A description is given of the life cycle of the nematode Procamallanus (Spirocamallanus) rebecae (Andrade-Salas, Pineda-Lopez et García-Magafia, 1994), an intestinal parasite of cichlids in Mexico. The copepod Mesocyclnps sp. was found to be a suitable experimental intermediate host. After the copepod’s ingestion of free first-stage larvae of the nematode, these enter the haemocoel of the intermediate host; they moult twice (on the 3rd and 5-6th day p.i. at 21-22”C) before they attain the third, infective stage. The third-stage larva already possesses the large buccal capsule without spiral thickenings and its tail tip bears three cuticular spines. The larvae undergo two additional moults (13-14 days and 42 days p.i.) in the definitive host (Cichlasoma urophthalmus) before changing to adults; the prepatent period is about 2-3 months. Experimental infection of guppies, Poecilia reticulata, have shown that these fishes may become paratenic (metaparatenic) hosts of this parasite. The morphology of individual larval stages of this nematode is described.
The development of the nematode Procamalianus (Spirocamallanus) neocaballeroi (Caballero-Deloya, 1977), an intestinal parasite of the characid fish, Astyanax fasciatus (Cuvier) in Mexico, was studied in the experimental copepod intermediate host, Mesocyclops sp. After the copepod’s ingestion of free first-stage larvae of the nematode, these penetrate into the haemocoel of the intermediate host; they moult twice (on the 3rd and 4-5th day p.i. at 21-22”C) before they attain the third, infective stage. The third-stage larva already possesses the large buccal capsule subdivided into an anterior broad portion with eight spiral thickenings (as observed in lateral view) and a narrow posterior portion, and its tail tip bears three conical processes. The definitive host acquires infection by feeding on infected copepods; in the intestine of this fish, the nematode larvae undergo two more moults (on the 10th and 14-15th day p.i. at 25-32°C) before attaining their maturity. The prepatent period is approximately two months.