Megalobrachium roseum ( Rathbun, 1900 ), 2019

Ferreira, Luciane Augusto De Azevedo & Anker, Arthur, 2021, An annotated and illustrated checklist of the porcelain crabs of Panama (Decapoda: Anomura), Zootaxa 5045 (1), pp. 1-154 : 32-35

Megalobrachium roseum ( Rathbun, 1900)

( Fig. 14 )

Porcellana rosea Rathbun 1900: 148 , pl. 8, fig. 3. Porcellanopsis rosea . — Haig 1956: 34. Megalobrachium roseum . — Haig 1960: 225, 227; Gore & Abele 1976: 17; Gore 1982: 7; Rodríguez et al. 2005: 551, pl. 1, fig.

C; Vargas & Cortés 2006: 462; Ferreira & Melo 2016: 177, fig. 1B; Poupin 2018: 147; Hiller & Lessios 2019: 414, fig. 1a;

Ferreira 2019: 61; Mantelatto et al. 2021: 566, fig. 2B.

Material examined. Panama [Caribbean]: 1 female, cl 5.1, cw 4.5 ( MZUSP 33473 ), Bocas del Toro , Isla Colón, mid-way between STRI and Playa Buff , depth 0.3–1 m, fossilised coral platform and adjacent flat with coral rubble and rocks, under large rocks and in coral rock crevices, leg. A. Anker et al., 26.04.2015 .

Previous records from Panama. Gore & Abele (1976); Rodríguez et al. (2005).

Distribution. West Atlantic: Costa Rica, Panama (Bocas del Toro, Punta Galeta, Portobelo), Colombia, Venezuela, E and S Lesser Antilles, Suriname and Brazil from Maranhão to São Paulo ( Rodríguez et al. 2005; Ferreira & Melo 2016; Ferreira 2019; Mantelatto et al. 2021).

Ecology. Rocky intertidal and subtidal, known depth range: 0–50 m; typically under rocks and in crevices of coral rocks and fossilised corals, also on coral reef or among bryozoans, polychaetes and sponges, e.g. in Brazil ( Veloso & Melo 1993; Rodríguez et al. 2005; present study).

Remarks. Megalobrachium roseum is a fairly common porcelain crab, but is usually unnoticed and rarely collected due to its small size and cryptic colouration ( Gore 1982; Hernández et al. 2002). Most specimens are pale to more intense pink ( Fig. 14A, B ), a colour that was also observed by Rathbun (1900) and gave the species its name. However, some are pale-brown (with or without pinkish tinge), possibly due to coating with particles of fine sediment or organic origin ( Fig. 14C, D ; see also Hiller & Lessios 2019).

Figures

FIGURE 14. Megalobrachium roseum (Rathbun, 1900): A, female (cl 5.1 mm, cw 4.5 mm) from Bocas del Toro, Panama (MZUSP 33473), dorsal view; B–D, three different individuals of unknown sex (cl cw indet.) from Portobelo, Panama (not deposited), not to scale with the female in (A) [photographs by AA].