Esli Emanoel Domingues Mosna

In Brachyura, reproduction involves a range of behavioral, morphological, and physiological mechanisms that contribute to reproductive success. The land crab Johngarthia lagostoma , endemic to four oceanic islands in the South Atlantic, shows no clear pre- or post-copulatory guarding behavior, and the mechanisms involved in sexual selection remain uncertain. This study investigated the ontogenetic development of the first gonopod using relative growth analyses and high-resolution imaging techniques, with special emphasis on the corneous unguis, a distal non-calcified structure of unknown function. Morphometric analyses were performed using carapace width as the independent variable and measurements from different gonopod regions, including the corneous unguis, as dependent variables. Relative growth was evaluated using power function, and growth shifts were estimated from the intersection between juvenile and adult growth phases. Nano-computed tomography and X-ray analyses were used to describe the overall morphology of the gonopod and provided detailed visualization of its distal region, including the horny claw and associated setae field. Most biometric relationships showed growth shifts at similar sizes (50–55 mm CW ). In contrast, the corneous unguis showed a delayed ontogenetic transition (64.9 mm CW ), indicating a developmental trajectory distinct from that of the other gonopod regions. The coordinated maturation of most gonopod regions, together with the delayed development of the corneous unguis, indicates differential developmental timing among components of the copulatory apparatus. Although the functional role of the corneous unguis remains uncertain, its distinct ontogenetic pattern supports the hypothesis that it may be involved in post-copulatory reproductive processes associated with sperm transfer and/or ejaculate processing.

The Atlantic Forest is one of the top five biodiversity hotspots on the planet and is considered a global priority for conservation, largely due to extensive human‐driven deforestation. Temporary pools in the Atlantic Forest harbour unique and vulnerable fish assemblages, yet remain poorly studied, particularly within protected areas. In this study, we assessed fish diversity, composition and environmental drivers in 34 temporary pools sampled across dry and wet hydrological periods in the Serra do Mar State Park, southeastern Brazil. A total of 574 individuals representing eight species were recorded, indicating low regional richness, with estimates not exceeding 10 species. Fish abundance, richness, effective number of species, Margalef's K and species composition did not differ between periods. Habitat availability and isolation influenced fish abundance only during the dry period, reflecting contrasting ecological strategies of dominant species. In the wet period, the assemblage structure showed no association with environmental predictors, suggesting a stronger influence of stochastic processes driven by unpredictable flood dynamics. Shrimp abundance had no detectable effect on fish assemblage metrics. Our results indicate that temporary pools are shaped by a combination of historical environmental filtering acting on the regional species pool and contemporary stochastic processes. These findings highlight the ecological dynamics of temporary aquatic habitats, often overlooked in conservation planning, and also reinforce the role of protected Atlantic Forest areas as microclimatic refugia in a rapidly changing world.

Protected estuaries provide reference conditions for assessing coastal biodiversity, but information on swimming crab assemblages in such systems remains limited. This study evaluated the composition, dominance structure, diversity, body size, and spatio-seasonal variation in Callinectes swimming crab assemblages in the Una do Prelado River estuary, within the Barra do Una Sustainable Development Reserve, south-eastern Brazil. Seasonal sampling was conducted at four sites along the estuarine gradient using baited traps. Species composition, abundance, diversity indices and multivariate patterns were analyzed in relation to site and climatic season. A total of 146 individuals from four species were recorded: Callinectes exasperatus, C. danae, C. sapidus and C. bocourti. The assemblage was strongly dominated by C. exasperatus, which represented 81.5% of the total catch. Species richness was low, consistent with the restricted taxonomic scope and environmental filtering expected in estuaries. Abundance varied more clearly than species composition, with higher catches in autumn and at the intermediate estuarine site. Diversity indices indicated low evenness where C. exasperatus was dominant, whereas multivariate analyses detected no significant compositional differences among sites or seasons. As the first study conducted in this protected estuary, our findings provide a baseline for future monitoring of this system. Given the spatial and temporal scope of the study, these results should not be generalized to other protected estuarine systems.

Mangrove forests provide essential ecosystem services in tropical and subtropical coastlines, including shoreline protection against erosion and storms, regulation of water quality, carbon storage,...

This study describes the reproductive systems of male and female Johngarthia lagostoma , a land crab endemic to South Atlantic oceanic islands, focusing on spermatozoa production and storage. Specimens from Trindade Island (Brazil) were analysed for anatomy, histology, and histochemistry. The male system includes a pair of tubular testes showing different stages of spermatogenesis and spermiogenesis, leading to mature spermatozoa. These move to the anterior vas deferens (AVD), which has proximal and distal portions, the latter containing coenospermic spermatophores surrounded by secretion type I, reactive to proteins and acidic and neutral polysaccharides. The median (MVD) and posterior (PVD) vas deferens produce type II (strongly protein-reactive) and type III (weakly protein-reactive) secretions. Accessory glands between the MVD and PVD produce the same secretions plus a secretion type IV, reactive to neutral polysaccharides. These mix with the spermatophores and other vas deferens secretions, increasing the PVD’s secretion volume, crucial for the initial release of spermatophores into the seminal receptacle. The female reproductive system features voluminous seminal receptacles connected to the ovary, comprising mesodermal and ectodermal regions classified as ventral-type connection. Plugs and sperm packets are absent, with the seminal receptacles filled with free spermatozoa, suggesting dehiscence occurs shortly after sperm transfer. The influence of male and female secretions on this process is suggested, alongside their roles in sperm maintenance and fertilization facilitation.

An analysis of reproductive potential can elucidate significant aspects of the population biology and evolution of brachyuran crabs, providing a crucial baseline for conservation efforts concerning endangered species. Johngarthia lagostoma is an endemic species to Atlantic Oceanic islands (Rocas Atoll, Fernando de Noronha, Ascension, and Trindade), and it is classified as endangered (EN) in Brazilian territory according to IUCN criteria. Until now, the reproductive potential of this species has only been described for the Ascension Island population. Therefore, we assessed the reproductive effort and fecundity of J. lagostoma on Trindade Island. A total of 43 ovigerous females in the final stage of embryonic development were analyzed. Their egg masses were removed, weighed, and counted using a volumetric method. The carapace width ranged from 55.3 to 100.1 mm (mean ± standard deviation: 75.2 ± 13.1 mm). It exhibited a good fit and positive correlation with the egg weight and fecundity data but a poor fit and negative correlation with reproductive effort. The contrasting results of fecundity (82,938 ± 43,673 eggs) and reproductive effort (10.5 ± 1.5 %) recorded for J. lagostoma reveal a well-established population on Trindade Island compared to Ascension Island. These observations provide valuable information for proposing more effective management strategies for this endangered species across these Atlantic oceanic islands.