Examinations of 29 specimens of the catfish Liobagrus reini Hilgendorf (Siluriformes: Amblycipitidae), a species endemic to Japan, collected from the Sho River, Toyama Prefecture, in central Honshu, revealed the presence of four species of helminth parasites: Plagioporus honshuensis sp. n. (Trematoda), Rhabdochona coronacauda Belouss, 1965, H. japonica Moravec, 1975 and Mexiconema liobagri sp. n. (all Nematoda). The new opccoelid trematode P. honshuensis is characterized mainly by the extent of vitelline follicles, the size ratio of the suckers (1 : 1.7-2.1), the situation of testes near the middle of the body and by the structure, size and shape of the cirrus sac. Allopodocotyle Pritchard, 1966 is considered a junior synonym of Plagioporus Stafford, 1904. The males of R. japonica are described for the first time and conspeciftc females are redescribed; this species is a specific parasite of L. reini. The principle hosts of R. coronacauda are cyprinids and, therefore, its finding in the catfish may indicate an accidental infection; L. reini represents a new host record. M. liobagri (only females were found) from the host’s abdominal cavily is the second known species of this dracunculoid genus, being characterized by the position of the excretory pore and the number (1) of caudal processes in the female. The recorded helminths are briefly described and illustrated and problems of their systematic status are discussed.
A new nematode, Myleusnema bicumis gen. et sp. п., is described from the intestine of a characoid freshwater fish, Myleus ternetzi (Norman, 1929) (Cypriniformes: Serrasalmidae), from French Guiana. This cosmocercoid nematode species represents a new genus of the family Kathlaniidae, being characterized mainly by the shape of the body (the cephalic portion is separated from the rest of the body at the level of the nerve ring), structure of the cephalic extremity (presence of three lips and three lamella-like formations demarcating the buccal cavity), absence of an oesophageal pharynx, presence of medium-sized alate spicules (0.694-0.721 mm long), two conspicuous postcloacal homs associated with a gubernaculum, and by the number and distribution of caudal papillae in the male.
A new kathlaniid nematode, Myleusnema brasiliense sp. n„ is described from the intestine of a characoid fish, Myleus sp. (Serrasalmidae, Cypriniformes), from Brazil, It differs from the only other congeneric species Myleusnema bicornis Moravec et Thatcher, 1996 mainly in having an unseparated cephalic portion of the body, lips provided with Hanges with numerous spikelike appendages, deirids situated more posteriorly, more numerous (8 pairs) subventral preanal papillae in the male, and distinctly longer spicules (1.58-1.70 mm). The species description is based on light microscopic and scanning electron microscopic (SF,M) observations.
The morphology of the nematode Klossinemella iheringi (Travassos, Artigas et Pereira, 1928), the type species of the genus Klossinemella Costa, 1961, was studied using specimens collected from the serrasalmid fish, Mylesinus paraschomhurgkii légu, Santos et Ferreira, 1989 (a new host record), from the Trombetas River, Para State, Brazil, by both light and scanning electron microscopy. This species was also recorded from the Jari River (Pará State), the Uatuma, Pitinga and Capucapu Rivers (Amazonas State), and the Araguari River (Amapá State). An examination by SEM made it possible, for the first time in this genus, to study in detail the structure of the cephalic end. Characteristic features are the presence of 8 cephalic papillae arranged in two circlets, well developed lateral amphids, and especially a crown of 8 cephalic, Y-shaped sclerotized pieces (outgrowths). The male possesses 8 pairs of caudal papillae (3 preanals, 1 adanal and 4 postanals), two unequal spicules (0.156-0.294 mm and 0.069-0.099 mm long) and a gubemaculum (0.027-0.045 mm in length); previously undescribed deirids were also found. This is the first record of this parasite from the Amazon River basin. The genus Proatractis G. Caballero, 1971 is considered a synonym of Klossinemella Costa, 1961, belonging to the cosmocercoid family Atractidae, and its type species is transferred to the latter genus as Klossinemella parvicapilico-rnnala (G. Caballero, 1971) comb. n.
A new cucullanid nematode, Dichelyne mexicanus sp. n., is described from the intestine of three species of fishes, Agonostomus monticola (Bancroft) (Mugilidae, Perciformcs) (type host), Ictalurus balsanus (Jordan et Snyder) (Ictaluridac, Siluriformes) and Cichlasoma beani (Jordan) (Cichlidae, Perciformes), from three rivers (la Maquina River, Veracruz; Chontalcoatlán River, Guerrero and Santiago River, Nayaril) in central Mexico. This species is characterised by the absence of a ventral sucker in the male (subgenus Dichelyne) and it differs from its congeners mainly in possessing very unequal and dissimilar spicules (left 0.465-0.768 mm and right 293-548 mm long), an asymmetrical gubernaculum, and two intestinal caeca. Another cucullanid nematode, Cucullanus cabaUeroi Petter, 1977, is reported from Dormitator maculalus (Bloch) (Eleotridae, Perciformes) from the La Palma and La Maquina Rivers and Balzapote stream, Veracruz, being briefly described and illustrated; this represents a new host record. Findings of D. mexicanus and C. cabalteroi represent a new record of cucullanid nematodes from fishes in Mexican fresh waters.
A new nematode, Rhabdochona mexicana sp. n., is described based on specimens recovered from the intestine of two species of fishes, Astyanax mexicanus (De Filippi) (type host) and Astyanax J'asciatus (Cuvier) (Characidae: Characiformes) in central Mexico. This species is characterised by the following characters: 10 anteriorly directed teeth in the prostom, a larger (left) spicule which is slender in form with a small bifurcation at its distal tip covered by a culicular membrane, a smaller (right) spicule without a barb at its distal tip, eggs bearing an irregular flock-like coaling, and a conical tail without a cuticular spike (in both sexes).
The morphology of the scoleces of 11 Proteocephalus species, parasites of freshwater fish in the Palaearctic Region, was compared using light and scanning electron microscopy. The following taxa were evaluated: Proteocephalus ambiguus (Dujardin, 1845); P. cernuae (Gmelin, 1790); P. exiguus La Rue, 1911; P. filicollis (Rudolphi, 1802); P. macrocephalus (Creplin, 1825); P. osculatus (Goeze, 1782); P. percae (Müller, 1780); P. pollunicola Gresson, 1952; P. sagitlus (Grimm, 1872); P. thymalli (Annenkova-Chlopina, 1923); and P. torulosus (Batsch, 1786). Some features as overall shape of the scolex, its size, shape and size of an apical sucker were found to be fairly stable and species-specific. The taxa more easily distinguishable from congeners on the basis of their scolex morphology were P. cernuae, P. macrocephalus, P. osculatus, P. percae and P. torulosus. The taxonomic importance of the scolex is discussed.