Abstract Atya gabonensis Giebel, 1875 and Atya scabra (Leach, 1816) are amphidromous shrimps. In some areas, these species populations are vulnerable due to the anthropogenic impact on their habitats and commercial exploitation. However, basic morphometric data is still lacking. This study provides morphometric data on both species in the Fluvial Island Domain of Paraíba do Sul River basin, Brazil. Sampling was performed bimonthly from January 2013 to March 2014. Individuals were analysed according to sex, weight, carapace length and width, abdomen length, second abdominal pleura height and width, length of third pereopod articles, and length and width of the male appendix interna. We sampled 42 individuals of A. gabonensis and 16 individuals of A. scabra. In both species, females showed abdomen and second abdominal pleura larger than males, while males showed third pereopod articles larger than females, both related to sexual dimorphism. We detected differences in the carapace length × carapace width relationship and in the growth pattern of the male appendix interna between species, with A. gabonensis presenting the carapace and the male appendix interna wider than A. scabra. Morphometric aspects of both species are unpublished for this region, and this data is valuable for A. gabonensis in the western Atlantic and for A. scabra from Rio de Janeiro state. Such information is essential for future systematic assessment and establishment of conservation management policies.

ResumoDecápodes desenvolveram uma ampla variedade de estratégias reprodutivas. Neste estudo foram investigadas características reprodutivas da espécie de PalaemonidaeLeander paulensis. Os indivíduos foram coletados na região costeira de Ubatuba, São Paulo, Brasil. Foram examinadas 46 fêmeas ovígeras quanto aos seguintes aspectos reprodutivos: fecundidade, investimento reprodutivo, perda de ovos e volume dos ovos. Leander paulensis produz uma grande quantidade de pequenos ovos, com fecundidade média de 635 ± 246 ovos. O volume dos ovos aumentou significativamente quando comparado o estágio inicial (0.034 ± 0.008 mm3) com o estágio final de desenvolvimento (0.05 ± correlação com o tamanho das fêmeas. Fêmeas com ovos no estágio 2 apresentaram massa corpórea seca significativamente maior que aquelas carregando ovos no estágio inicial. Esse aumento de massa parece ser decorrente da recuperação de reservas energéticas das fêmeas, que teriam sido utilizadas durante a produção de ovos. Além disso, deve-se considerar neste tipo de avaliação o aumento da massa corpórea em relação ao investimento reprodutivo, assim como da perda de ovos relacionada à massa das fêmeas ou qualquer outra variável dependente do peso.

AbstractDecapod species have evolved with a variety of reproductive strategies. In this study reproductive features of the palaemonid shrimp Leander paulensiswere investigated. Individuals were collected in the coastal region of Ubatuba, São Paulo, Brazil. In all, 46 ovigerous females were examined in terms of the following reproductive traits: fecundity, reproductive output, brood loss and egg volume. Leander paulensis produces a large number of small eggs with an average fecundity of 635 ± 246 eggs. Egg volume increased significantly from early (0.034 ± 0.008 mm3) to late development stage (0.05 ± 0.012 mm3). The reproductive output did not correlate with female size. The weight of females bearing stage 2 eggs was significantly higher than that of females carrying stage 1 eggs. We assume that the reason for this weight gain is the recovery of female reserves that have been depleted for egg production. Moreover, we emphasize that this weight gain must be considered when evaluating weight-dependent variables such as reproductive output or brood loss in relation to female weight. Otherwise, an overestimation of these variables might lead to inaccurate results.

Visando estimar o tamanho em que Callinectes ornatus atinge a maturidade sexual na costa de Ilhéus - BA, exemplares da espécie foram coletados mensalmente entre março de 2003 e fevereiro de 2005. Foi utilizada rede otter-trawl para a obtenção de amostras em três pontos do litoral do município, com duração de 30 minutos cada. Foram coletados 1.221 indivíduos, sendo 918 fêmeas e 303 machos. O tamanho em que 50% dos indivíduos estavam morfologicamente maduros (LC50%) foi de 41,4 mm para as fêmeas e de 44,2 mm para os machos. Houve sincronia ente o tamanho de maturação gonadal e morfológica. O tamanho de maturação encontrado para ambos os sexos foi menor do que os encontrados em outros estudos desenvolvidos na costa brasileira.

Aiming to estimate the onset of the sexual maturity of Callinectes ornatus on the coast of Ilhéus (Bahia, Brazil), we collected multiple specimens of C. ornatus monthly between March 2003 and February 2005. The otter-trawl was used to have population samples of three sites along the coast, lasting 30 minutes each. Analysis was performed from 1,221 individuals (918 females and 303 males). The size at the onset of the morphological maturity was 41.4 mm for females and 44.2 mm for males. There was synchrony between physiological and morphological maturity. The size at the onset of the maturation of both sexes was lower than those found in other studies along the Brazilian coast.