Spermatozoal ultrastructure in three species of the genus Uca Leach, 1814 (Crustacea, Brachyura, Ocypodidae).

Morphological aspects of spermatozoa in marine animals have been used in recent decades as phylogenetic criteria (spermiotaxonomy). This paper presents ultrastructural descriptions of the spermatozoa from Uca maracoani, U. thayeri, and U. vocator. A small portion of the vas deferens of each species was examined under the transmission and scanning electron microscopy. The ultrastructural analysis showed that each spermatophore consists of a varying number of spermatozoa embedded in a dense fibrillar matrix surrounded by a membrane. The spermatozoa of U. maracoani, U. thayeri, and U. vocator are typical of brachyurans. The voluminous acrosome is characterized by three different layers. The postero-lateral surface of the acrosome is cupped by the reduced cytoplasm, and the anterior surface is covered by the operculum. The perforatorium consists of coiled, helicoidal membranous tubules and is continuous with the cytoplasm. The nucleus is composed by uncondensed chromatin and presents several lateral arms distributed over the entire equatorial plane of the cell. The presence of the apical button is a well defined character among all species of the genus Uca, but in U. thayeri it was not observed. The accessory opercular ring can be found in the three studied species, but in distinct development degree. Two centrioles were detected in U. thayeri and U. vocator, but only one was found in U. maracoani. The presence of centrioles in the mature spermatozoa is the first account for the genus Uca upto-date. Considering the ultrastructure of the spermatozoa of U. maracoani, U. thayeri, and U. vocator, we suggest that these three species partially follow the morphological patterns previously described in other Thoracotremata brachyurans. The absence of the apical button in U. thayeri spermatozoa may represent an evolutionary novelty in the genus Uca.

Population and reproductive biology of the crab Uca burgersi (Crustacea: Ocypodidae) in three subtropical mangrove forests

Population and reproductive biology were studied in three populations of the crab Uca burgersi Holthuis, 1967, in the Indaiá, Cavalo and Ubatumirim mangrove forests (Ubatuba, São Paulo State, Brazil). Crabs were collected during low tide (August 2001 through July 2002), by digging the sediment, with a standard capture effort (two persons for 30 min.). Carapace width was measured, and gonad developmental stage was recorded from all specimens. U. burgersi was most abundant in the Cavalo mangrove, where the largest male was found. Juvenile crabs were found year-round at all three sites. However, the ratio of ovigerous females was very low, even null in the Cavalo mangrove. The gonad development rate indicated that U. burgersi was reproducing continuously, but more intensively during spring and summer, with recruitment occurring in winter. The synchrony between the populational and reproductive biology in the three areas showed that local features were not the limiting factors. It is suggested that this species is a habitat generalist.

Estudiamos la biología poblacional y reproductiva de tres poblaciones de Uca burgersi Holthuis, 1967, en los manglares de Indaiá, Cavalo y Ubatumirim (Ubatuba, São Paulo, Brasil). Los cangrejos fueron recolectados por excavación de sedimentos, con un esfuerzo de capturaestándar (dos personas por 30 min), durante la marea baja, entre agosto 2001 y julio 2002. En todos los especimenes se midió la anchura del caparazón y se registró la etapade desarrollo gonadal. Esta especie fue más abundante en Cavalo, donde se halló el macho de mayor tamaño.Encontramos juveniles en los tres sitios, durante todo el período de estudio. Sin embargo, la proporción de hembrasovígeras fue muy baja (nula en Cavalo). Según el desarrollo gonadal, el periodo reproductivo fue continuo allí, pero más intenso durante la primavera y el verano, con reclutamiento en el invierno. La sincronía entre la biologíapoblacional y reproductiva de las tres poblaciones, demuestra que las características locales no fueron los factores limitantes. Se sugiere que esta especie es generalista con respecto al hábitat.