Morphology of juvenile phase of Achelous spinimanus (Latreille, 1819) (Crustacea, Decapoda, Portunidae) reared in laboratory

Abstract

The swimming crabAchelous spinimanusis an important fishery component of several countries in the Western Atlantic; therefore, knowledge of the different phases of its life cycle is essential for good management of this resource. The juvenile development ofA. spinimanuswas investigated in the laboratory, from megalopae captured in neuston samples at Ubatuba, São Paulo, Brazil (23°26′S 46°09′W), during the summer months of 2005–2007. Rearing was performed in a constant temperature (25 ± 1°C), filtered seawater from the collection location (35 psu) and natural photoperiod. We obtained nine stages of the juvenile phase. All the morphological characters that allow the recognition of the first juvenile stage were drawn and described, as well as the main alterations that occur in the following stages. The sexual differentiation based on the number of pleopods becomes apparent from the third stage on. Some important characters in the identification of the species at the juvenile phase are the number of segments on the exopod of antennule, on the antennal flagellum and on the palp of mandible, beyond the absence of pleopods (even rudimentary) in the first stage.

Morphometric and gonad maturity of the spider crabLibinia ferreiraeBrito Capello, 1871 (Decapoda: Majoidea: Epialtidae) on the south-eastern Brazilian coast

“…Individuals of both sexes were assessed by abdomen adherence to the thoracic sternite. Individuals considered here as immature presented a sealed abdomen, with cementing substances present in the contour of the abdomen (which do not allow its extension) (Bolla & Negreiros-Fransozo, 2015). Individuals showing an unlocked abdomen were considered here as adults, wherein the abdomen could be easily flexed even with the presence of a press-button mechanism, but without cementing substances.…”

Reproductive features of the invasive crab Libinia dubia H. Milne Edwards, 1834 from the Central Mediterranean Sea

“…Individuals were classified as juveniles or adults based on their secondary sexual characteristics. In both sexes, juveniles presented a sealed abdomen, whereas adults presented an unlocked flexed abdomen (Guinot & Bouchard, 1998;Bolla Jùnior & Negreiros-Fransozo, 2015). Furthermore, juvenile females had flat abdomens, whereas adults had domed abdomens.…”