THE DEVELOPMENT OF PROCAMALLANUS (SPIROCAMALLANUS) NEOCABALLEROI (NEMATODA, CAMALLANIDAE), A PARASITE OF ASTYANAX-FASCIATUS (PISCES) IN MEXICO

The development of the nematode Procamallanus (Spirocamallanus) neocab alleroi (Caballero-Deloya, 1977), an intestinal parasite of the charac id fish, Astyanax fasciatus (Cuvier) in Mexico, was studied in the exp erimental copepod intermediate host, Mesocyclops sp. After the copepod 's ingestion of free first-stage larvae of the nematode, these penetra te into the haemocoel of the intermediate host; they moult twice (on t he 3rd and 4-5th day p.i. at 21-22 degrees C) before they attain the t hird, infective stage. The third-stage larva already possesses the lar ge buccal capsule subdivided into an anterior broad portion with eight spiral thickenings (as observed in lateral view) and a narrow posteri or portion, and its tail tip bears three conical processes. The defini tive host acquires infection by feeding on infected copepods; in the i ntestine of this fish, the nematode larvae undergo two more moults (on the 10th and 14-15th day p.i. at 25-32 degrees C) before attaining th eir maturity. The prepatent period is approximately two months.