Espermiotaxonomia e análise comparativa do sistema reprodutor de caranguejos aranha (Mithracidae)
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Data
2017-01-19
Autores
Assugeni, Camila de Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os caranguejos aranha pertencentes à superfamília Majoidea possuem grande diversidade de cor, morfologia corpórea e de habitat. A família Mithracidae recentemente foi revisada com base em dados morfológicos e moleculares, sendo assim novos gêneros foram propostos e algumas especiés redistribuídas. O objetivo deste estudo foi descrever a biologia reprodutiva de alguns membros de Mithracidae por meio da ultraestrutura dos espermatozoides e espermatóforos utilizando a microscopia eletrônica de transmissão e varredura, a fim de corroborar hipóteses baseadas em DNA e morfologia existentes para Mithracidae. Assim, os resultados encontrados na espermiotaxonomia mostram que esta é uma ferramenta eficiente para o estabelecimento de relações filogenéticas uma vez que, a morfologia dos espermatozoides, com base no padrão encontrado em Brachyura, permitiu a divisão das espécies entre os gêneros e, desta maneira, corroborou a filogenia molecular mais recente para a família. A histologia do sistema reprodutor masculino e dos receptáculos seminais (RS) de algumas espécies dos gêneros Mithrax, Mithraculus, Damithrax e Omalacantha foi realizada para verificar mecanismos de transferência espermática. A histologia dos receptáculos seminais mostrou que as fêmeas não são formadoras de pacotes espermáticos, já que todo material genético encontra-se misturado no interior do RS, sendo assim impossível identificar se a fêmea copula com mais de um macho. Caso isto ocorra, o esperma é utilizado de maneira aleatória durante o processo de fertilização, quando o órgão de estocagem torna-se uma ampla câmara de fertilização. As secreções produzidas pelo epitélio dorsal do receptáculo seminal são reativas para proteínas e polissacarídeos neutros, entretanto, ao redor das massas espermáticas foi encontrada uma secreção reativa para polissacarídeos ácidos. Assim, propõe-se que a secreção ao redor dos espermatozoides no RS com reação positiva para polissacarídeos ácidos é proveniente do fluido seminal dos machos com provável função antibacteriana. A histologia do sistema reprodutor masculino mostrou uma morfologia simplificada com ausência de glândulas acessórias. Sendo assim, em espécies com esta característica pode-se prever que este padrão reflita na ausência de pacotes espermáticos ao menos em Majoidea.
Spider crabs belonging to the superfamily Majoidea possess great diversity of color, body morphology and habitat. The family Mithracidae has recently been revised based on morphological and molecular data, thus new genera have been proposed and some species redistributed. The objective of this study was to describe the reproductive biology of some members of Mithracidae by means of the ultrastructure of spermatozoa and spermatophores using transmission and scanning electron microscopy in order to corroborate the hypotheses based on DNA and morphology existing for Mithracidae. Thus, the results found in spermiotaxonomy show that this is an efficient tool for the establishment of phylogenetic relationships based on the morphology of the spermatozoa, following the pattern found in Brachyura, allowed the division of the species between the genera and, in this way, corroborated the most recent molecular phylogeny for the family. The histology of the male reproductive system and the seminal receptacles (RS) of some species of the genera Mithrax, Mithraculus, Damithrax and Omalacantha were performed to verify mechanisms of sperm transfer. The histology of the seminal receptacles showed that females are not spermpacket forming, since all genetic material is mixed within the RS, thus it is impossible to identify if the female copulates with more than one male. If this occurs, the sperm is used at random during the fertilization process, when the storage organ becomes a large fertilization chamber. The secretions produced by the dorsal epithelium of the seminal receptacle are reactive for proteins and neutral polysaccharides, however, around the sperm masses a reactive secretion was found for acidic polysaccharides. Thus, it is proposed that the secretion around the spermatozoa in RS with positive reaction for acid polysaccharides comes from the seminal fluid of males with probable antibacterial function.The histology of the male reproductive system showed a simplified morphology with absence of accessory glands. Thus, in species with this characteristic it can be foreseen that this pattern reflects in the absence of spermatic packages at least in Majoidea.
Spider crabs belonging to the superfamily Majoidea possess great diversity of color, body morphology and habitat. The family Mithracidae has recently been revised based on morphological and molecular data, thus new genera have been proposed and some species redistributed. The objective of this study was to describe the reproductive biology of some members of Mithracidae by means of the ultrastructure of spermatozoa and spermatophores using transmission and scanning electron microscopy in order to corroborate the hypotheses based on DNA and morphology existing for Mithracidae. Thus, the results found in spermiotaxonomy show that this is an efficient tool for the establishment of phylogenetic relationships based on the morphology of the spermatozoa, following the pattern found in Brachyura, allowed the division of the species between the genera and, in this way, corroborated the most recent molecular phylogeny for the family. The histology of the male reproductive system and the seminal receptacles (RS) of some species of the genera Mithrax, Mithraculus, Damithrax and Omalacantha were performed to verify mechanisms of sperm transfer. The histology of the seminal receptacles showed that females are not spermpacket forming, since all genetic material is mixed within the RS, thus it is impossible to identify if the female copulates with more than one male. If this occurs, the sperm is used at random during the fertilization process, when the storage organ becomes a large fertilization chamber. The secretions produced by the dorsal epithelium of the seminal receptacle are reactive for proteins and neutral polysaccharides, however, around the sperm masses a reactive secretion was found for acidic polysaccharides. Thus, it is proposed that the secretion around the spermatozoa in RS with positive reaction for acid polysaccharides comes from the seminal fluid of males with probable antibacterial function.The histology of the male reproductive system showed a simplified morphology with absence of accessory glands. Thus, in species with this characteristic it can be foreseen that this pattern reflects in the absence of spermatic packages at least in Majoidea.
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Palavras-chave
Caranguejo aranha, Majoidea, Espermatozoide, Receptáculo seminal