Caudofoveata (Mollusca, Aplacophora) from the Western Atlantic: taxonomy and distribution

The Caudofoveata (Aplacophora) can be characterized by having an elongated body covered by spicules (sclerites), abscence of a foot and by the presence of an oral disc in the anterior region. They are commonly found in great oceanic depths and, in some regions, can be ecologically dominant and important in the benthic community structure. On the other hand, as it happens with other deep-sea molluscs, the Caudofoveata are still little known regarding their diversity, taxonomy, and biogeography, especially for the Western Atlantic Ocean. With the aim to contribute to fill this gap, an extensive survey of material of Caudofoveata from the Western Atlantic, including type material, was performed. The species were analyzed in detail, through light microscopy, by birefringence and the scanning eletron microscopy, aiming to observe mainly details of sclerites, radula and body morphology. 511 samples containing 2593 specimens belonging to 11 different species were examined, 4 Chaetodermatidae, 2 Limifossoridae and 5 Prochaetodermatidae. Moreover, 2313 type specimens from 378 lots representing 33 nominal species, from National Museum of Natural History (USNM) and Museum of Comparative Zoology (MCZ) were also analyzed. Regarding the patterns of geographical distribution, it was observed that the Chaetodematidae and Limifossoridae usually have more restrict distribution in the Western Atlantic, whereas the Prochaetodermatidae usually have wider distributions. Therefore, it is a pioneer study, with animals that are still little known for the coast of Atlantic Ocean in relation to other molluscs, leading to a better understanding of these small animals at great depths (AU)