Levinseniella deblocki, New Species (Trematoda: Digenea: Microphallidae) from Salt Marshes along the Eastern Gulf of Mexico with Notes on Its Functional Morphology and Life History

Abstract

Levinseniella (Austromicrophallus) deblocki, n. sp., was collected during parasitologic studies of homeothermic vertebrates from salt marshes along the coast of the eastern Gulf of Mexico. Because L. deblocki lacks a femal epouch, it belongs to the subgenus Monarrhenos proposed by Deblock and Pearson (1970). However, since Deblock and Pearson did not explicitly designate a type species for Monarrhenos, it is not available and is a nomen nudum. The next available name, Austormicrophallus Szidat, 1964, a genus synonymized with Levinseniella Stiles and Hassall, 1901 by Deblock (1978), is reinstated as a subgenus to receive the species lacking a female pouch and previously assigned to Monarrhenos. The adult of L. deblocki is found in the lower digestive tracts of the clapper rail (Rallus longirostris), rice rat (Oryzomys palustris), and raccoon (Procyon lotor). Morphologically, L. deblocki appears to be most similar to L. polydactyla Deblock and Rose, 1962, known from Europe, and L. ophidea (Nicol, Dameree, and Wootton, 1985), described from a freshwater habitat in California. Differences in the life cycle, habitat type, and geographic distribution, plus a combination of distinctive morphological characters (presence of lappets on the oral sucker, number of genital pockets, and body size) separate L. deblocki from the other members of the subgenus Austromicrophallus. The metacercarial stage of L. deblocki occurs in the gonads of fiddler crabs (Uca spp.) and the fist intermediate host appears to be a hydrobud gastropod (Heleobops sp.). Observations on living and preserved specimens fixed in copula indicate that the genital atrium functions as an eversible hermaphroditic organ bearing the male papillae and metraterm. The genital hooks or “Jägersköld’s bodies” appear to function as holdfast structures during copulation.