Crasiella fonseci, a new species of Gastrotricha (Macrodasyida, Planodasyidae) from São Paulo, Brazil

Abstract

A new gastrotrich species of the genus Crasiella (Macrodasyida: Planodasyidae) is described from sublittoral sands of Ilha do Tamandua (Caraguatatuba, Sao Paulo), Brazil. Crasiella fonseci n. sp. is up to 560 μm long and differs from its congeners in its unique trilobed head shape, distinct indentation at the pharyngeal pores, and the presence of reinforcing rods in the caudal pedicles. Adhesive tubes are only present in ventrolateral and posterior series. The ventrolateral adhesive tubes are of multiple sizes and form two slightly-staggered columns down the length of the body. Tubes of the pharyngeal region are short, stout, and protrude laterally, while most tubes of the trunk region are distinctly thinner, more flaccid, and project posteriorly. Caudally, the tubes are again stouter and project laterally. Seven posterior adhesive tubes are borne on a pair of small caudal pedicles that are reinforced internally with rods. Animals are simultaneous hermaphrodites with a small frontal organ and large, apparently non-muscular caudal organ. This is the first report of the genus from South American waters.