Redescription of Myxobolus rhinichthidis (Myxosporea) parasitizing Rhinichthys cataractae, with a revised taxonomic list of species of Myxobolus known from North American freshwater fishes

Abstract

Myxobolus rhinichthidis Fantham, Porter and Richardson, 1939 (Myxosporea) is redescribed from longnose dace (Rhinichthys cataractae) in Maryland. Large round plasmodia occurred in the connective tissue of the skin covering the head and opercular regions. Fixed spores are oval in front view and measure 11.5–14.5 μm long, 9.0–10.5 μm wide, and 6.0–7.0 μm thick. The polar capsules are 5.5–7.0 μm long and 3.0–3.5 μm wide. Photomicrographs of formalin-fixed spores document variation in spore size and shape. The report is the first for M. rhinichthidis since the species was described from blacknose dace (Rhinichthys atratulus) in Quebec. An updated list of species of Myxobolus Bütschli, 1882 reported from freshwater fishes in North America is provided. Myxobolus jahnricei Landsberg and Lom, 1991 is considered a junior synonym of Myxobolus filamentus Grinham and Cone, 1990; and Myxobolus lii Desser, 1993 and Myxobolus gibbosus Li and Desser, 1985 are junior synonyms of Myxobolus uvuliferus Cone and Anderson, 1977.