A New Species of Myxobolus (Cnidaria: Myxosporea: Myxobolidae) from the Mesenteries of Blackspotted Topminnow, Fundulus olivaceus (Cyprinodontiformes: Fundulidae), from the Upper Ouachita River Drainage, Arkansas, USA

Between March and August 2024, three species of Fundulus topminnows, including two northern studfish, Fundulus catenatus, six blackspotted topminnows, Fundulus olivaceus, and eleven blackstriped topminnows, Fundulus notatus, were collected from various Ouachita River drainage watersheds in Arkansas, USA. They were examined for myxozoans by having their gill, gallbladder, fins, integument, mesenteries, musculature, and other major organs examined. The mesenteries of two (33%) F. olivaceus from Town Creek (Fulton County, Arkansas, USA) were infected with a new myxozoan, Myxobolus storeri sp. n. Molecular data consisted of a 1726 base pair sequence of the partial small subunit ribosomal RNA gene for M. storeri sp. n. Histologically, plasmodia were limited to mesenteric adipose and hepatic parenchyma, causing slight compression of neighboring tissue but producing no associated inflammatory response in the examined histosections. This is the first time a myxozoan has been described from F. olivaceus and is the seventh species recorded from any member of the fish family Fundulidae.