A new nematode species, Pseudocapillaria yucatanensis sp. n., is described from the intestine of the freshwater pimelodid catfish Rhamdia guatemalensis (Günther) from cenotes (= sinkholes) in Yucatan, Mexico. It differs from other three related species parasitizing freshwater fishes mainly in possessing the spicule with a simple rim of its proximal end and a non-expanded distal end, in the length of the spicule (0.218-0.295 mm), and the size (0.050-0.060 x 0.025-0.030 mm), shape and structure of eggs, and also in the host types and geographical distribution. Pseudocapillaria yucatanensis is the first known autochtonous species of Pseudocapillaria parasitizing freshwater fishes in Mexico.
The proteocephalid tapeworm Proteocephalus torulosus (Batsch, 1786) exhibited a marked seasonality in its occurrence and maturation in barbel (Barbus harhus L.) from the Jihlava River, South Moravia, Czech Republic. Recruitment took place in winter and early spring, growth and maturation in spring and gravid worms left the fish hosts in May; during summer and autumn, the parasite was almost absent from the fish population. Parasite burden was related to fish size, with larger barbel being more heavily infected than smaller ones.
Three species of planktonie crustaceans, Cyclops strenuus and Macrocyclops alhidus (Copcpoda) and Notodromas monacha (Ostracoda), were experimentally infected with the eggs and second-stage larvae of the swimbladder nematode Anguillicola crassus originating from eels from Neusiedler Lake in Austria. At 20-22°C, third-stage larvae of the parasite developed in all these invertebrate hosts within 16-20 days p.i. Ostracods harbouring the nematode third-stage larvae (33 days p.i.) were fed to small eels (Anguilla anguilla), while infected copepods (20 days p.i.) to seven other fish species. By these experiments, the larvae from ostracods proved to be infective for the definitive host and the ostracod was thus confirmed as a true intermediate host of Anguillicola crassus. Notodromas monacha represents a new experimental intermediate host of A. crassus and the second known invertebrate other than a copepod in which the larval development of this nematode up to the infective stage takes place. Five species of fish, cyprinids Tinca tinea, Alhumus alburnus, Gobio gobio and Albumoides bipunctatus (the latter representing a new host record), and guppy, Poecilia reticulata, were found to serve as experimental paratenic hosts for A. crassus, in which the live nematode infective larvae were recorded 49 days p.i.
The development of the nematode Anguillicola crassus, a swimbladder parasite of eels, was experimentally studied in copepod intermediate hosts Cyclops strenuus and Acanthocyclops vernalis. The copepods, kept at a laboratory temperature of 20-22 °C, were infected with nematode second-stage larvae; the second moult of larvae (the only one in the intermediate host) was observed to start 10 days p,i„ but third-stage larvae liberated from their cuticular sheath were first observed 20 days p.i. These proved to be infective for experimental eels. Free second-stage larvae as well as larvae from copepods were described. The morphology of A. crassus larvae and the mode of their development in the intermediate host were compared with those of other dracunculoid nematodes. From this point of view, Anguillicola members appear to represent an ancient group of dracunculoid nematodes.
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.
Daniconema anguillae Moravec et Koie, 1987 larvae measuring 1.64-1.76 mm were occasionally found in considerable numbers in the fins and subcutaneous connective tissue of approximately 50% of eel Anguilla anguilla (L.) sampled from Lake Balaton, Hungary. The larvae were noted for their slender body, very long tail with a rounded tip, a densely transversely striated cuticle, and the presence of boring tooth and large kidney-shaped amphids on the cephalic end. The larvae could easily be recovered from the above mentioned organs by placing them into isotonic saline solution. No disease signs or pathological changes attributable to the larval infection could be observed. The only histological indication of host reaction was the appearance of macrophages adhering to the body surface of larvae and of cells with spherical nucleus in areas around the larvae. A possible life cycle pattern of I), anguillae is discussed.
Examination of freshwater fishes from the Parana River in southern Brazil during March 1992, revealed the presence of two new, previously undescribed species of the genus Goezia: G. brasiliensis sp. n. is described from the stomach of Brycon hilarii (family Characidae) (type host) and the intestine of Pseudoplatystoma coruscans (Pimelodidae) and it is characterized mainly by the length (0.802 mm) of spicules, number and arrangement of male caudal papillae (10 pairs of preanals and 4 pairs of postanals) and body measurements (male 11 mm, female 10-16 mm); the main characteristics of G. brevicaeca sp. n„ described from the stomach of Brycon hilarii, are a short anterior intestinal caecum reaching anteriorly only to the posterior end of oesophagus, comparatively short spicules (0.367 mm), number of male caudal papillae (20 pairs of preanals and 4 pairs of postanals) and an elongate, rather long body (male 17 mm, female 23 mm).