“Minute” species of Cochliopodium (Himatismenida): Description of three new fresh- and brackish-water species with a new diagnosis for Cochliopodium minus Page, 1976

Only two species of Cochliopodium below 20 μm in size are currently known. These are the recently described marine Cochliopodium gallicum Kudryavtsev and Smirnov, 2006 and a freshwater C. minutum West, 1901, an incompletely described species that has never been re-isolated since its initial description. In this paper, the descriptions of three independent species of similar size below 20 μm, C. minutoidum, C. kieliense, and C. maeoticum are presented. In the light microscope they all resemble the description of C. minutum, C. minutoidum being most similar to this species. However, the available description of C. minutum is inadequate to permit the assignment of any strain to this species with confidence. Therefore, a status of nomen dubium is proposed for C. minutum. Furthermore, C. minutoidum appears to be very similar to a fish endobiont identified by Dyková et al. (1998. Cochliopodium minus, a scale-bearing amoeba isolated from organs of perch Perca fluviatilis. Dis. Aquat. Org. 34, 205–210) as C. minus. Direct comparison of my strain of C. minutoidum with the type strain of C. minus suggests that it is not identical to C. minus. The obtained data enabled me to add the ultrastructural features to the diagnosis of C. minus for more precise identification of this species.