Cronius ruber (Lamarck, 1818)

(Fig. 27C, F)

Portunus ruber Lamarck, 1818: 260 .

Trindade specimens. 1 juvenile male (MZUSP 40173), Brazil, off Espírito Santo, Trindade Island, Enseada dos Portugueses, 20°30’17.7”S, 29°18’56.7”W, J.B. Mendonça coll., 18.iv.2014, 10.2 m .

Size of largest male: cl 7 mm, cw 10 mm.

Comparative material examined. Cronius ruber: Brazil: 1 female (MZUSP 4243), São Sebastião, São Paulo, E. Garbe coll., 1915.

Distribution. Amphi-Atlantic. Western Atlantic: New Jersey, Virginia throughout the Gulf of Mexico and Antilles, Colombia, Venezuela, and Brazil (Amapá to Rio Grande do Sul) (Rodriguez 1980; Lemaitre 1981; Williams 1984; Melo 1996; Felder et al. 2009). Williams (1984) cautioned that the record from New Jersey was based on a single male taken in 1974. This is the first record of Cronius ruber from Trindade. Eastern Atlantic: Madeira, Canary Islands (González et al. 2017; Schäfer et al. 2019; Maggio et al. 2021), Cape Verde Islands, Dakar, Senegal (Monod 1956; Manning & Holthuis 1981; Fransen 1991).

Ecological notes. Inhabits hard- (rocks, coralline reefs, rubbles, sublittoral caves) and soft bottoms (organogenic and, occasionally sandy bottoms, sand-seagrass meadow including Thalassia testudinum) between the tide mark to 105 m (Coelho & Ramos 1972; Heck 1977; González et al. 2017). Cronius ruber has been reported to use colonies of the bryozoan Schizoporella unicornis as a feeding site (Ales et al. 2013); juveniles were found in association with the sponge Amphimedon viridis (see Alves et al. 2012c). In Trindade, C. ruber was found in sandy bottom, close to rocks. A West African female was found to carry 474,400 eggs (González et al. 2017). Ovigerous females are parasitized by Sacculina (Rodríguez 1982) . Freitas et al. (2017) reported that the grouper Epinephelus morio (Valenciennes) feeds more heavily on crustaceans, particularly on C. ruber in the Abrolhos Bank (Bahia, Brazil); the grouper E. striatus, the mutton snapper Lutjanus analis (Cuvier) and Octopus vulgaris are also known to prey upon C. ruber (Randall 1967; Anderson et al. 2008; Begossi et al. 2012).

Remarks. Ng & Nyberg (2013) showed that Portunus ruber Lamarck, 1818, is a junior synonym of Cancer thunborgii Euphrasén, 1795, and clarified that P. ruber should be conserved by reversal of precedence under Art. 23.9.1 of the ICZN (1999: 27).

Manning & Holthuis (1981) discussed the morphological differences between the west- and east Atlantic populations of C. ruber (Fig. 27C, F) and mentioned that the name C. millerii (A. Milne-Edwards, 1867) is available for the west African population if, ultimately, it proves to be taxonomically distinct.