Morfologia comparada dos gonópodos I e II de Mithracidae (Crustacea: Decapoda: Brachyura)
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Data
2017-02-16
Autores
Lianos, Laira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Ao contrário dos outros Decapoda, os caranguejos Brachyura apresentam espermatozoides desprovidos de flagelo. A transferência destas células para a fêmea é realizada com o auxílio do primeiro e segundo par de pleópodos modificados em órgão copulador, os gonópodos. Estas estruturas são fundamentais para a determinação taxonômica dos Brachyura, visto que cada espécie apresenta morfologia singular deste aparato reprodutor. A superfamília Majoidea representa um grande grupo dentro de Brachyura, porém suas relações internas são pouco conhecidas, o que torna a taxonomia de Mithracidae extremamente conturbada. Desta forma, o presente estudo descreve a morfologia dos gonópodos I e II de 12 espécies de Mithracidae, além de Macrocoeloma trispinosum (Latreille, 1825) e confronta os caracteres morfológicos descritos com as recentes hipóteses filogenéticas propostas para o grupo. Para tal, foram utilizadas técnicas em estereomicroscopia e microscopia eletrônica de varredura (MEV). As análises em MEV permitiram identificar regiões estruturais até então desconhecidas e que podem acrescentar informações importantes acerca do funcionamento fisiológico e mecânico da cópula em Majoidea. Além disso, os gonópodos apresentam similaridades morfológicas dentro de cada gênero, sendo que nossos resultados corroboram com as hipóteses filogenéticas propostas com base em caracteres moleculares, salvo algumas exceções. Dentre elas, Damithrax hispidus (Herbst, 1790) e Damithrax caribbaeus (Rathbun, 1920) apresentam diferenças morfológicas nos gonópodos que contrariam a sinonímia proposta para estas duas espécies. Ademais, Pitho laevigata (A. Milne-Edwards, 1875), que foi incluso na família Mithracidae, possui características que diferem significativamente do padrão encontrado para esta família, enquanto Macrocoeloma trispinosum (Latreille, 1825), excluído de Mithracidae, compartilha muitas características com os demais membros desta família.
Unlike other groups of animals, the Brachyuran crabs have spermatozoa without flagelum. Thus, the transfer of these cells for the female is performed with the first and second pair of pleopods modified in copulatory organs, the gonopods. These structures are essential to the taxonomic identification in Brachyura, since each species have an unique morphology of the reproductive apparatus. The superfamily Majoidea represents a large group within Brachyura, however their internal relationship is poorly known, making the taxonomy of Mithracidae extremely difficult. Therefore, the present study describes the morphology of gonopods I and II of 12 species of Mithracidae, besides Macrocoeloma trispinosum (Latreille, 1825) and confronts the morphological characters described here with the most recent phylogenetic hypotheses for the family. We used analytical techniques of estereomicroscopy and scanning electron microscopy (SEM). The SEM analysis identified structural regions unknown until now and can add important information about physiological and mechanical operation of the copulation in Majoidea. In addition, the gonopods share morphological similarities within each genera corroborating with the phylogenetic hypotheses based on molecular characters, except for a few exceptions. Among them, Damithrax hispidus (Herbst, 1790) and Damithrax caribbaeus (Rathbun, 1920) have morphological distinctions in the gonopods that contradict the synonym proposed to both species. Furthermore, Pitho laevigata (A. Milne-Edwards, 1875), included in the Mithracidae, has characteristics that differ significantly from the pattern of the family, while Macrocoeloma trispinosum (Latreille, 1825), recently excluded of the family, shares many characteristics with the other members of the Mithracidae.
Unlike other groups of animals, the Brachyuran crabs have spermatozoa without flagelum. Thus, the transfer of these cells for the female is performed with the first and second pair of pleopods modified in copulatory organs, the gonopods. These structures are essential to the taxonomic identification in Brachyura, since each species have an unique morphology of the reproductive apparatus. The superfamily Majoidea represents a large group within Brachyura, however their internal relationship is poorly known, making the taxonomy of Mithracidae extremely difficult. Therefore, the present study describes the morphology of gonopods I and II of 12 species of Mithracidae, besides Macrocoeloma trispinosum (Latreille, 1825) and confronts the morphological characters described here with the most recent phylogenetic hypotheses for the family. We used analytical techniques of estereomicroscopy and scanning electron microscopy (SEM). The SEM analysis identified structural regions unknown until now and can add important information about physiological and mechanical operation of the copulation in Majoidea. In addition, the gonopods share morphological similarities within each genera corroborating with the phylogenetic hypotheses based on molecular characters, except for a few exceptions. Among them, Damithrax hispidus (Herbst, 1790) and Damithrax caribbaeus (Rathbun, 1920) have morphological distinctions in the gonopods that contradict the synonym proposed to both species. Furthermore, Pitho laevigata (A. Milne-Edwards, 1875), included in the Mithracidae, has characteristics that differ significantly from the pattern of the family, while Macrocoeloma trispinosum (Latreille, 1825), recently excluded of the family, shares many characteristics with the other members of the Mithracidae.
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Palavras-chave
Sistema reprodutor masculino, Microscopia eletrônica de varredura, Taxonomia