UC San Diego

The California horn snail, Cerithideopsis californica, serves as first intermediate host to one of the best studied guilds of trematode parasites. This guild, and the individual species that comprise it, have been used as a model system for many ecological studies (see references herein). These marine parasite species have multiple-host complex life cycles and are an important part of salt marsh food webs (Lafferty & Kuris 2009; Kuris et al. 2008). Despite the trematodes’ widespread presence throughout the literature, several members of the guild have not been accurately identified, formally described, or had their life cycles resolved. Proper taxonomic naming and identification is important, particularly because we know that some of the guild members are composed of several cryptic species (e.g. Huspeni 2000). In this thesis, I provide formal descriptions of the colony demographics, parthenitae, and cercariae of Cloacitrema michiganensis (Philophthalmidae), Cloacitrema kurisi n.sp. (Philophthalmidae), Parorchis catoptrophori (Philophthalmidae), Parorchis laffertyi n.sp. (Philophthalmidae), Cercocyathocotylida intexens n.gen. n.sp. (Cyathocotylidae), and Probolocoryphe uca (Microphallidae). I also note the presence of an unrecognized Probolocoryphe (Microphallidae) species in California wetlands and provide genetic confirmation that the undescribed “small microphallid” (see Hechinger 2019) belongs in the genus Maritrema (Microphallidae). When possible, I describe the metacercariae and adults of these species obtained via experimental infections. Through analyses of their morphology and genetic data (at the CO1 and 28S loci) I elucidate the life cycles and assign proper taxonomic names to these species to enable them to be appropriately included into food webs and future ecological studies.