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Pachygrapsus transversus, P. gracilis, and Geograpsus lividus are intertidal crabs, whose ultrastructure of spermatophores and spermatozoa are unknown. In this work, we characterized the ultrastructure of the spermatophores and spermatozoa of these three species comparing them to the results of previous research on molecular phylogeny of Grapsidae. Fragments of the posterior vas deferens were processed for routine in transmission electron microscopy. Pachygrapsus transversus and G. lividus exhibit coenospermic spermatophores, while Pachygrapsus gracilis presents cleistospermic spermatophores. The spermatozoa of all three species present the typical pattern seen in Thoracotremata. The acrosome is wider than long, with an acrosome length to width ratio of 0.82 ± 0.022 in P. transversus, 0.75 ± 0.008 in P. gracilis, and 0.82 ± 0.024 in G. lividus. The main specific sperm differences were observed in the perforatorial chamber, the operculum and the concentric acrosomal layers. Pachygrapsus transversus has a flaskshaped perforatorial chamber with a prominent narrowing under the apex, while Pachygrapsus gracilis exhibits a flask-shaped perforatorial chamber with a slight narrowing under the apex, thus wider than that of P. transversus. Geograpsus lividus presents a club-shaped perforatorial chamber with a conical apex. The acrosome of P. transversus has a narrow inner layer while the outer layer presents peripheral concentric lamellae near the opercular pole. In P. gracilis, the inner acrosomal layer of the acrosome is shifted toward the apical portion of the spermatozoon and the outer layer exhibits peripheral concentric lamellae throughout its extension. Geograpsus lividus shows a narrow and electron-dense inner layer shifted toward the opercular pole and curved operculum, unlike the pattern found for the Pachygrapsus species. The differences in the morphology of spermatophores suggest different strategies of transfer and/or storage of spermatozoa between the studied species. The spermatozoal ultrastructure supports the phylogenetic proximity of Pachygrapsus species and also demonstrate that spermiotaxonomy is a useful tool to be associated to molecular data.

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infraestrutura utilizada ao longo destes cinco anos de doutorado.Ao meu orientador Prof. Dr. André Carrara Morandini pela amizade, apoio e compreensão ao longo desses dez anos trabalhando aqui no Laboratório. É incontável o tanto que eu aprendi contigo ao longo desses anos. Obrigada por ser um exemplo de profissional e parceria de sempre.Ao Prof. Dr. Fernando José Zara que continua sendo um exemplo de profissional sempre presente me auxiliando nas descobertas acadêmicas. Obrigada Zara e pessoal do Laboratório de Biologia Celular da UNESP de Jaboticabal por me acolherem sempre que eu preciso.Agradeço à Comissão de Pós Graduação, a qual fui representante discente por um ano (Prof.

The box jellyfish Chiropsalmus quadrumanus (Chirodropida: Cubozoa: Cnidaria) is common in warm waters. Although it is assumed that external fertilization is a characteristic of Chirodropida, the life history of C. quadrumanus is not yet known since its reproductive behavior has never been described, nor has the polyp has been found in nature. As a result, in the absence of documentation of reproductive behavior, we sought to test the hypothesis of external fertilization through a histological analysis of the female gonads. Herein, we analyze ten females collected in São Paulo and Rio de Janeiro (Brazil) and describe the gonadal organization and pattern of oocyte development. The discovery of four distinct stages of oocyte differentiation augments the scant existing reports of the structural and functional maturation of sex cells in Cubozoa species. Furthermore, the gonads of mature females comprise both mature (average diameter of 122 µm) and immature oocytes, suggesting that C. quadrumanus is iteroparous and exhibits multiple reproductive cycles during its life. Medusa bell size was not found to correlate with maturity state as even small females possessed a high percentage of oocytes in late vitellogenesis, suggesting that sexual maturation occurs rapidly in C. quadrumanus females.