The present paper comprises a systematic survey of nematodes of the superfamily Seuratoidea collected from fishes of the Paraná River, southern Brazil, in 1992-1995. The following species were recorded: Neoparaseuratum travassosi Moravec, Kohn et Fernandes, 1992, Speaalus sp., Seuratoidea gen. sp. larvae, Cucullanus brevispiculus Moravec, Kohn et Fernandes, 1993, C. pinnui pinnai Travassos, Artigas et Pereira, 1928, C. pinnai plemdorasi subsp. n., C. rhamphichthydis sp. n., C. zunga-ro Va/, et Pereira, 1934, and Dichelyne pimelodi sp. n. C. pinnai pterodorasi (type host Plerodoras granulosus) differs from C. p. pinnai in the shape of the oesophagus and in the position of the nerve ring. C. rhamphichthydis (only females) (type host Rhamphichthys rostratus) is characterized mainly by the postoesophageal position of the excretory pore and deirids, complex structure of the cuticular lining of oesophastome and by markedly narrow body, whereas D. pimelodi (one male) (type host Pimelodus sp.) by the length of spicules (1.46 mm), postoesophageal position of the excretory pore and deirids and by the arrangement of genital papillae. Most species are briefly described (females of C. brevispiculus and Seuratoidea gen. sp. larvae for the first time) and illustrated and some problems concerning their taxonomy, hosts and geographical distribution are discussed.
Three hitherto unknown oxyuroid nematode species of the family Pharyngodonidae are described from the intestine of South American freshwater fishes, two of them being established as species new to science: Spinoxyuris annulata sp. n. from Myleus ternetzi (Norman) (Serrasalmidae) from French Guiana (Sinnamary River) and Ichthyouris ovifilamentosa sp. n. from Cichlasoma sp. (Cichlidae) from Amazonas (Negro River, São Gabriel da Cachoeira), Brazil. A third species, recovered from the same host as the latter (Cichlasoma sp.), was identified only as Ichthyouris sp. because of the absence of the male, although it probably also represents a new species. S. annulata differs from the only other congeneric species, S. oxydoras Petter, 1994, mainly in the absence of egg filaments, the location of an unpaired postanal papilla in the male, a distinctly longer spicule, and in an approximately double length of the body. Ichthyouris ovifilamentosa is closest to I. ro Inglis, 1962, differing from it principally in the structure of the cephalic end, the position of the excretory pore, and in the presence of filamented eggs. Ichthyouris sp. females differ from their congeners mainly in a characteristic structure of the cephalic end, the extent of lateral alae and the shape of their posterior ends, and in the character of egg filaments.
Recent examinations of marine perciform fishes from off the Florida coast in the Gulf of Mexico and Straits of Florida, USA, revealed the presence of the following six species of Philometra Costa, 1845 (Nematoda: Philometridae): P. haemulontis sp. n. (males and females) from the ovary of Haemulon plumierii (Lacepède) (type host) and H. aurolineatum Cuvier (both Haemulidae); Philometra synagridis Moravec, Bakenhaster et Fajer-Ávila, 2014 (males and females) from the ovary and testes of Lutjanus synagris (Linnaeus) (Lutjanidae); P. margolisi Moravec, Vidal-Martínez et Aguirre-Macedo, 1995 (male) from the ovary of Hyporthodus nigritus (Holbrook) (Serranidae) (new host record; probably a paradefinitive host); P. andersoni sp. n. (male) from the ovary of H. nigritus; Philometra sp. 1 (male) from the ovary of Rhomboplites aurorubens (Cuvier) (Lutjanidae); and Philometra sp. 2 (females) from the subcutaneous tissue of the anterior-most head sinuses of Hyporthodus niveatus (Valenciennes) (Serranidae). Specimens of species are described and illustrated based on light and (except for Philometra sp. 1) scanning electron microscopical examinations. Philometra haemulontis sp. n. differs from all congeners in the unique structure of the gubernaculum, whereas P. andersoni sp. n. can be differentiated from other gonad-infecting congeners parasitising the Serranidae by a combination of morphological features. Females of P. synagridis are described for the first time. Gravid females of Philometra sp. 2 are similar to those of P. morii Moravec, Bakenhaster et Fajer-Ávila, 2010, a subcutaneous parasite of Epinephelus morio (Valenciennes) (Serranidae) in the Gulf of Mexico.
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.
The nematode parasite Huffmanela huffmani Moravec, 1987 (Trichosomoididae) infects swimbladders of fishes in the family Centrarchidae. Only fish collected from the upper San Marcos River (Texas) have been found infected with H. huffmani eggs with a prevalence of 90%. Hundreds of thousands of H. huffmani eggs have been observed in these fish but only a few specimens of adult worms have ever been found. The San Marcos River arises from springs along the Balcones Fault Zone in San Marcos, Hays County, Texas. The restriction of the parasite to the upper San Marcos River and the high prevalence of the parasite eggs in centrarchids would seem to enable one to solve the life cycle of H. huffmani but this has proved false. Here, the insights and experiments used to help define some of the aspects concerning the life cycle of this enigmatic parasite are described. This study of H. huffmani includes a description of the habitat, the known limits of geographic distribution of the parasite, possible dispersal processes, egg characteristics, the testing of a possible intermediate host, Palaemonetes antrorum (Benedict) (Decapoda: Palaemonidae), and the effects of the digestion process on H. huffmani eggs.
In the years 1999-2002, first studies were carried out on the metazoan parasites of Atlantic salmon (Salmo salar L.) recently reintroduced into the Elbe River drainage system, after more than 50 years after the complete extinction of the Elbe salmon population. A total of six helminth species were recorded from salmon smolts from three streams of the Elbe River basin (Kamenice River, Ještědský and Libočanský Brooks) in North Bohemia, Czech Republic, where S. salar fingerlings have been released since 1998: Gyrodactylus truttae Gläser, 1974, Crepidostomum metoecus Braun, 1900, Diplostomum spathaceum (Rudolphi, 1819) metacercariae, Raphidascaris acus (Bloch, 1799) adults and encapsulated larvae, Cystidicoloides ephemeridarum (Linstow, 1872), and Neoechinorhynchus rutili (Müller, 1780). Except for D. spathaceum, all these freshwater parasites have been received from the helminth fauna of the co-habiting brown trout (Salmo trutta fario L.). Due to local ecological conditions, the parasite faunae of both salmon and brown trout exhibited distinct qualitative and quantitative differences in the three localities. The finding of G. truttae on S. salar represents a new host record. Three helminth parasites of marine origin, the cestodes Eubothrium crassum (Bloch, 1779) and Scolex pleuronectis Müller, 1788 plerocercoids, and the nematode Anisakis simplex (Rudolphi, 1809) larvae were found in the single examined adult S. salar from the Kamenice River. New data on the geographical distribution of some nematode parasites of Salmo trutta fario L., Barbatula barbatula (L.) and Anguilla anguilla (L.) are presented.
Based on light and scanning electron microscopical studies, the following nine species of Philometridae (Nematoda: Dracunculoidea) are described from female worms parasitizing marine perciform fishes belonging to six families off the northern coast Australia (near Darwin): Philometra australiensis sp. n. from the swimbladder of the king threadfin Polydactylus macrochir (Günther) (Polynemidae); P. epinepheli Dewi et Palm, 2013 from the operculum of the orange-spotted grouper Epinephelus coioides (Hamilton) (Serranidae); Philometra johnii Moravec et Ali, 2013 from the gonad of the croaker Johnius sp. (Sciaenidae); P. macrochiri sp. n. from the sensory fin of P. macrochir; P. zabidii sp. n. from the ovary of the ninespine batfish Zabidius novemaculeatus (McCulloch) (Ephippidae); Philometra sp. 1 and Philometra sp. 2 from the ovary of the Spanish flag snapper Lutjanus carponotatus (Richardson) (Lutjanidae) and the silver grunt Pomadasys argenteus (Forsskål) (Haemulidae), respectively; Philometroides eleutheronemae Moravec et Manoharan, 2013 from the ovary of the fourfinger threadfin Eleutheronema tetradactylum (Shaw) (Polynemidae); and Spirophilometra endangae Dewi et Palm, 2013 from the pectoral fins of E. coioides. The new species P. australiensis is characterized mainly by the structure of the cephalic end, 14 minute cephalic papillae, absence of caudal projections and body length of gravid female (67 mm), P. macrochiri by the presence of a conspicuously large anterior oesophageal bulb, 14 very small cephalic papillae and the truncated posterior end of body without any caudal projections, whereas P. zabidii is characterized by the presence of distinct caudal projections, the number (14) and larger size and arrangement of cephalic papillae, a poorly developed anterior oesophageal inflation, the body length (114 mm) and the host family (Ephippidae). All above-mentioned species were recorded from Australian waters for the first time.
The following three species of the Philometridae (Nematoda: Dracunculoidea) are described from marine perciform fishes of the Everglades National Park (northern Gulf of Mexico), Florida, USA: Philometra brevispicula sp. n. (male and females) from the subcutaneous tissue of mouth of the gray snapper Lutjanus griseus (Linnaeus) (Lutjanidae), Philometroides grandipapillatus sp. n. (only females) from pectoral fin muscle of the crevalle jack Caranx hippos (Linnaeus) (Carangidae), and Caranginema americanum Moravec, Montoya-Mendoza et Salgado-Maldonado, 2008 (females) from the subcutaneous fascia of trunk muscle in crevalle jack C. hippos. Philometra brevispicula is mainly characterized by small cephalic papillae of the external circle, the absence of oesophageal teeth and the presence of small caudal projections in gravid female, markedly short spicules (45 µm) in male, and by its location in the host. Philometroides grandipapillatus differs from congeners mainly in the shape of the cephalic region (narrow, conspicuously protruding), large cephalic papillae of the external circle and the absence of caudal projections in female, and by the site of infection in the host. Caranginema americanum is for the first time recorded from the northern Gulf of Mexico.
The following four species (only females available) of the Philometridae (Nematoda: Dracunculoidea) were recorded from freshwater fishes of Lake Turkana, northwestern Kenya in 2007-2008: Philometra bagri (Khalil, 1965) from the subcutaneous tissue around the mouth, on gill covers and the fin base of the bayad Bagrus bajad (Forsskål) (Bagridae: Siluriformes), Philometra lati sp. n. from the abdominal cavity of the Nile perch Lates niloticus (Linnaeus) (Latidae: Perciformes), Philometra spiriformis sp. n. from capsules on the inner surface of gill covers of L. niloticus and Afrophilometra hydrocyoni (Fahmy, Mandour et El-Nafar, 1976) comb. n. from the fins of Hydrocynus forskahlii (Cuvier) (Alestidae: Characiformes). The new species P. lati is characterized mainly by the presence of distinct oesophageal teeth, absence of large cephalic lobes and caudal projections, and by a combination of other features. Philometra spiriformis differs from all congeners principally in the spirally coiled body and from individual species by a combination of other morphological features. The already known species P. bagri and A. hydrocyoni are redescribed based on light and scanning electron microscopy; findings of both these species in Kenya represent new geographical records.
A new species of philometrid nematode, Philometroides africanus sp. n., is described from female specimens found encapsulated in gill arches and inner surface of gill covers of the African pike, Hepsetus odoe (Bloch), an endemic freshwater fish in Africa, from the Okavango River and Delta in Botswana. This new nematode is characterised mainly by a markedly small and plump body of gravid females (body length 6-9 mm), a separate anterior oesophageal bulb, a conspicuously small oesophageal gland, presence of four pairs of very small submedian cephalic papillae, and absence of any caudal processes. The prevalence of P. africanus in African pike of the Okavango Delta was 29%, with the intensity 1-8 (mean 3) encapsulated nematodes per fish. The genus Margolisianum Blaylock et Overstreet, 1999 is considered a junior synonym of Philometroides Yamaguti, 1935 and, consequently, its type species is transferred to the latter as Philometroides bulbosus (Blaylock et Overstreet, 1999) comb. n.