| Registro completo |
| Provedor de dados: |
Naturalis
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| País: |
Netherlands
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| Título: |
Reproductive system and spermatozoa ultrastructure support the phylogenetic proximity of Megadasys and Crasiella (Gastrotricha, Macrodasyida)
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| Autores: |
Guidi, L.
Todaro, M.A.
Ferraguti, M.
Balsamo, M.
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| Data: |
2014
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| Ano: |
2014
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| Palavras-chave: |
Cephalodasyidae
Phylogeny
Planodasyidae
Reproductive traits
Spermatogenesis
42.79
42.62
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| Resumo: |
The reproductive system and the spermatozoon of Megadasys sterreri from Lanzarote (Canary Islands, Spain) were studied at structural and ultrastructural levels. The species is a simultaneous hermaphrodite with cross-fertilization and shows paired gonads, the male anterior and the female posterior, and both gametes mature in a caudo-cephalic direction. Sperm ducts converge on the midline and open into a ventral common pore. Two sexual accessory organs are present in the caudal trunk. A pipe-like frontal organ lies between the ovaries and the caudal organ, and is composed of a long, thin region connected to a large zone containing mature and degenerating spermatozoa. The cigar-like caudal organ is elongate, bulky and is made of an anterior glandulo-muscular region and a posterior muscular one. Spermatozoa are long, filiform cells formed by an acrosome, a nucleus-mitochondrial complex, and a flagellum. The long acrosome is composed of an apical twisted region and a basal straight region. The nucleo-mitochondrial complex is formed by a spring-shaped nucleus surrounding basally the mitochondrion and apically a granular material. The flagellum has a 9x2+2 axoneme, characterized by a dense and prominent central sheath surrounding the central tubules. Megadasys sterreri (Cephalodasyidae) shows the same reproductive layout as Crasiella (Planodasyidae): paired gonads, caudo-cephalic maturation of gametes, sperm ducts converging into a common ventral pore, and two sexual accessory organs. Also the spermatozoa ultrastructure shows two similarities in the two genera: a peculiar prominent central sheath in the axoneme and a similar structure of the basal region of the acrosome. Considering the likely polyphyletic nature of the family Cephalodasyidae, and the sister-taxon relationship of Megadasys and Crasiella that emerged from a recent molecular phylogenetic study, a close relationship between the two taxa appears to be very likely; consequently, we propose to remove Megadasys from the family Cephalodasyidae and affiliate it to the family Planodasyidae.
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| Tipo: |
Article / Letter to the editor
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| Identificador: |
http://www.repository.naturalis.nl/record/471589
http://www.repository.naturalis.nl/document/521071
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| Formato: |
application/pdf
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| Fonte: |
Contributions to Zoology (1383-4517) vol.83 (2014) nr.2 p.119
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| Direitos: |
(c) Naturalis
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