Observation on the occurrence of Uca victoriana von Hagen (Decapoda, Brachyura, Ocypodidae) on the coast of Rio de Janeiro, Brazil.

In Brazil, the family Ocypodidae presents ten representatives of the genus Uca: U. burgersi Holthuis, 1967; U. cumulanta Crane, 1943; U. leptodactyla Rathbun,1898; U. maracoani (Latreille,1802-1803); U. mordax (Smith, 1870); U. rapax (Smith,1870); U. thayeri Rathbun,1900; U. uruguayensis Nobili, 1901; U. victoriana, von Hagen, 1987 and U. vocator (Herbst, 1804). From these, only U. victoriana was not recorded from the state of Rio de Janeiro; its distribution was limited to the state of Espírito Santo (Melo, 1996, 1998). According to Von Hagen (1987), U. victoriana is found in sympatry with U. rapax and appears to have a certain similarity with U. thayeri; besides which, the movements of the chelipeds (waving display) appear very similar in these species. U. victoriana presents a small and convex carapace, with a large front. A shallow pilose depression between the palm and fingers. Opposable margins of fingers with small teeth and with a hiatus between them, larger in the males. The tubercles of the palm present great variation, with a row, or several continuous rows from the carpal cavity to the upper margin. The number and distribution of the tubercles of the intermediary area vary widely. Merus of the ambulatory legs slender in the males and convex in the females. Abdomen with free segments (Melo, 1996, 1998) (Figure 1). The crabs were collected manually in the Itacuruçá mangrove forest (22° 54’ 06” S and 43° 53’ 42” W) (Figure 2) during low tide and were taken to the laboratory of the Marine Biology Station at the Universidade Federal Rural do Rio de Janeiro. They were then sorted, identified, sexed, fixed in 10% formol and preserved in 70% alcohol. Some specimens were deposited in the Museu de Zoologia da Universidade de São Paulo, under the number MZUSP 17.163. A total of 120 specimens were collected from July, 2005 to February, 2006. They include 24 males and 96 females, one of which was ovigerous. The carapace width and length in the specimens of U. victoriana collected in the Itacuruçá mangrove varied from 2.67 to 6.71 mm (4.54 ± 0.85 mm) and 1.75 to 4.0 mm (2.67 + 0.49 mm) in males, and from 2.83 to 7.58 mm (5.27 + 0.89 mm) and 1.92 mm to 4.75 mm (3.42 + 0.56 mm) in females. The ovigerous female was found in November 2005; its carapace width was 6.42 mm and length 4.08 mm. The individuals of U. victoriana were found in the same habitat occupied by U. cumulanta and U. thayeri, in the mud sediments of the mangrove. Von Hagen (1987) found U. victoriana and Thurman II (1987) found U. thayeri in similar habitats. Various studies of species of the genus Uca have shown that differences in sediment and vegetation, as well as the degree of salinity, temperature and exposure 5.4 mm a 6.1 mm b