3 males, 6.2 mm × 9.6 mm, 6.3 mm × 9.5 mm, 7.5 mm × 11.3 mm, 2 ovigerous females, 6.0 mm × 8.8 mm, 6.4 mm × 9.8 mm ( LACM); 16–18 m, 8.04.1939: 12 males, 1 pre-adult female, 7 females, 7 ovigerous females ( LACM) .

SW of Cape de la Vela, stn. A1339, CN 106, 5– 7 m, 8.04.1939: 1 male, 6.4 mm × 10.2 mm ( LACM); 18– 24 m, 2 males, 2 pre-adult females, 3 ovigerous females ( LACM) .

Venezuela. North of Coche I., stn. A32–39, 35– 60 m, 8.04.1939: 1 female ( LACM) .

North of Margarita I., stn. A42–39, 21.04.1939: 1 female, 1 ovigerous female ( LACM) .

Cubagua I., stn. A28–39, 4 m, 15.04.1939: 1 pre-adult female ( LACM).

Trinidad. Gulf of Paria near San Fernando, 4.5 m, Shell Expedition , 02.05.1952: 1 male ( RMNH D 9764 ) .

Curaçao. Prof. Boeke coll., 26.05.1905: 1 ovigerous female, 10.3 mm × 16.2 mm ( RMNH D 2263 ) .

Brazil. Dertero (?), M. Muller leg.: 1 male, 13.9 mm × 23.2 mm, 1 male, 9.8 mm × 16.4 mm (MNHN- B8732) .

Santos, 20.04.1961, L. R. Tommasi leg.: 1 female ( RMNH D 18755) .

Unknown location, identified as “ Frevillea rosaea ”: 1 male, 28.3 mm × 16.9 mm (NHM 1850.32).

Diagnosis. Outer orbital angle typically reduced, acuminate ( Figs. 16A ; 17A, B, E ). Dorsal surface of cheliped merus with depression near anterior margin.

Remarks. Euryplax nitida , which is Western Atlantic in distribution, is very close to E. polita , a species that is restricted to the Tropical Eastern Pacific region. Both species may be distinguished from each other by the shape of the outer orbital angle: typically reduced and acuminate in E. nitida ( Figs. 16A ; 17A, B, E ; Guinot 1969b: fig. 41) but more expanded anteriorly and broader in E. polita ( Fig. 18C ; Guinot 1969b: fig. 1). The shape of the anterolateral teeth varies in both species, varying from obtuse to slender. The dorsal surface of the cheliped merus of E. nitida has a depression near its anterior margin, which is absent in E. polita . In the male neotype (7.1 mm × 11.3 mm; UF 15166) a triangular, setose tooth is located at the proximal margin of the depression. The depression is referred to as a “deep pit” by Rathbun (1918: 34) and “fosette” by Guinot (1969b: 512). The eye peduncles are noticeably shorter in E. nitida ( Fig. 16A, C ) than in E. polita ( Fig. 18C ), and the suborbital border is nearly straight, with two small lobes in E. nitida ( Figs. 16C ; 17E ; 18A ), but with two lobes folded ventrally in the largest individuals of E. polita .

Some of the characters given by Rathbun (1918: 34, 36) to differentiate between the two species (i.e. carapace anterolateral borders converging anteriorly and fingers with white tips in E. nitida ; anterolateral borders parallel and fingers with brown tips) do not agree with all the material examined. In fact, the anterolateral borders of the carapace are parallel in the specimens of E. nitida examined ( Figs. 16A ; 17A, B ) as well as in the photograph given by Rathbun (1918: pl. 7) but they converge in at least some specimens of E. polita ( Fig. 18C ). The photograph of the holotype of E. polita given by Guinot (1969b: fig. 1) nevertheless shows straight anterolateral borders.

The type material of Stimpson’s species, as with most of his material (see Evans 1967; Deiss & Manning 1981; Manning 1993; Manning & Reed 2006) is almost certainly lost. In the interest of long-term nomenclatural stability, we hereby designate a male neotype for Euryplax nitidus Stimpson, 1859 (7.1 mm × 11.3 mm; UF 15166; Figs. 16 ; 39A ). It was collected in the Gulf of Mexico off St. Petersburg, Florida, approximately 358 km north of the Florida Keys, the type locality of Stimpson’s species.

Colour pattern. Irregular dark gray spots across tan to light yellow dorsal surface of carapace; irregular spots on chelipeds, dark purple blotch at the base of each finger, and banded ambulatory legs (male neotype, UF 15166) ( Fig. 39A ). Spots were relatively smaller in a smaller male (UF 15168) ( Fig. 39B ).

Distribution. Western Atlantic from North Carolina, Bermuda and Gulf of Mexico to southern Brazil ( Coelho et al. 2008). Depth: shallow subtidal to 90 m ( Powers 1977).

Figures

FIGURE 16. Euryplax nitida (Stimpson, 1859); A–F, male neotype of Heteroplax nitidus Stimpson, 1859 (7.1 mm × 11.3 mm) (UF 15166), Florida, Gulf of Mexico, west of St. Petersburg. A, overall view; B, outer surface of chelae; C, frontal view showing orbits and antennae; D, anterior portion of male thoracic sternum and abdomen; E, sternal protection of penis; F, posterior portion of male thoracic sternum and abdomen. Abbreviations: a1–a3, a6 = male abdominal somites 1, 2, 3, 6, respectively; cx5 = coxa of fifth pereopod (P5); es7 = episternite 7; G1 = first male pleopod; mg = median groove; p = penis; s4–s8 = thoracic sternites 4 to 8, respectively; t = telson.

FIGURE 17. Euryplax nitida Stimpson, 1859; A, C, G, male (7.2 mm × 10.4 mm) (RMNH D 15769), Florida, Marco Beach; B, D, female (USNM 276579), Gulf of Mexico, off Florida; E, F, male (13.9 mm × 23.2 mm) (MNHN-B8732), Brazil, Dertero (?). A, B, dorsal views of carapaces; C, third maxillipeds; D, anterior portion of male sterno-abdominal cavity and G1; E, anterior portion of male thoracic sternum and abdomen; F, posterior portion of male thoracic sternum and abdomen; G, posterior portion of male sterno-abdominal cavity and G2. Abbreviations: a1–a3 = male abdominal somites 1, 2, 3, respectively; cx5 = coxa of fifth pereopod (P5); es7 = episternite 7; G1 = first male pleopod; G2 = second male pleopod; mg = median groove; p = penis; pb = press-button of male abdominal-locking mechanism; s4–s8 = thoracic sternites 4 to 8, respectively.

FIGURE 18. A, B, Euryplax nitida Stimpson, 1859; A, female (USNM 276579), Gulf of Mexico, off Florida, ventral view of carapace; B, female (10.1 mm × 7.1 mm) (LACM), Colombia, Atlantic coast, ventral view of carapace; C, D, Euryplax polita Smith, 1870; male (18.9 mm × 33.8 mm) (LACM), Perú, Tumbes; E, F, Frevillea hirsuta (Borradaile, 1916); E, male lectotype of Goneplax hirsutus Borradaile, 1916 (10.5 mm × 15.2 mm) (NHM 1917.1.29.148–9); F, female paralectotype of Goneplax hirsutus Borradaile, 1916 (12.0 mm × 17.8 mm) (NHM 1917.1.29.148–9). A, ventral view; B, D, female sterno-abdominal cavity; C-F, overall view; D; male sterno-abdominal cavity. Abbreviations: a3 = male abdominal somite 3; G1 = first male pleopod; G2 = second male pleopod; pb = press-button of male abdominallocking mechanism; s4–s8 = thoracic sternites 4 to 8, respectively; v = vulva. Photo credits: B, C, D by J. Martin (LACM); E, F by P. Crabb (NHM).

FIGURE 20. Gonopods of Euryplax and Frevillea species. A–C, Euryplax nitida Stimpson, 1859; A, B, G1; C, G2 (after Guinot 1969b: figs. 56, 57); D–F, Frevillea hirsuta (Borradaile, 1916): D, E, G1; F, G2 (after Guinot 1969b: figs. 58, 59).

FIGURE 39. Colours in life. A, Euryplax nitida Stimpson, 1871; male neotype (7.1 mm × 11.3 mm) (UF 15166), Gulf of Mexico; B, Euryplax nitida Stimpson, 1871; male (4.4 mm × 7.0 mm) (UF 15168), Gulf of Mexico; C, Psopheticoides sanguineus Sakai, 1969, male (22.2 mm × 26.7 mm) (MNHN-B29728), Philippines, Bohol, Panglao; D, Trissoplax dentata (Stimpson, 1858), male (6.2 mm × 8.3 mm) (NHM), Thailand, Andaman Sea; E, Trissoplax dentata (Stimpson, 1858), young male, not preserved, Singapore, Changi; F, Trissoplax dentata (Stimpson, 1858), female (8.7 mm × 11.5 mm) (ZRC 2000.2240), Singapore. Photo credits: A, B by Florida Museum of Natural History (UF); D by P. F. Clark (NHM).