Valter José Cobo

Relative growth and sexual maturity of the spider crab, Mithrax tortugae Rathbun, 1920 (Brachyura, Mithracidae) on a continental island off the southeastern Brazilian coast

Relative growth can be understood as a morphometric relationship of body parts with the body as a whole, described by a mathematic equation. This study provides information on the patterns of relative growth of Mithrax tortugae from Vitoria Island, southeastern Brazilian coast (23°44′04″S 45°01′35″W). Crabs were obtained from monthly collections by hand during SCUBA diving, between January 2004 and February 2007. A total of 168 crabs was obtained, 64 males and 104 females. Regression analysis was performed among carapace width (CW), as the independent variable, and carapace length (CL), abdomen width (AW), height high and length of the propodus (PH and PL), and gonopod length (GL) as dependent variables, using the power function y = a x b . Young males showed positive allometry with regard to gonopod growth. Abdomen growth of juvenile females was also positively allometric. The growth patterns recorded for M. tortugae are associated with the species reproductive strategy, i.e., preparation of body parts involved in gamete transfer and egg clutch storage, like the male gonopods and the female abdomen. According to the results obtained, morphological maturity is attained at 12.95 mm CW for males and at 22.40 mm CW for females. The general patterns shown by M. tortugae are similar to the model adopted for Brachyura in general. Crescimento relativo pode ser entendido como a analise das relacoes entre dimensoes de partes do corpo em funcao do corpo como um todo, descrita por uma equacao matematica. Este estudo fornece informacoes sobre os padroes de crescimento relativo do Mithrax tortugae , de uma populacao da Ilha da Vitoria, sudeste do litoral brasileiro (23°44′04″S 45°01′35″W). Os caranguejos foram obtidos manualmente, a partir de coletas mensais, por meio de mergulho autonomo, entre janeiro de 2004 e fevereiro de 2007. Um total de 168 caranguejos foi obtido, 64 machos e 104 femeas. Foram executadas regressoes entre a largura da carapaca (LC), variavel independente e o comprimento da carapaca (CC), largura do abdomen (LA) e altura e comprimento do propodo quelar (APQ e CPQ), como variaveis dependentes, aplicando a funcao potencia y = a x b . Os machos jovens apresentaram alometria positiva para o crescimento do gonopodio. Enquanto que para nas femeas jovens foi registrado um padrao alometrico positivo para o crescimento do abdomen. Os padroes de crescimento registrados para M. tortugae estao associados com a estrategia reprodutiva da especie, ou seja, a preparacao das partes do corpo envolvidas com a transferencia de gametas e a incubacao dos ovos, como os gonopodios para os machos e o abdomen para as femeas. De acordo com os resultados obtidos, a maturidade morfologica e atingida em 12,95 mm LC para os machos e em 22,40 mm LC para as femeas. Os padroes gerais demonstrados por M. tortugae seguem o modelo geral descrito para os Brachyura.

Relative growth, sexual maturity, and breeding season of three species of the genus Persephona (Decapoda: Brachyura: Leucosiidae): A comparative study

aria’ dine cristine almeida, ce’lia mary hiyodo, valter jose’ cobo, giovana bertini, vivian fransozo and gustavo monteiro teixeira NEBECC (Crustacean Biology, Ecology and Culture Study Group), Universidade Federal de Uberlândia, Instituto de Biologia, Campus Umuarama, Rua Ceará, s/n, 38400-902, Uberlândia, MG, Brazil, Universidade de Taubaté, Laboratório de Biologia Marinha, Instituto de Biociências, Avenida Tiradentes, 500, 12030-180, Taubaté, SP, Brazil, Universidade Estadual Paulista, Campus Experimental de Registro, Rua Nelson Brihi Badur, 430, 11900-000, Registro, SP, Brazil, Instituto Federal de Educação, Ciência e Tecnologia Baiano, BR 420, Km 2.5, 45320-000, Santa Inês, BA, Brazil, Universidade Estadual de Londrina, Departamento de Biologia Animal e Vegetal, PR 445, Km 380, 86051-990, Londrina, PR, Brazil

Onset of sexual maturity and relative growth of the freshwater crab Trichodactylus fluviatilis (Trichodactyloidea) in south-eastern Brazil

The main purpose of this study was to provide an estimate for the onset of morphological sexual maturity in the freshwater crab Trichodactylus fluviatilis, from a population located in south-eastern Brazil, based on the relative growth relationships, as well as the characterization of “handedness”. Monthly collections were carried out at night, from January 2006 to January 2007, in a small water body. In the laboratory, the crabs were sexed; the following body structures were measured and the estimate of onset of sexual maturity was given by the logistic function, as y = a/(1 + be − cx ), for 50% of the population to reach the adult phase (CW50carapace width). Right propodus length and abdomen width were the best-fit relationships to represent the onset of sexual maturity for males and females, respectively. Based on the logistic function, the onset of sexual maturity was estimated to occur at around 18 mm CW for both sexes. The relative growth recorded for this species is consistent with the model for brachyuran crabs (Hartnoll RG. 1982, Growth. In: Bliss, DE, editor. The biology of Crustacea: embryology, morphology and genetics. New York: Academic Press. p. 111–196), except for the abdomen growth, which is likely to be an adaptive condition related to protection of the newly hatched young.

BRACHYURAN CRABS (DECAPODA, BRACHYURA) ASSOCIATED WITH THE GREEN SPONGE AMPHIMEDON VIRIDIS (DEMOSPONGIAE) FROM ITAGUA BEACH, SOUTH-EASTERN COAST of BRAZIL

Univ Estadual Paulista, UNESP, Inst Biociencias Botucatu, Postgrad Course Zool, BR-18618970 Botucatu, SP, Brazil

Comparison of the population biology of Epialtus bituberculatus from two rocky shores with distinct hydrodynamic patterns

Departamento de Zoologia Instituto de Biociencias Universidade Estadual Paulista-UNESP, Distrito de Rubiao Junior, s/n, CEP: 18618-970, Botucatu, Sao Paulo

The population structure of two sympatric hermit-crab species on a subtidal rocky shore of an island in southeastern Brazil

The main goal of this investigation was to characterize the population structure and shell occupancy of two sympatric hermit-crab species, Pagurus brevidactylus and Paguristes tortugae. The study was undertaken at Couves Island on the southeastern coast of Brazil, from March 2010 through February 2011, on subtidal rocky bottoms. Specimens were collected by SCUBA diving sessions. A total of 195 individuals of P. brevidactylus and 132 of P. tortugae were examined. Both populations showed unimodal size-frequency distributions, which were non-normal for P. brevidactylus and normal for P. tortugae. The median size of P. brevidactylus was significantly smaller than P. tortugae; in both species, males were significantly larger than females. For both, juveniles and ovigerous females were recorded in all size classes and in almost the entire sampling period. No significant departures from the 1:1 sex ratio were detected, although some size classes were skewed. Overlaps in shell occupation were recorded. Pagurus brevidactylus and P. tortugae showed similar population features; they reached sexual maturity at small sizes, and the nearly year-round presence of young and ovigerous females suggests continuous reproduction. These inter-specific interactions involving resource partitioning suggest a regulatory process that is probably part of the equilibrium strategy of these populations.

First zoeal stage of ? Cataleptodius parvulus (Fabricius, 1793) and Xanthodius denticulatus (White, 1848) (Decapoda: Brachyura): larval evidences and systematic position

The first zoeal stages of ?Cataleptodius parvulus and Xanthodius denticulatus are described and compared with zoeae of other members of the subfamily Xanthinae. The larvae of ?C. parvulus and X. denticulatus differ mainly in: 1) spinulation of rostral and dorsal spines; 2) type of antenna; 3) setation of the basis of first maxilliped; and 4) type of telson. Features common to both species include a carapace provided with well-developed spines on the dorsal (1), rostral (1), and lateral (2) portions; and the antennal protopod and rostrum similar in length. The morphological differences between the zoea I of X. denticulatus and ?C. parvulus are nevertheless consistent enough to suggest that these species do not belong to the same genus Xanthodius Stimpson, 1859 as previously supposed. Also we presume that ?C. parvulus does not belong to the genus Cataleptodius.

Assessment of reproductive capacity in females of Callinectes danae Smith, 1869 (Brachyura, Portunoidea) during a period of high reproductive activity

The reproductive capacity of the swimming crab Callinectes danae Smith, 1869 was assessed based on the reproductive investment (RI) of ovigerous females and the gonadosomatic index (GI) of non-ovigerous adult females. Crabs were collected in June 2009 with a shrimp fishing boat at Ubatuba (23° 26′S 45° 02′W) São Paulo, Brazil. Overall, 191 adult females were analyzed, of which 108 were ovigerous and 83 non-ovigerous. The size of ovigerous females ranged from 54.5 to 79.8 mm carapace width (CW) and non-ovigerous females ranged from 56.0 to 80.9 mm CW. RI values did not differ among the size classes (ANOVA, p > 0.05), with an overall mean of 15.8%. The same occurred with the Gonadossomatic index for non-ovigerous females, for which the mean value was 11.7%. The regression between the dry weight of the egg mass and the dry weight of the crab (Student’s t, p = 0.25; ttab = 1.66; tcal = 0.66) indicated an isometric relationship for the variables analyzed. The simultaneous occurrence of gonadal maturation and embryonic development in ovigerous females suggests that these crabs may spawn at least twice in the same breeding season and reveals the need for evaluation of the allocation of energy in subsequent spawns.