Brazilian Caudofoveata (Mollusca, Aplacophora): a morphological analysis based on histology

Abstract

The Aplacophora are vermiform mollusks that, instead of having shells, have their bodies covered by a chitinous cuticle that harbors sclerites made of aragonite. They are divided into two lineages: Solenogastres Gegenbaur, 1878, and Caudofoveata Boettger, 1956. The Caudofoveata have 140 described species and are characterized by the absence of a foot and the presence of an oral shield surrounding the mouth. In Brazil, the first records of Caudofoveata were made by Scheltema (1985) and Ivanov and Scheltema (2008) for the northern and northeastern coasts of the country. However, more recently, a rich and diverse fauna of Caudofoveata has been described from a series of samplings that have occurred in oil-rich areas in the southern and southeastern regions of Brazil since the past decade. Additionally, another eight species have been recorded for the region. Despite these findings, little is known about the internal tissues of these animals, as studies have mainly focused on their external morphological characteristics, such as body shape, spicule details, and radula characters. Therefore, this Master's Project aims to analyze the anatomical characteristics of caudofoveates using histology techniques and comparing the internal structures among different families.