Catatropis johnstoni Martin, 1956

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 : 470

Catatropis johnstoni Martin

(4. Cajo; Figs. 1 , 15–18 )

Diagnosis: Parthenitae. Colony comprised of barely active rediae, densely concentrated in snail mantle (in enlarged perirectal sinus). Rediae translucent orange, yellow, or colorless; ~ 500–900 µm long, pyriform, ovoid to elongate (length:width up to ~8:1), often narrows anteriorly.

Cercaria . Body opaque tan when developed, opaque white with anterior diffuse black transverse band (eye pigment) when younger; oculate, often with a weak median pigment spot; with oral sucker and no ventral sucker; with one pair postero-lateral “adhesive glands”, but these not consistently obvious; with main excretory ducts connecting near eyes to form a ring (“cyclocoel”); body ~ 350 µm long, ~equal in length to tail; tail simple.

Cercaria behavior: Fresh, emerged cercariae remain in water column, swim intermittently with periods of resting; readily encyst on snail shell and operculum, dissection dish, or inside pipettes during transfer.

Similar species: Cajo could possibly be confused with the himasthlid Hirh [6], but it is readily distinguished by lacking a ventral sucker, lacking a spined collar, having a cyclocoel excretory system, and having the redia colony locus in the mantle.

Remarks: Martin (1956) documented the life cycle. He described the sporocysts, cercariae, metacercariae, and adults obtained by experimentally infecting young domestic chickens.

Mature, ripe colonies comprise ~22% the soft-tissue weight of an infected snail (summer-time estimate derived from information in [ Hechinger et al. 2009]).

Cajo does not have a physical caste of soldier rediae (Garcia et al., submitted).

Cercariae do a substantial amount of development after they leave the rediae, but before they leave the snail ( Martin 1956).

Cajo appears to make infected snails much more likely to die under stressful conditions, as we have qualitatively noted for years, and as indicated by a re-analysis of Sousa and Gleason’s (1989) data ( Hechinger et al. 2009).

Figures

FIGURE 1. General characteristics of the parthenitae and cercariae of the trematodes infecting Cerithideopsis californica as first intermediate host. Species numbers and codes follow Table 1 and species accounts. Cercariae are all to scale, with additional magnified views of six small species (indicated by dashed lines). Note the oral stylets (presented in right lateral view) for Pruc and Smmi. Parthenitae are not to scale. Scale bars consistently indicate 100 µm.

FIGURES 15–18. Catatropis johnstoni (Cajo). 15, Overview of a colony in a freshly deshelled, infected female horn snail in sea water. The arrow indicates the colony, which is localized in the mantle. Scale bar = 1 cm. 16, Redia, live, with developing cercariae, under coverslip pressure. Scale bar = 100 µm. 17, Cercariae, live, showing ontogenetic variation of cercariae present after they have left rediae. Scale bar = 100 µm. 18, Close-up of cercaria body, live, under slight coverslip pressure to better reveal key traits. Scale bar = 100 µm.