Anatomia de Okenia zoobotryon (Gastropoda: Nudibranchia) procedente de São Sebastião, SP, Brasil

CAPES

Sperm ultrastructure of the Actinocyclidae (Mollusca, Nudibranchia) and homology of the terminal region of nudibranch sperm

Sperm ultrastructure is examined and described for the actinocyclidid nudibranchs Actinocyclus verrucosus, Hallaxa iju and Hallaxa indecora. Although general characteristics were consistent with previously described heterobranch observations, present investigations revealed ultrastructural synapomorphies for the family based on the morphology of the terminal region of the spermatozoon. In actinocyclidids, the axonemal microtubules penetrate for some distance beyond the annulus, and the annular accessory body elongates to completely seal the terminal region. Chromodoris also has an annular accessory body that completely seals the axoneme and terminal region, but it does not extend far beyond the annulus, and it is possible that these states were derived independently. Cytochemical staining confirmed that there was no glycogen present in the posterior region of the sperm for H. indecora or Chromodoris kuniei. However, representatives of other chromodoridid genera (Noumea, Risbecia) have an axoneme that penetrates through the entire annular complex, after which it is sheathed by a glycogen deposit. Similarities in the acrosomal complex support the proposed sister group relationship between the Actinocyclidae and Chromodorididae.

Basal chromodorid sperm ultrastructure (Nudibranchia, Gastropoda, Mollusca)

The relationship between three genera considered basal in the Chromodorididae (Cadlina, Tyrinna, Cadlinella) has not yet been resolved by traditional morphological means. Here we examined the sperm ultrastructure of Tyrinna nobilis, Tyrinna evelinae, Cadlina flavomaculata and Cadlina cf. nigrobranchiata, with the expectation of finding phylogenetically informative characters. No Tyrinna or Cadlina species showed sperm similarities to Cadlinella. Both Cadlina species and Tyrinna nobilis (but not T. evelinae) exhibited coarse striations in the acrosomal pedestal. The putative fibers that occurred between the coarse striations of the pedestal are condensed into a layer in Cadlina and Tyrinna, but not in other species that also have coarse striations (Gymnodoris), and may constitute evidence for a close relationship. Tyrinna evelinae possessed fine acrosomal striations, which was shared with other Chromodorididae, Actinocyclidae and the cryptobranchs Rostanga and Aphelodoris. We also examined the sperm ultrastructure of 'Chromodoris' ambiguus, an animal which has shown molecular affinities to species of Cadlina, and not Chromodoris. The sperm of 'C'.' ambiguus did not exhibit the typical Cadlina characteristics, but also showed important differences to other investigated Chromodoris species.

Is Cadinella ornatissima a chomodorid? Sperm ultra structure in an enigmatic nudibranch (Opisthobranchia Mollusca)

Sperm ultrastructure is described for the nudibranch gastropod Cadlinella ornatissima, type species of the genus Cadlinella (Thiele). Although C. ornatissima exhibits most of the sperm features characteristic of other Opisthobranchia and the Pulmonata (a small, rounded acrosomal vesicle, a complex, helical, mitochondrial derivative - partially paracrystalline, coarse fibres associated with the axoneme), it also possesses a number of previously undescribed and possibly unique features (a longitudinally inrolled acrosomal pedestal, an axial structure within the cavity of the acrosomal pedestal, an electron-dense collar at the anterior region of the acrosomal pedestal, the presence of crystalloid bodies within the glycogen helices of the mitochondrial derivative). To our knowledge this is the first report of crystalloid bodies in mature sperm of any mollusc. Collectively this evidence raises questions concerning the affinities and systematic position of Cadlinella within the Nudibranchia. The peculiar nature of the sperm differences, in comparison with other investigated nudibranchs, suggest that Cadlinella is not easily linked to either the Cadlinidae or Chromodorididae, and should be considered incertae sedis.

Lista actualizada de los opistobranquios (Mollusca: Gastropoda: Opisthobranchia) de las costas catalanas

Se presenta una lista taxonómica de las especies de opistobranquios (Mollusca: Gastropoda: Opisthobranchia) registradas hasta el presente en aguas litorales o de profundidad de las costas catalanas (NE Península Ibérica). Esta lista se basa en citas publicadas en la literatura, en citas fotográficas procedentes de Internet, en comunicaciones personales de buceadores y en numerosos datos inéditos de recolecciones del autor. De cada especie se indican las referencias bibliográficas, y en el caso de los datos no publicados o procedentes de Internet, se indican las localidades concretas donde se han recolectado u observado. En aguas catalanas se registran hasta el momento un total de 205 especies de opistobranquios: 36 de Cephalaspidea s.s., 9 de Architectibranchia, 7 de Anaspidea, 11 de Thecosomata, 3 de Gymnosomata, 14 de Sacoglossa, 2 de Umbraculacea, 8 de Pleurobranchacea y 115 de Nudibranchia (55 Doridina, 14 Dendronotina, 4 Arminina y 42 Aeolidina). De estas especies, tres de ellas se citan por vez primera para el litoral ibérico (Runcina adriatica, R. brenkoae y Tritonia lineata), mientras que otras siete más no habían sido recolectadas en el litoral catalán (Runcina coronata, R. ferruginea, Elysia translucens, Ercolania coerulea, Berthellina edwarsi, Doris ocelligera y Piseinotecus gabinieri). Teniendo en cuenta la extensión del litoral catalán (550 km de costa) y comparando con los datos publicados para otras regiones costeras de la Península Ibérica, se puede concluir que las costas catalanas son muy ricas en biodiversidad de opistobranquios, y que el grado de conocimiento alcanzado sobre este grupo de moluscos es muy alto.