DESCRIPTION, REDESCRIPTION, AND LIFE CYCLES OF CLOACITREMA KURISI N. SP. AND CLOACITREMA MICHIGANENSIS (TREMATODA: DIGENEA: PHILOPHTHALMIDAE) FROM THE CALIFORNIA HORN SNAIL, CERITHIDEOPSIS CALIFORNICA (GASTROPODA: POTAMIDIDAE).

Abstract

We describe the parthenita colonies, soldier rediae, reproductive rediae, cercariae, metacercariae, and sexual adults of Cloacitrema michiganensisMcIntosh, 1938 and Cloacitrema kurisi n. sp. using material from natural and experimental infections and molecular-genetic analyses. Cloacitrema kurisi, a "pseudo-cryptic" species, was previously pooled with C. michiganensis in research involving the guild of trematodes infecting the California horn snail, Cerithideopsis californica (Haldeman, 1840), as a first intermediate host. Our morphological data suggest that C. kurisi contaminated an earlier description of the C. michiganensis life cycle based on that same snail host. Our descriptions of all life stages use material originating from naturally infected, lab-maintained horn snails from San Diego, California. By repeatedly shedding cercariae from specific, labeled snails, we obtained material for experimental infections, developmental studies, and genetics. In all cases, these data were matched to individual first-intermediate host colonies. These same colonies were finally dissected to describe the morphology, behavior, and demographics of reproductive and soldier rediae. Metacercaria descriptions came from cercariae shed and encysted in the laboratory; we also document a metacercaria developmental time series for each species. We experimentally exposed final host chickens (Gallus gallus domesticus) and ducks (Anas platyrhynchos domesticus) to metacercariae per cloaca; we successfully obtained and described sexual adults only from the chickens. Both cytochrome c oxidase subunit 1 (COI) and 28S phylogenetic analyses corroborated that these are 2 Cloacitrema species. As indicated in its original description, C. michiganensis adults can be readily distinguished from other Cloacitrema species by the combination of their inter-cecal uterus; small, oval pharynx; large, equatorial ventral sucker; and the presence of inter-testicular space. The C. kurisi adult stage can be distinguished from other Cloacitrema species by the combination of its extra-cecal, post-testicular uterus; particularly large, round pharynx; the complete absence of an esophagus; and the presence of inter-testicular space. We use our morphometric data to provide an emended diagnosis for the genus Cloacitrema. There are now 10 formally named species of Cloacitrema, 4 of which have had their first intermediate host stages described.