Sistema nervioso y receptores en la cholga, Aulacomya atra atra (Bivalvia: Mytilidae)

Se estudió la anatomía e histología del sistema nervioso del mitílido, Aulacomya atra atra (Molina 1782) (Mytilidae), con énfasis en sus órganos receptores. La anatomía del sistema nervioso de A. atra atra es en líneas generales, similar a la descripta por diferentes autores para el género Mytilus. La diferencia más importante consiste en la ausencia, en A. atra atra, de un tronco común para los conectivos cerebro-viscerales y cerebro-pedales de cada lado. Los ojos branquiales, estatocripto, "osfradio" y "órgano sensorial abdominal" en Aulacomya son asimismo, en sus características más importantes, semejantes a los descriptos para el género Mytilus. Se ha observado en la cholga un "órgano sensorial paleal" par ubicado en la cámara suprabranquial de la cavidad paleal, asociado al eje branquial y que va desde aproximadamente la base del pie hasta el ano sobre el músculo aductor posterior; este órgano no ha sido descripto para Mytilus. Los órganos sensoriales de la cámara suprabranquial de la cholga son semejantes a los descriptos para otras familias de bivalvos; su parecido en morfología y ubicación sugiere que estos órganos pueden cumplir funciones equivalentes

Molecular and morphological analyses reveal new taxa additions to the tribe Streblocladieae (Rhodomelaceae, Rhodophyta)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168374/1/jpy13144_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168374/2/jpy13144.pd

Meridionella gen. nov., a New Genus of Cystocloniaceae (Gigartinales, Rhodophyta) from the Southern Hemisphere, Including M. obtusangula comb. nov. and M. antarctica sp. nov.

The classification of Cystoclonium obtusangulum has been questioned since the species was first described by Hooker and Harvey as Gracilaria? obtusangula. The objective of this study was to provide the first comprehensive taxonomic analysis of Cystoclonium obtusangulum, based on DNA sequences coupled with morphological observations made on syntype specimens and new collections. Sequence divergences of rbcL, UPA, and COI-5P, and maximum-likelihood phylogenies for rbcL and 18S demonstrated that specimens identified as Cystoclonium obtusangulum represent a clade of two distinct species that are distantly related to the generitype Cystoclonium purpureum. A new genus, Meridionella gen. nov., is proposed for this clade. The two species placed in this new genus were morphologically indistinguishable cryptic species, but have disjunct distributions, with Meridionella obtusangula comb. nov. found from temperate to cold coasts of South America and the Falkland Islands and Meridionella antarctica sp. nov., occurring in Antarctic waters. Vegetative and reproductive characters of Meridionella gen. nov. are described, and implications of our results for the biogeography of the family Cystocloniaceae are discussed.Postprint2,23

Intertidal mussel beds from the South-western Atlantic show simple structure and uniform appearance: does environmental harshness explain the community?

Communities of the rocky mid-intertidal zone of the South-western Atlantic are uniform in appearance, dominated by dense monocultures of small-size mussels (Brachidontes rodriguezii and Perumytilus purpuratus). To explain this, two hypotheses have been advanced in the literature: environmental harshness due to high potential evaporation and historical contingency after the Last Glacial Maximum. In this study of Uruguayan and Argentine shores, we address the implications and predictions of these two hypotheses from a biogeographic perspective by studying the regional distribution and composition of mid-intertidal mussels. We conducted an extensive latitudinal sampling survey (21 locations, 34–54°S), along with a compilation of available information on mussel bed composition and mussel predators present along the coastline. Then we constructed latitudinal profiles of ecologically significant environmental variables with specific emphasis on potential evaporation, a proxy for desiccation stress. The results show that mussel beds are composed of two species of small mussels, which coexist over a biogeographic transition zone (40–42°S) related to sea surface water temperature. The distribution of mussels along the coastline studied is not consistent with the environmental harshness hypothesis. In addition, in the Central Patagonian zone (44–50°S), two invertebrate predators also inhabit the intertidal rocky shores. However, these localities showed higher environmental harshness (potential evaporation rate) than non-Patagonian localities. We suggest that further attention should be given to historical contingency in order to advance towards a hypothesis consistent with current knowledge on the post-glacial biogeographic history of the South-western Atlantic.Fil: Adami, Mariana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Zoología Invertebrados; ArgentinaFil: Schwindt, Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Tablado, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Calcagno, Javier Ángel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Labraga, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Orensanz, Jose Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin