Nelson Alexandria P, Metz Daniel C G, Hechinger Ryan F
Scripps Institution of Oceanography Marine Biology Research Division, University of California San Diego, 8622 Kennel Way, La Jolla, California 92037.
Current address: North Carolina State University Department of Applied Ecology, 100 Eugene Brooks Avenue, Campus Box 7617, Raleigh, North Carolina 27695.
J Parasitol. 2025 Jul 1;111(4):393-411. doi: 10.1645/24-41.
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.
我们利用来自自然感染和实验感染的材料以及分子遗传学分析，描述了密歇根泄殖吸虫（Cloacitrema michiganensis McIntosh，1938）和库里泄殖吸虫（Cloacitrema kurisi n. sp.）的孤雌生殖群体、兵雷蚴、生殖雷蚴、尾蚴、后尾蚴以及有性成虫。库里泄殖吸虫是一种“假隐性”物种，在以往涉及感染加州角螺（Cerithideopsis californica (Haldeman, 1840)）作为第一中间宿主的吸虫类群研究中，它曾与密歇根泄殖吸虫归为一类。我们的形态学数据表明，库里泄殖吸虫干扰了基于同一螺类宿主对密歇根泄殖吸虫生命周期的早期描述。我们对所有生活阶段的描述使用了源自加利福尼亚州圣地亚哥自然感染、实验室饲养的角螺的材料。通过反复从特定的、标记的螺中排出尾蚴，我们获得了用于实验感染、发育研究和遗传学研究的材料。在所有情况下，这些数据都与单个第一中间宿主群体相匹配。最终解剖这些相同的群体，以描述生殖雷蚴和兵雷蚴的形态、行为和种群统计学特征。后尾蚴的描述来自实验室排出并包囊化的尾蚴；我们还记录了每个物种的后尾蚴发育时间序列。我们通过泄殖腔将后尾蚴实验性地暴露于终末宿主鸡（Gallus gallus domesticus）和鸭（Anas platyrhynchos domesticus）；我们仅成功地从鸡中获得并描述了有性成虫。细胞色素c氧化酶亚基1（COI）和28S系统发育分析均证实这是两种泄殖吸虫物种。如最初描述所示，密歇根泄殖吸虫成虫可通过其盲肠间子宫、小的椭圆形咽、大的赤道腹吸盘以及睾丸间间隙的组合，很容易地与其他泄殖吸虫物种区分开来。库里泄殖吸虫成虫阶段可通过其盲肠外、睾丸后的子宫、特别大的圆形咽、完全没有食管以及睾丸间间隙的组合，与其他泄殖吸虫物种区分开来。我们利用形态测量数据对泄殖吸虫属进行了修订诊断。目前有10个正式命名的泄殖吸虫物种，其中4个已描述了其第一中间宿主阶段。
