Estrutura fina do espermatozóide de Tagelus plebeius (Lightfoot) (Mollusca, Bivalvia) do litoral norte do Brasil

Abstract

ABSTRACT. FINE STRUCTURE OF THE SPERMAT07.00N OF TA GF.J.US f'/.F.BF./US (LIGHTFO.OT) (MOLLUSCA, BIVIILVIII) OF THE NORTH LlTTORIIL OF BRII ZIL. It is described lhe sperm ultraestructure differentiation during spenniogenesis 01' Togellls plebeius (Lightloot, 1786). The spennatozoon is an unillagellated cell 01' the primitive type . The head region contains a rounded or conical nucleus sUlTounded by acrosome. Thc middle piece contains four mitochondria which are arranged around the axoneme. The flagellum contains the usual microtubular axoneme. KEY WORDS. Mollusca, Bivalvia, Toge/lIs plebeius, ultrastructure, spermatozoa Quase nada é conhecido sobre a biologia deste bivalve no Brasi I. Esses animais são citados apenas em trabalhos dc si stemática ou em listas de distribuição de espécies de moluscos do litoral brasileiro. A reprodução, o desenvolvimento e o ciclo sexual são pontos de vital importância na pcsquisa de sua biologia, pois sem indicações seguras sobre o ritmo e ciclo reprodutivo outros aspectos biológicos seriam dificilmente compreendidos. Com respeito à maturação espermática de lamelibrânquios, observações ultraestruturais têm sido realizadas e publicadas (LONGO el aI. 1969), e mais recentemente estudos concernentes a espermatogênese (DORANGE & PENNEC 1989; ROCl-lA & AZEVEDO 1990). A morfologia espermática tem sido sucessivamente examinada na filogenia de Marsupiais (HUGHES 1965) e Gastropoda FRANZÉN (1955) e tem sido sugerida uma avaliação correta para conhecimento da ultraestrutura do espermatozóide de bivalves, que possa ser usada na taxonomia proposta (POPHAM 1979 ; FRANZÉN 1983). A estrutura e desenvolvimento do espermatozóide da grande maioria de moluscos bivalves tem sido

Reproductive cycle of Tagelus plebeius (Mollusca: Bivalvia) in the estuary of the Cachoeira River, Ilhéus, Bahia, Brazil

“…Despite the economic interest of T. plebeius, studies on the reproduction of this species are few. In Brazil, Matos et al (1997) described aspects of the structure of the spermatozoa, and Ceuta et al (2010) recorded occasional hermaphroditism in this species. Cledón et al (2004) studied the reproductive cycle of T. plebeius in Argentina.…”

Shell Morphology and Sperm Ultrastructure ofSolen tehuelchusHanley, 1842 (Bivalvia: Solenidae): New Taxonomic Characters

“…They also described the presence of a perforatorium. We were not able to recognize the perforatorium based on the fi gure provided in Matos et al (1997).. Even so, the general uniformity between the spermatozoa of the Solen species and those of the solecurtids may refl ect the close phylogenetic relationships between these two groups.…”

“…Despite this general similarity, there are diagnostic differences, primarily in the architecture of the acrosome. According to Matos et al (1997), acrosomal vesicles of T. plebeius spermatozoa were dome-shaped in sagittal sections. These domes had larger bases in comparison with their tops.…”

“…In Solen, the morphology of the spermatozoa appears to be conserved, although there are important distinctions in the acrosome, in particular in its length, especially when compared with Ensis ensis Linnaeus, 1758 (Pharidae), and the distinct pattern of electron density in the base of the acrosome in S. tehuelchus (Casas and Subirana 1994). The male gametes of the Solen species are generally similar to those of the solecurtid Tagelus plebeius (Lightfoot, 1786), which also has a short acrosome with an electron-dense base and rounded nucleus (Matos et al 1997). Despite this general similarity, there are diagnostic differences, primarily in the architecture of the acrosome.…”