Minuca vocator (Herbst, 1804)

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

Minuca vocator (Herbst, 1804) Figure 3A, B

Recognition characters.

Carapace pentagonal moderately arched; profuse pile on dorsal surface forming a characteristic pattern mostly on hepatic and branchial regions (Fig. 3A ). Dorso-lateral margins well marked even covered by pile, and strongly convergent posteriorly; major and minor pairs of postero-lateral striae clearly visible (Fig. 3A , setae). Front triangular and very wide measuring from 36% to 38% of the front-orbital breadth. Male major claw with manus covered with small tubercles dorsally and frontally and provided with a strong groove on dorsal margin usually filled with dirt; fingers thick and slightly flattened, and a little longer than manus; pollex and dactyl slightly curved forming a gap as wide as the fingers in their base. Exuberant piles on dorsal surface of merus, carpus and manus of all ambulatory legs; these piles can extend to ventral side of manus (Fig. 3B ). Male abdomen somites never fused. Medium-sized crabs, males with CW up to 27.0 mm in a population from Itamambuca mangrove, Ubatuba, southeastern Brazil ( Colpo and Negreiros-Fransozo 2004).

Biological notes.

The species forms one of the densest populations composed by large crabs, and its reproductive period coincides with the rainy period in northern Brazil ( Koch et al. 2005). The southeast populations, however, have continuous reproduction ( Colpo and Negreiros-Fransozo 2003). On the other hand, in impacted mangroves of southeastern Brazil, populations are not dense and crabs are smaller than in other populations ( Bedê et al. 2008). The species prefers muddy substrates ( Colpo and Negreiros-Fransozo 2003; Thurman et al. 2013). Large and well-constructed chimneys at the entrance of burrows were observed in a population from Venezuela, but there is no record of this ornamentation in any other population including those from Brazilian coast ( Crane 1975).

Remarks.

Characteristic pubescence pattern on the carapace and dense piles on dorsal surface of ambulatory legs are the best diagnostic characters for distinguishing it from other Minuca species recorded in Brazil. Another Brazilian fiddler crab that has an exuberant pile on the carapace surface is Leptuca thayeri , easily distinguishable from M. vocator by a very narrow front of the former species (compare Figs 2C and 3A ). Although Melo (1996) considered Santa Catarina State as the southernmost limit of the geographic distribution of the species, currently the species has been reported only in the states from Amapá to São Paulo (Table 1 ).

Figures

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.

Figure 3. Minuca vocator. A carapace with pile forming a typical pattern, dorsal view B third ambulatory leg with pile on dorsal surface of all segments except dactylus (setae), posterior view.