Development of male reproductive system of the blue land crab Cardisoma guanhumi Latreille, 1828 (Decapoda: Gecarcinidae)

Sexual Maturity of an Endemic Insular Land Crab: Priority Information toward the Conservation of Johngarthia lagostoma

AbstractInsular land crabs (Gecarcinidae) can transit between terrestrial and aquatic environments and inhabit vacant ecological niches that other species do not occupy in oceanic islands. During the reproductive period, these crabs migrate between residential and reproductive areas; this is a critical moment because individuals are more vulnerable to stressful conditions, especially species occupying anthropized islands. Currently, many insular crab species are considered threatened; yet few studies have evaluated the biology of this group, especially the size at which individuals reach sexual maturity. Here, we evaluate the size at the onset of morphological, physiological, and functional maturity for the insular land crab Johngarthia lagostoma in Trindade Island (Brazil) and assess the chronology of the events underlying those processes. Males and females exhibited the same order of occurrence of the different maturity processes, starting by being morphologically, physiologically, and, finally, functionally mature at similar sizes (about 56 mm carapace width). This value corresponds to at least half of the maximum size that J. lagostoma reaches in Trindade Island and is close to the average relative value registered to other Gecarcinidae species. Considering the current decline in the population of insular crabs, such estimates can be used in management programs, mainly for the definition and protection of breeding and recruitment areas. Specifically, our results can be used toward the conservation of J. lagostoma, which is currently classified as endangered in Brazil, especially in the isolated population of Trindade Island.

Morphology of the male reproductive system of freshwater prawn Macrobrachium carcinus (Decapoda, Caridea): Functional and comparative aspects

Testes and vasa deferentia are parts of the male reproductive system of decapod crustaceans. Both organs show morphological differences among decapod species in terms of anatomical and histological patterns reflecting the diversity of this group. Describing these features may assist in systematics, phylogenetics, and studies of reproductive behavior, especially for species of commercial interest, such as Macrobrachium carcinus, a native American species that, unusually for this genus, has no precopulation courting behavior. This study aims to describe the reproductive morphology and spermatogenesis of the male freshwater prawn M. carcinus. The male reproductive system of this species consisted of lobed testes connected to the vasa deferentia. The testis of M. carcinus was divided into several lobules. Each lobule was formed by a cluster of germ cells surrounded by connective tissue and nurse cells. This microscopic anatomy and histology of the testicular histoarchitecture has been described for many species of Decapoda and may represent a derived design of the testes. Unlike that in other decapod species, spermatogenesis proceeds in short transitory phases that produce spermatozoa at high concentrations and frequencies, corroborating the uncommon male reproductive behavior of this species. In the spermatic pathway, the lobules develop and fuse before releasing spermatozoa from the testes; however, this process has not been observed in decapods, yet. The neutral compounds secreted by the vas deferens are important for sperm nutrition as females secrete a substance for spermatophore adhesion during reproduction. This study presents different features and dynamics of the spermatogenic process in the male reproductive system of M. carcinus that have not yet been presented in the literature for decapods.

Population biology and color patterns of the blue land crab, Cardisoma guanhumi (Latreille 1828) (Crustacea: Gecarcinidae) in the Northeastern Brazil

The objective of this study was to analyze the population biology and color patterns of Cardisoma guanhumi Latreille, 1828 in a mangrove area in Natal, Rio Grande do Norte, Brazil. Crabs were collected monthly between February 2010 and January 2012 and totaled 1,837 individuals. Sex ratios were similar between males and females in the first year and differed in the second. Sex ratios by size class differed statistically in the extremes of the distribution, with an abundance of males in the large size classes. There was no difference (p > 0.05) in carapace width between males and females in the first year, but in the second year, males were larger than females (p = 0.003), showing the importance of considering interannual variation in such studies. Both sexes presented a unimodal distribution. The size of first maturing of the females was 6.00 cm. Asymptotic carapace width for males was 9.4 cm and females for 9.2 cm, using the Wetherall method. There was no defined modal progression, which made the determination of the Von Bertalanffy growth parameter K impossible. Juveniles were found throughout all months of the year, demonstrating that there was no defined period of recruiting, although slightly fewer juveniles were found in the dry season. Four color patterns were observed, the three first patterns were the same for both sexes, while the fourth pattern was observed in females only. The four color patterns identified could be clearly related to the stage of development (size) and sexual maturity of the animal.