Attachment of Myzobdella lugubris (Hirudinea: Piscicolidae) to Logperch, Percina caprodes, and brown bullhead, Ictalurus nebulosus

Attachment of Myzobdella lugubris to logperch (Percina caprodes) and brown bullhead (Ictalurus nebulosus) is described. Leeches usually are firmly attached to fins with the caudal sucker molded over a fin ray. The leech body is always directed posteriorly over the surface of the fins. Host tissue surrounding the leech attachment site is raised due to epithelial hyperplasia and hypodermal thickening. In brown bullhead, dilated blood vessels and hemorrhage are present around the attachment site, and hemorrhage occurs at the margins of the fin rays where the caudal sucker erodes the dermis. Epithelium is absent at the site of attachment in both fish species. An acellular layer is present between the caudal sucker and host tissues, and apparently is formed from secretions of several types of leech gland cells. The adhesion of the leech at the unprotected site on the fins probably is enhanced by the leech's body orientation which minimizes water resistance, caudal sucker secretions which likely complement suctorial pressure, and close concordance of the caudal sucker with the firm substrate provided by the fin ray. Localization of M. lugubris on the fins of the fishes may be determined in part by the preferred attachment of the caudal sucker to the fin rays.