Reproduction, growth and longevity of Aegla marginata sampled with traps in Intervales State Park (Brazil) from October 2013 to December 2014 are described. Male and female carapace lengths (CL) ranged in size from 5.50 to 20.00 mm and 5.20 to 19.67 mm, respectively. Functional sexual maturity was determined at a CL of 9.28 mm. The main reproductive period occurred during colder seasons (autumn and winter, March–August). Egg number varied between 40 and 146 (mean ± SD; 95 ± 31.5), with an average reproductive output of 10.8% of the female weight, a value close to that found in other anomurans, enough to guarantee the success of this species during embryonic development. Fecundity increased with animal size (ANCOVA, p < 0.05), which allows an animal to produce more eggs, maximising reproductive efficiency, according to its size. Sex ratio was skewed towards males (Chi-Square, p < 0.05), especially during the reproductive period, in which females tended to exhibit cryptic behaviour when incubating eggs. The number of females and males was similar in the months before reproduction, suggesting that females were more active looking for food to store energy for the next reproductive period, and/or were looking for mates. The longevities of 2.43 (males) and 2.49 (females) years (Von Bertalanffy method) corroborate other studies that estimated a longevity of 2 to 3.3 years for Aegla spp. We conclude that A. marginata has seasonal reproduction and recruitment. All the information gathered here should be useful to future studies with other populations of A. marginata outside protected areas.

Guanabara Bay, located at Rio de Janeiro, Brazil, is a highly urbanized and polluted estuary that houses different port areas, shipyards, and marinas of intense maritime traffic. This infrastructure is widely associated with the introduction and spread of non-native sessile species. A rapid assessment of non-native benthic sessile species conducted in the bay in late 2022 across 19 sites identified a total of 83 taxa, both native and non-native, classified into the following main groups: one Cyanophyta, 13 Macroalgae, 14 Porifera, 11 Cnidaria, six Bryozoa, five Annelida, 10 Mollusca, six Crustacea, 10 Echinodermata, and seven Ascidiacea. Our findings revealed the proliferation of the Asian green mussel (Perna viridis Linnaeus, 1758), a species noted for its exceptional ability to achieve extremely high biomass levels globally. In Brazil, the bivalve was first reported less than 6 years ago in 2018 at Guanabara Bay, on a mariculture farm at Arraial do Cabo (200 km away) in 2023 and more recently in the south (Paranaguá Bay), besides two coastal islands outside Guanabara Bay on natural rocky shores. The present survey recorded P. viridis at 17 sites, including natural substrata, co-occurring with native species. No Tubastraea spp. were observed in Guanabara Bay. Controlling and mitigating the consequences of bioinvasion events can be challenging, but biosafety protocols should be adopted in the near feature to minimize the risks and impacts caused by species dispersal.

Hermit crabs are soft-abdomen decapod. They depend upon gastropod shells for protection, with the latter influencing growth rate, mortality and reproduction. The present work aims to provide the information about the biology and reproduction of Pagurus brevidactylus in a preservation area in Brazilian southeastern littoral. The material was sampled through active searching by SCUBA diving and refuge traps. We analyzed population structure, fecundity, reproductive output (RO), reproductive periodicity and shell utilization for P. brevidactylus. In total, 54 males, 18 non-ovigerous females, 34 ovigerous females and 10 juveniles were sampled. The females had a fecundity of 69.5 ± 65 eggs, which was lower than that compared to other populations from different localities. The RO ranged from 1.48% to 63.04%, with the mean of 26.75 ± 18.23%. There was a positive relationship between egg number and female size. The animals had continuous reproduction, but they reached smaller maximum sizes when compared with other populations. The shell occupation pattern was also different from other localities, the shells of Phrontis alba being the most occupied; this shell has a smaller size when compared to others that P. brevidactylus occupies in other localities. Therefore, P. alba could have had limited the growth and reproduction of P. brevidactylus.

This study analyzes ontogenetic allometry in Aegla marginata Bond-Buckup & Buckup, 1994, a freshwater crustacean, in order to evaluate the growth pattern and the presence of sexual dimorphism, using a multivariate approach. The specimens were sampled from streams in Intervales State Park, São Paulo State, Brazil. For each specimen, we measured the following structures: carapace length and width, chelae height and length, and abdomen length. Allometry was evaluated using Jolicoeur’s multivariate allometric coefficient. Our results showed that for females, ABL (abdomen length) and LCH (left chelae heigh) presented positive allometry; LCL (left chelae length) and RCH (right chelae heigh) isometry; and CL (carapace length), CW (carapace width), and RCL (right chelae length) negative allometry. For males, RCH, LCH, and LCL presented positive allometry; RCL (right chelae length) isometry; and CL, CW, and ABL negative allometry. In addition, sexual dimorphism was amplified with body size.

A new species of Aegla is described and illustrated from Alto Paranapanema (São Paulo State), a sub-basin of the Paranapanema watershed. The new species is compared to all seven species of Aegla currently known from the Paranapanema watershed using both morphological and mitochondrial genetic (COI) characters. Molecular sequence comparison analysis also suggested that several records from the Paranapanema watershed previously attributed to Aegla castro actually belong to different species. Opportunity is taken to provide a photograph of the holotype of A. castro (type locality Iapó River, State of Paraná, Tibagi sub-basin, Paranapanema watershed).