An illustrated key to the fiddler crabs (Crustacea, Decapoda, Ocypodidae) from the Atlantic coast of Brazil Author Masunari, Setuko Laboratory for Crustacean Research UFPR, Department of Zoology, Federal University of Parana, Curitiba, Parana State, Brazil set_mas@yahoo.com.br Author Martins, Salise Brandt Laboratory for Crustacean Research UFPR, Department of Zoology, Federal University of Parana, Curitiba, Parana State, Brazil Author Anacleto, Andre Fernando Miyadi Laboratory for Crustacean Research UFPR, Department of Zoology, Federal University of Parana, Curitiba, Parana State, Brazil text ZooKeys 2020 943 1 20 http://dx.doi.org/10.3897/zookeys.943.52773 journal article http://dx.doi.org/10.3897/zookeys.943.52773 1313-2970-943-1 2E2EAD47EC1A49FCAA9B857C29E283D6 2445E5941B585EE6B56E114E62102FB5 Minuca burgersi (Holthuis, 1967) Figures 1B , 4B , 7B , 8C, D Recognition characters. Carapace pentagonal moderately arched in the anteroposterior direction and dorsal surface without pile (Fig. 8C ). Dorso-lateral margins well-marked and converging posteriorly; major and minor pairs of postero-lateral striae clearly visible (Fig. 8C ). Front triangular and very wide making up from 36% to 41% of the front-orbital breadth (Fig. 1B ). Male major claw manus covered by small tubercles and provided with a strong groove (sometimes filled with dirt) on dorsal surface following the dorsal margin; fingers thick and slightly flattened; dactyl little longer than manus; pollex and dactyl curved forming a large gap (Fig. 8D ). First three ambulatory legs with pile (= woolly pubescence) limited to dorsal surface of carpus and manus (Fig. 4B , setae), absent in ventral margin; all ambulatory legs with narrow merus and dorsal margin almost strait; last pair of ambulatory legs without piles and merus less than two 1.5 times wider than respective carpus in its maximum breadth (Fig. 7B ). Male abdominal segments never fused. Medium-sized species and one of the smallest in the genus; males' carapace width (CW) up to 19.0 mm in a population from Fortaleza, CE, Brazil ( Crane 1975 ). Biological notes. The species reproduces year-round in the population of Ubatuba, southeastern Brazil ( Benetti et al. 2007 ). It occurs in oligohaline and mesohaline areas and on sandy substrate although in low densities ( Masunari 2006 ; Thurman et al. 2013 ). Remarks. The species is morphologically close to its congeners M. rapax and M. mordax ; the distinguishing characters among these species are treated in the subsequent items.