About 300 species belonging to four superfamilies (Gnathostomatoidea, Habronematoidea, Physalopteroidea and Thelazioidea) of the nematode suborder Spirurina are known as the adult parasites of freshwater, brackish-water and marine fishes. They are placed in four families, of which the Gnathostomatidae, including Echinocephalus with a few species and the monotypic Metaleptus, are parasites of elasmobranchs, whereas Ancyracanthus contains one species in teleosts; the Physalopteridae is represented in fish by four genera, Bulbocephalus, Heliconema, Paraleptus and Proleptus, each with several species in both elasmobranchs and teleosts. The majority of fish spirurines belongs to the Rhabdochonidae, which includes 10 genera (Beaninema, Fellicola, Hepatinema, Heptochona, Johnstonmawsonia, Megachona, Pancreatonema, Prosungulonema, Rhabdochona and Vasorhabdochona) of species parasitizing mainly teleosts, rarely elasmobranchs, and the Cystidicolidae with about 23 genera (Ascarophis, Caballeronema, Capillospirura, Comephoronema, Crenatobronema, Cristitectus, Ctenascarophis, Cyclozone, Cystidicola, Cystidicoloides, Johnstonmawsonoides, Metabronema, Moravecnema, Neoascarophis, Parascarophis, Prospinitectus, Pseudascarophis, Pseudoproleptus, Salvelinema, Similascarophis, Spinitectoides, Spinitectus, Sterliadochona), with many species parasitic in teleosts only. Because of difficulties in studying fish spirurines, associated with their morphological and biological peculiarities, most species of these parasites are poorly known. It is apparent that their present classification system does not reflect phylogenetic relationships and a taxonomic revision of this nematode group, based on detailed morphological (including SEM and TEM), life history and molecular studies of individual species, is quite necessary. In Cystidicolidae, several genera have been based on details in the cephalic structures visible only with the aid of SEM, but it will be evident whether or not these tiny features are of generic importance only when more cystidicolids are described using SEM and comparative molecular data become available. Data on the biology of fish spirurines are scarce. In known cases, their life cycles involve aquatic arthropods (crustaceans or insects) as intermediate hosts, in which, sometimes, the larvae undergo a precocious development and may even attain adulthood and become gravid in these invertebrates; sometimes, fish paratenic hosts are known to occur in cystidicolids parasitizing as adults piscivorous definitive hosts. Some spirurine species are pathogenic and are known as causative agents of serious fish diseases. and Consequently, further detailed studies on fish spirurines are significant not only from the theoretical viewpoint, but they may also have practical implications.
The nematode superfamily Dracunculoidea includes 166 recognized species, of which 150 (90%) are parasitic in about 300 species of freshwater, brackish-water and marine fishes. Fish dracunculoids are placed in 31 genera (86% of all dracunculoid genera) belonging to eight of the nine dracunculoid families: Anguillicolidae, Daniconematidae, Guyanemidae, Lucionematidae, Micropleuridae, Philometridae, Skrjabillanidae, and Tetanonematidae; the genus Lockenloia is considered incertae sedis. Because of difficulties in studying fish dracunculoids, associated with their morphological and biological peculiarities, most species of these largely histozoic parasites are poorly known and males of the majority of species and of eight genera have not yet been discovered. It is apparent that the present classification system of dracunculoids as a whole does not reflect phylogenetic relationships and a taxonomic revision of this nematode group, based on detailed morphological (including SEM and TEM), life history and molecular studies of individual species, is quite necessary. Data on the biology of fish dracunculoids is scarce. In known cases, their life cycles involve copepods, ostracods or branchiurids as intermediate hosts and, sometimes, fish paratenic hosts are known to occur in dracunculoid species parasitizing as adults piscivorous definitive hosts. However, nothing is known about the life cycles of representatives of 20 genera. Some species of dracunculoids, particularly of philometrids, are highly pathogenic and are known as agents of serious fish diseases. During recent years, especially the importance of Philometra spp. parasitizing the gonads of many species of marine fishes has increased due in particular to the rapid development of marine aquaculture, because they may significantly decrease fish reproduction or even cause full parasitic castration. Therefore, further detailed studies on fish dracunculoids are significant not only from the theoretical viewpoint, but they may also have practical implications.
Two new, one known and three unidentified species of the nematode family Camallanidae are reported and described from the intestines of marine perciform fishes off the southwestern coast of New Caledonia, South Pacific: Camallanus carangis Olsen, 1952 from the forked-tailed threadfin bream Nemipterus furcosus (Nemipteridae), the yellowstriped goatfish Upeneus vittatus and the whitesaddle goatfish Parupeneus ciliatus (both Mullidae) (new host records); Procamallanus (Spirocamallanus) variolae sp. n. from the white-edged lyretail Variola albimarginata (type host) and the blacktip grouper Epinephelus fasciatus (both Serranidae); Procamallanus (Spirocamallanus) longus sp. n. from the twotone tang Zebrasoma scopas (Acanthuridae); Procamallanus (Spirocamallanus) sp. 1 (female tail with 2 terminal spikes on a digit-like projection) from the speckled sandperch Parapercis hexophtalma (Pinguipedidae); Procamallanus (Spirocamallanus) sp. 2 (female tail with 1 spike on a digit-like projection) from the drab emperor Lethrinus ravus (Lethrinidae) and Procamallanus (Spirocamallanus) sp. 3 (female tail with a smooth digit-like protrusion) from the two-lined monocle bream Scolopsis bilineata (Nemipteridae). Camallanus paracarangis Velasquez, 1980 is synonymized with C. carangis. Several additional species of Camallanus from marine fish of the Indo-Pacific region may be synonymous with C. carangis as it has a poorly sclerotized left spicule and 3 small caudal projections on the tail of young (i.e., non-gravid) females. The fourth-stage larva of C. carangis is described for the first time. P. (S.) variolae differs from most similar species of this region mainly in the position (i.e., at level or posterior to the nerve ring) and shape of deirids. P. (S.) longus differs from the similar P. (S.) chaimha mainly in a different arrangement of postanal papillae, shape of the female tail, much longer right spicule (429 µm) and longer body of gravid females (38-55 mm). All Camallanus and Procamallanus (Spirocamallanus) spp. reported here represent the first records of camallanids from marine fishes in New Caledonian waters.
An examination of three specimens of the Morelet's crocodile, Crocodylus moreletii Duméril et Bibron, from the Lagoon of Celestún, Yucatan, Mexico revealed the presence of the following eight helminth species: Acanthostomum americanum (Pérez Vigueras, 1956), Pelaezia loossi (Pérez Vigueras, 1956), Telorchis sp. juv., Pseudoneodiplostomum groschafti sp. n. (all trematodes), Dujardinascaris helicina (Molin, 1860), Contracaecum sp. Type 2 larvae, Micropleura sp. and Paratrichosoma recurvum (Solger, 1877) (all nematodes). Pseudoneodiplostomum groschafti sp. n. is established by indication based on the description of specimens from Crocodylus rhombifer from Cuba, given by Groschaft and Baruš (1970). Acanthostomum acuti Caballero et Brennes, 1959 is considered a synonym of A. americanum. A. americanum and D. helicina are recorded for the first time from Mexico and Micropleura sp. is the first American representative of the genus recorded outside South America. Findings of A. americanum, Telorchis sp., P. groschafti, D. helicina and Micropleura sp. in C. moreletii represent new host records. Some observations on the early development of D. helicina are provided. All species, except for P. recurvum, are briefly described and illustrated and some problems concerning their morphology, taxonomy and geographical distribution are discussed.
The present paper comprises a systematic survey of nematodes based on helminthological examinations of 176 specimens of freshwater fishes, belonging to 22 species, from central China (mostly lakes in Hubei Province) collected during the autumn of 2001. The following six species were recorded: Procamallanus (Spirocamallanus) fulvidraconis Li, 1935, Camallanus cotti Fujita, 1927, Dentiphilometra monopteri Moravec et Wang, 2002, Pingus sinensis Hsü, 1933, Proleptinae gen. sp. larv., and Eustrongylides sp. larv. Data on their morphology, morphological variability, host range, prevalence, intensity and distribution are provided. SEM studies of P. fulvidraconis and larval Physalopterinae, used for the first time in these species, revealed some additional morphological details and made it possible to redescribe the former. In contrast to the existing description of P. fulvidraconis, this species was found to possess two spicules and a V-shaped gubernaculum with unequal arms (originally mistaken for the left spicule), as well as deirids, whose location can be considered an important taxonomic feature. Larvae of the Physalopterinae have not previously been reported from fishes in China. The finding of larval Eustrongylides in Paramisgurnus dabryanus represents a new host record. All but one nematode species from this zoogeographically interesting region are briefly described and illustrated.
Scanning electron microscopy of the cystidicolid nematode Ascarophis mexicana Moravec, Salgado-Maldonado et Vivas-Rodríguez, 1995 enabled the first detailed study of its cephalic structure. In contrast to most Ascarophis species, its pseudolabia are highly reduced and sublabia are unlobed and weakly developed. Similascarophis is considered a synonym of Ascarophis, to which two its species are transferred as A. maulensis (Muñoz, González et George-Nascimento, 2004) comb. n. and A. chilensis (Muñoz, González et George-Nascimento, 2004) comb. n.
Scanning electron microscopy (SEM) examination of a paratype specimen (gravid female) of the philometrid nematode Paraphilometroides nemipteri Moravec et Shaharom-Harrison, 1989, the type species of Paraphilometroides Moravec et Shaharom-Harrison, 1989, made it possible to recognise the true structure of the cephalic end and the shape of cuticular ornamentations on the body. In contrast to other philometrid genera, the cephalic end is angular in lateral view and rounded in dorsoventral view; large external cephalic papillae are fused together to form a marked dorsal and a ventral ala, each bent into a curve; six minute internal papillae, including a pair of previously not reported lateral papillae, were found; amphids were indistinct. Cuticular ornamentations (inflations) were found to be transversely elongated. These features, especially the unique cephalic structure, clearly distinguish Paraphilometroides from other philometrids and confirm the validity of this genus.
The systematic status of the gonad-infecting Philometra species previously reported as P. lateolabracis (Yamaguti, 1935) from marine fishes in the Mediterranean region and off New Caledonia is evaluated with respect to the recent redescription of P. lateolabracis from the type host in Japan. Philometra jordanoi (López-Neyra, 1951) is revalidated to accommodate the nematodes from Epinephelus marginatus, whereas the philometrids from other European hosts (Mycteroperca rubra and Seriola dumerili), as well as those from the gonads of Epinephelus cyanopodus and E. fasciatus off New Caledonia, should be reported as Philometra sp. until new data are available. Also the philometrids reported as P. lateolabracis from Parupeneus indicus from off Somalia should be designated as Philometra sp. for the time being.
Reexamination of the male holotype of the rhabdochonid nematode Rhabdochona leucaspii Kritscher, 1979, originally described from the intestine of the cyprinid fish Leucaspius prosperi [= Ladigesocypris ghigii (Gianferrari)] from Rhodes Island, Greece, confirmed its morphological and biometrical identity with Rhabdochona denudata (Dujardin, 1845), a common and widespread parasite of cyprinids and some other fishes in palaearctic Eurasia. Consequently, R. leucaspii is considered a junior synonym of R. denudata.
Examination of the original literature concerning species of Philometra (Philometridae, Dracunculoidea) parasitic in the abdominal cavity of European cyprinids revealed that P. abdominalis Nybelin, 1928 is a junior synonym of P. ovata (Zeder, 1803), a parasite of cyprinids of the genera Gobio, Phoxinus and Leuciscus. The valid name of the species parasitizing cyprinids of the genera Abramis, Rutilus and Vimba, mostly reported erroneously as P. ovata, is P. cyprinirutili (Creplin, 1825) comb. n.