Cloacitrema michiganensis McIntosh, 1938

Hechinger, Ryan F., 2019, Guide to the trematodes (Platyhelminthes) that infect the California horn snail (Cerithideopsis californica: Potamididae: Gastropoda) as first intermediate host, Zootaxa 4711 (3), pp. 459-494 : 475-476

Cloacitrema michiganensis McIntosh

(8. Clmi; Figs. 1, 30–33)

Diagnosis: Parthenitae. Colony comprised of active rediae, densely concentrated in snail gonad region with dispersion into basal visceral mass. Rediae translucent white to colorless, often with prominent pigmented gut; when filled with cercariae, rediae appear opaque white; ~ 1000–2000 µm long, oblong to elongate (length:width up to ~6:1), often tapers in width gradually toward anterior and posterior ends, with posterior appendages that are often not pronounced.

Cercaria . Body opaque white, usually translucent colorless through ventral sucker; non-oculate; with oral and ventral sucker; with very short esophagus that bifurcates far anterior of ventral sucker (just posterior to pharynx); body ~ 425 µm long, ~equal in length to tail; tail with distal gland (tip appears invaginated).

Cercaria behavior: Fresh, emerged cercariae remain in water column, lengthen body and swim by rapidly ventrally folding body with tail extended (often forming a graceful, undulating S), and will often encyst on dissection dish or in pipette during transfer.

Similar species: Clmi is most readily distinguished from the only other philophthalmid (Pasp [9]) by having almost no esophagus anterior to the gut branching; Clmi also lacks tegumental spines, but these are sometimes difficult to see on Pasp, so be wary of using this as a sole distinguishing trait. Like Pasp, Clmi is easily separated from the himasthlids by having a distal tail gland.

Remarks: LeFlore et al. (1985) document the life cycle (see also Robinson (1952) and Martin [1972]), describing the miracidia, rediae, cercariae, metacercariae, and experimentally obtained adults, which they identified as Cloacitrema michiganensis , which was originally described from eastern North American shorebirds.

Mature, ripe colonies comprise ~24% the soft-tissue weight of an infected snail (summer-time estimate derived from information in [ Hechinger et al. 2009]).

Infection causes (stolen) snail bodies to grow ~ 2x faster than uninfected snails ( Hechinger 2010).

This species has a caste of soldier rediae (noted in Hechinger et al. (2011b) and carefully documented in Garcia- Vedrenne et al. [2016]).

Nadakal (1960b) presents information on the pigments of the rediae and cercariae of this species.