Rotifer Look-Alikes: Two Species of Colurella Are Ciliated Protozoans

Abstract

Some 19 valid species of in the genus Colurella have been described from all parts of the world, mostly from littoral or interstitial habitats of fresh and salt waters. Colurella monodactylos and C. althausae, described from marine interstitial sands of the Black Sea and Caribbean, respectively, are significantly different from their congeners. Although no type specimens were deposited for either species, published drawings or photographs provide enough evidence to conclude that both of these rotifers are in fact ciliated protists of the family Dysteriidae, probably of the genus Dysteria. Additional key words: protist, interstitial, benthic Rotifers of the genus Colurella BORY DE ST. VINCENT 1824 are small, mostly littoral or benthic animals belonging to the class Monogononta. Their morphology features a single-piece lorica, oval or rounded, laterally flattened, dorso-ventrally folded (as in a cladoceran), with internal ventral membrane (sulcus) between the lateral edges of the lorica. They have an anterior head, and a threeor four-segmented foot and two moderately long toes protruding postero-ventrally. Their corona has a membranous cap (Fig. la-d). At least 19 different species of Colurella have been described to date (Koste 1978; Kutikova & Arov 1985). Althaus (1957) described and figured an inhabitant of the psammon of the Black Sea with similar lorica shape, body dimensions, and apparent habitat as a rotifer of the genus Colurella. Its foot was obscured and the putative single toe protruded postero-ventrally as expected from a Colurella rotifer. No species of Colurella to that date had been described with a single