''Catatropis johnstoni'' is a

fluke Fluke may refer to: Biology * Fluke (fish), a species of marine flatfish * Fluke (tail), the lobes of the tail of a cetacean, such as dolphins or whales, ichthyosaurs, mosasaurs Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ...

from the United States. It was first described in 1956 by Martin, who had found cercariae (a larval stage of a fluke) released by the snail '' Cerithidea californica'' in southwestern California. When the cercaria were fed into chickens (''Gallus gallus domesticus''), they developed into mature worms; Martin speculated that the natural host was a waterbird. In 1970, a study of helminths of the

marsh rice rat The marsh rice rat (''Oryzomys palustris'') is a semiaquatic North American rodent in the family Cricetidae. It usually occurs in wetland habitats, such as swamps and salt marshes. It is found mostly in the eastern and southern United States, fr ...

(''Oryzomys palustris'') in a saltmarsh at Cedar Key, Florida, found flukes similar to ''C. johnstoni''.Bush and Kinsella, 1972, p. 843 The fluke was present in 30% of 110 examined rice rats, with the number of worms per rat varying from 1 to 500 (average 91).Kinsella, 1988, table 1 Some '' Cerithidea scalariformis'' snails from this marsh also released cercariae similar to ''C. johnstoni'' from California. When introduced into chickens, marsh rice rats,

Mongolian gerbil The Mongolian gerbil or Mongolian jird (''Meriones unguiculatus'') is a small rodent belonging to the subfamily Gerbillinae. Their body size is typically , with a tail, and body weight , with adult males larger than females. The animal is us ...

s (''Meriones unguiculatus''), golden hamsters (''Mesocricetus auratus''), and house mice (''Mus musculus''), these cercariae developed into infectious flukes.Bush and Kinsella, 1972, p. 844 Bush and Kinsella, who reported on the result in 1972, regarded the Florida and California flukes as the same species, as there were only minor size differences between them. Because no marsh-inhabiting rodent occurs in both California and Florida, they agreed with Martin that the normal host of ''C. johnstoni'' was most likely a bird, perhaps a rail or shorebird. Nevertheless, the rate of infection in the rice rat is too high for it to be just an accidental host; perhaps ''C. johnstoni'' is restricted to saltmarshes but not host-specific.Bush and Kinsella, 1972, p. 845 ''Catatropis johnstoni'' lacks a series of lateral papillae (nipple-like structures) on the underside, which are normally present in ''Catatropis''. In this character, it resembles the Australian '' C. nicolli'', which has the

genital pore A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, a ...

located further to the front. ''C. johnstoni'' does have a median ridge on the underside, another character of ''Catatropis'', but unlike in all other species of the genus, this ridge is not smooth, but consists of a series of distinct but closely spaced papillae. Because of this character, it may not in fact belong in ''Catatropis''.Cribb, 1991, p. 236

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Literature cited

* * * {{Taxonbar, from=Q2941714 Animals described in 1956 Plagiorchiida