A New Protozoan of the Genus Cothurnia (Ciliophora, Peritrichia), Epibiont on the Marine Tanaid Halmyrapseudes spaansi (Crustacea Peracarida) from the French Guiana (SE America)

Specimens of the marine tanaid crustacea Halmyrapseudes spaansi, sampled in temporary littoral muddy patches near the mouth of the Kaw river (French Guiana, SE America), showed protozoan epibionts herein described as a new species: Cothurnia guyanensis sp. n. (Ciliophora, Peritrichia). These ciliates were covered by a cylindrical or bell-shaped lorica containing an oval elongated zooid with a rounded contractile vacuole located anteriorly in lateral position. The macronucleus was “S” shaped. The peristomial disk was anterior and included a polikinety and a haplokinety. The external stalk was short and broad, with 8–18 longitudinal conspicuous striations. Between the external stalk and the zooid, there were an endostyle and an mesostyle both short and broad. The striations of the external stalk were prolonged in the mesostyle. Telotroch stages were observed and described, as well as specimens with two zooids per lorica. Epibionts located on the ventral area, pereopods and antennae of the basibiont.