Error cascade in taxonomy: The case of Cardiomya perrostrata (Mollusca: Bivalvia: Cuspidariidae) in Brazilian waters.

Successions of erroneous taxonomic identifications in biodiversity studies are an undesirable but not rare phenomenon. Such cascades of errors frequently involve taxa with few, polymorphic diagnostic characters, such as representatives of the cuspidariid genus $\textit{Cardiomya}$. Four species of the genus are believed to live in Brazilian waters: $\textit{C. cleryana}$ (d'Orbigny, 1842), $\textit{C. ornatissima}$ (d'Orbigny, 1853), $\textit{C. striata}$ (Jeffreys, 1876) and $\textit{C. perrostrata}$ (Dall, 1881). Many reported occurrences of these species are based on misidentifications, but the error cascade of incorrect records of $\textit{C. perrostrata}$ is by far the most extensive. Although the species has been reported to live in Brazilian waters for about half a century, all previous records seem to be based on a succession of mistaken identifications. This paper redescribes $\textit{C. perrostrata}$ based on an analysis of the type series, several lots of museum vouchers and new material collected in the Campos Basis (Rio de Janeiro, Brazil). Ontogenetic changes in shell outline and ultrastructural details of the hinge plate, periostracal surface and larval shell are described and illustrated for the first time. Based on a critical appraisal of the literature, we present an updated geographic and bathymetric distribution of the species. $\textit{Cardiomya perrostrata}$ displays a gradual increase in the relative length of the rostrum during its ontogeny and in larger specimens the rostrum is more prominently curved upwards. The larval shell is of type 2D, measuring about 215-235 μm in length. The periostracum is minutely pitted and a lithodesma is present. Its distribution is Western Atlantic, ranging from 42°N to 30°S, in depths of 18 to 1646-1829 m. $\textit{Cardiomya knudseni}$ (Allen & Morgan, 1981), a possibly related amphi-Atlantic species whose type material has been lost, is regarded herein as a $\textit{nomen dubium}$.During his participation in this study, the first author was financially supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, BEX: 8339/12-0; and the second author by NSF grant DEB-0918982 to Rüdiger Bieler

A review on macrobenthic trophic relationships along subtropical sandy shores in southernmost Brazil

Main trophic relationships that occur along the exposed sandy shores in southernmost Brazil (,336 S) are established taking into account several biological compartments operating at morphodynamically distinct environments. Beaches are predominantly of the intermediate type but some stretches of coastline are truly dissipative (Cassino Beach) or tending-to-reflective (Concheiros Beach), presenting thus diverse biological compartments and inhabitant macrobenthic assemblages. Dense concentrations of the surf-zone diatom Asterionellopsis glacialis are responsible - at least for the intermediate shorelines - for the most year-round primary production, sustaining several consumers up to tertiary level. Among them, bivalves Amarilladesma mactroides, Donax hanleyanus and the hippid crab Emerita brasiliensis can account for more than 95% of all the surf-zone secondary production, in addition to the elevated biomass of the suspension-feeder polychaete Spio gaucha and the scavenger isopod Excirolana armata. Crabs, whelks, carnivorous polychaetes, seabirds and surf-zone fishes may also be present and occupy superior trophic levels depending on the beach morphodynamics. Based on the high species richness, abundance and the role of macrobenthic fauna in transferring matter and energy to seabirds and the surf-zone fish assemblages, we address this important issue on the Southwestern Atlantic ecology. Conservation efforts should be implemented for the southernmost Brazilian sandy shores, at least for those non urbanized areas.As principais relac¸o˜ es tro´ ficas observadas ao longo da costa arenosa exposta do extremo sul do Brasil (,336 S) sa˜o estabelecidas levando-se em considerac¸a˜o os va´ rios compartimentos biolo´ gicos que operam em ambientes morfodinamicamente distintos. Estas praias sa˜o predominantemente do tipo intermedia´ rio, embora alguns trechos sejam dissipativos (Praia do Cassino) ou apresentem tendeˆncias reflectivas (Praia dos Concheiros), possuindo compartimentos biolo´ gicos diversificados e associac¸o˜es macrobentoˆnicas residentes. Densas concentrac¸o˜ es da diatoma´cea Asterionellopsis glacialis sa˜o responsa´ veis - pelo menos para as praias intermedia´ rias - por grande parte da produtividade prima´ ria anual, sustentando va´ rios consumidores ate´ o nı´vel tercia´ rio. Entre estes, os bivalves Amarilladesma mactroides, Donax hanleyanus e o crusta´ceo Emerita brasiliensis sa˜o responsa´ veis por mais de 95% de toda a produc¸a˜o secunda´ ria da zona de surfe, em adic¸a˜o a` elevada biomassa do poliqueta suspensı´voro Spio gaucha e do iso´pode necro´fago Excirolana armata. Caranguejos, gastro´ podes, poliquetas carnı´voros, aves marinhas e peixes da zona de surfe tambe´m podem estar presentes, ocupando nı´veis tro´ ficos superiores dependendo da morfodinaˆmica praial. Baseado na alta riqueza de espe´cies, na abundaˆncia e no papel da macrofauna bentoˆ nica em transferir mate´ria e energia para as aves marinhas e as assemble´ias de peixes da zona de surfe, esta importante questa˜o ecolo´ gica do Atlaˆntico Sudoeste foi investigada. Esforc¸os de conservac¸a˜o devem ser implementados nas praias arenosas do extremo sul do Brasil, pelo menos naquelas a´ reas na˜o urbanizadas