During a study on parasites of fish from cenotes (= sinkholes) in the Yucatan Peninsula, the following cestodes and acanthocephalans were found in 581 freshwater fish of 15 species: the cestodes Bothriocephalus acheilognathi Yamaguti, 1934, Bothriocephalus sp. (Bothriocephalidae), Nomimascolex sp. (Monticellidae), Proteocephalidea gen. sp. larv., Dendrouterina pa-pillifera (Fuhrmann, 1908) larv. and D. pilherodiae Mahon, 1956 larv. (Dilepididae), and the acanthocephalans Octospinifer-oides chandleri Bullock, 1957, Neoechinorhynchus golvani Salgado-Maldonado, 1978 (Neoechinorhynchidae), Polymorphus (syn. Arhythmorhynchus) brevis (Van Cleave, 1916) larv. (Polymorphidae), and an echinorhynchid larva. With the exception of B. acheilognathi, all tapeworms are found in Mexico for the first time; second-stage larvae of D. papillifera and D. pilherodiae from fish are reported for the first time.
The present paper comprises a systematic survey of helminths from 202 red groupers, Epinephelus morio (Valenciennes) (Pisces: Serranidae), the most important commercial marine fish in the region, collected from ten localities off the Yucatan Peninsula in the Gulf of Mexico during 1994-1996; two more helminth species were recorded from E. morio earlier. Thirty species of helminths were found: Monogenea 1, Cestoda 3, Trematoda 17, Nematoda 8, Acanthocephala 1. Of them, 15 species were adults, whereas 15 species were larval stages parasitizing piscivorous elasmobranch and teleostean fishes, birds and marine mammals as adults. A new didymozoid trematode, Allonematohnlhrium yucatanense sp. n., is described from the fins of this host. Most findings represent new host- and geographical records. Philometra margolisi, a nematode parasitizing the gonads, is undoubtedly the most important parasite affecting the reproduction of the host, endangering E. morio in aquaculture. Larval anisakid nematodes (Anisakis, Pseudoterranova, Hysterothylacium) recorded from the red grouper in the region of the southern Gulf of Mexico are important from the viewpoint of public health.
Examination of 4055 molluscs of 10 species from cenotes (= sinkholes) and other freshwater bodies in the Yucatan Peninsula, Mexico revealed the presence of-larval stages of 13 trematodes. The following species were found: Echinochasmus leopoldinae Scholz, Ditrich et Vargas-Vázquez, 1996, E. macrocaudatus Ditrich, Scholz et Vargas-Vázquez, 1996 (Echi-nostomatidae), Saccocoelioides sp. (? sogandaresi Lumsden, 1963) (Haploporidae), Crassicutis cichlasomae Manter, 1936, pleurolophocercous ophthalmocercaria sp. (Homalometridae), Ascocotyle (Ascocotyle) sp., Ascocotyle (Phagicola) nana Ransom, 1920 (Heterophyidae), Oligogonotylus manieri Watson, 1976 (Cryptogonimidae), Genarchella astyanactis (Watson, 1976) (Derogenidae), xiphidiocercariae sp. 1, 2 and 3 (Lecithodendriidae?), and furcocercaria gen. sp. (Fellodistomidae). The life-cycle of the derogenid Genarchella astyanactis was studied for the first time. It was found that it differs from that of G. genarchella: the first intermediate host, Pyrgophorus coronatus (Pfeiffer, 1839), released cystophorous furcocercariae of G. astyanactis that developed, after ingestion by the second intermediate host, copepods (experimentally Mesocyclops chaci Fiers, Reid, Ilife et Suárez-Morales, 1996), into metacercariae resembling by their morphology juvenile trematodes found in the stomach of Aslya-nax fasciatus. No progenetic cercariae (metacercariae) found in G. genarchella were observed in the life-cycle of G. astyanactis. Rediae and cystophorous furcocercariae were recovered from naturally infected snails and snails experimentally kept in contact with eggs from the uterus of G. astyanactis adults.
During a survey of the parasites of freshwater fishes from cenotes (sinkholes) of the Yucatan Peninsula the following species of monogeneans were found on cichlid, pimelodid, characid and poeciliid fishes: Sciadicleithrum mexicanum Kritsky, Vidal-Martinez et Rodriguez-Canul, 1994 from C.ichlasoma urophthalmus (Giinther) (type host), Cichlasoma friedrichsthali (Heckel), Cichlasoma octofasciatum (Regan), and Cichlasoma synspilum Hubbs, all new host records; Sciadicleithrum meekii Mcndoza-Franco, Scholz et Vidal-Martinez, 1997 from Cichlasoma meeki (Brind); Urocleidoides chavarriai (Price, 1938) and Urocleidoides travassosi (Price, 1938) from Rhamdia guatemalensis (Günther); Urocleidoides costaricensis (Price et Bussing, 1967), Urocleidoides heteroancistrium (Price et Bussing, 1968), Urocleidoides anops Kritsky et Thatcher, 1974, Anacanthocotyle anacanthocolyle Kritsky et Fritts, 1970, and Gyrodaclylus neotropicalis Kritsky et Fritts, 1970 from Aslyanax fasciatus; and Gyrodactylus sp. from Gambusia yucatana Regan. Urocleidoides chavarriai, U. travassosi, U. costaricensis, U. heteroancistrium, U. anops, Anacanthocotyle anacanthocotyle and Gyrodactylus neotropicalis are reported from North America (Mexico) for the first time. These findings support the idea about the dispersion of freshwater fishes and their monogenean parasites from South America through Central America to southeastern Mexico, following the emergence of the Panamanian isthmus between 2 and 5 million years ago.
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.