Uca maracoani (Latreille, 1802-1803)

Masunari, Setuko, Martins, Salise Brandt & Anacleto, Andre Fernando Miyadi, 2020, An illustrated key to the fiddler crabs (Crustacea, Decapoda, Ocypodidae) from the Atlantic coast of Brazil, ZooKeys 943, pp. 1-20 : 1

Uca maracoani (Latreille, 1802-1803) Figures 1A , 2A, B

Recognition characters.

Carapace trapezoidal moderately arched and naked dorsal surface, without any ornaments. Dorso-lateral margins well marked, long and weakly converging posteriorly; postero-lateral striae absent (Fig. 2A ). Front spatulate and very narrow making up ca. 4% of front-orbital breath (Fig. 1A ). Male major claw extremely large, with flat fingers and ornamented with tubercles, granules and small patches; narrow gap (Fig. 2B ). Ambulatory legs without pile. Male abdomen somites distinct. Large fiddler crab: male CW up to 45.0 mm and female 40.2 mm in Paraty Bay, Rio de Janeiro state, southeastern Brazil ( Hirose and Negreiros-Fransozo 2008).

Biological notes.

The species reproduces year-round in northern ( Azevedo et al. 2016), northeastern ( Silva et al. 2016), southeastern ( Hirose and Negreiros-Fransozo 2008) and southern ( Benedetto and Masunari 2009) regions, but only during the dry season in northern region ( Koch et al. 2005). Well-established populations are typically recorded in muddy substrates of polyhaline areas of estuaries, where no other fiddler crab species was seen sharing this space ( Masunari 2006). Genetic analysis revealed a lack of discernible genetic subdivision among populations of Uca maracoani along Brazilian coast; however, geometric morphometric technique showed statistically significant morphological differentiation that would indicate a strong phenotypic plasticity ( Wieman et al. 2014).

Remarks.

In the field, these crabs are unmistakable recognizable by the flattened fingers of the male major claw. Furthermore, they are visibly larger than any other Brazilian fiddler crab species.

Figures

Figure 1. Carapace, frontal view. A Uca maracoani: spatulate and narrow front (seta) B Minuca burgersi: triangulate and wide front (seta).

Figure 2. Uca maracoani. A carapace with bare surface, dorsal view B male major claw with flat fingers, frontal view. Leptuca thayeri C carapace mostly covered with pile (seta) D male major claw with cylindrical fingers, frontal view.