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.
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 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.
During a survey of freshwater fishes from Turkey two species of Acanthocephala, one of them new, were found. Pomphorhynchus tereticollis (Pomphorhynchidae) is reported at 24% prevalence in 37 Cobitis bilseli (Cobitidae) from Lake Beysehir, Konya, for the first time. The eoacanthoacaphalan Triaspiron aphanii gen. n. et sp. n. (Quadrigyridae), at a prevalence of 90%, is described from 29 Aphanius mento (Cyprinodontidae), from Kirkgöz Springs, Antalya. The new genus most closely resembles Raosentis Datta, 1947, both having a small spindle shaped trunk, and Acanthogyrus Thapar, 1927, both having a proboscis armature of three circles of hooks. Triaspiron differs from Raosentis in proboscis shape, cylindrical not globular, proboscis armature, three circles, a total of 16 hooks in all, not four circles, a total of 26-30 hooks in all, and trunk spination, two fields of spines in the anterior field with spines arranged in up to 40 circular rows, not a single field with 9-17 rows of spines. Triaspiron differs from Acanthogyrus in having fewer proboscis hooks, 16 compared with 18-24, arranged in three circles, one anterior and two posteriorly placed, with an unarmed region between, not three circles of hooks evenly spaced, and two fields of trunk spines, not one.
Monozoic cestodes of the genus Khawia Hsü, 1935 (Caryophyllidea: Lytocestidae), parasites of cyprinid fish in Europe, Asia, Africa and North America, are revised on the basis of taxonomic evaluation of extensive materials, including recently collected specimens of most species. This evaluation has made it possible to critically assess the validity of all 17 nominal species of the genus and to provide redescriptions of the following seven species considered to be valid: Khawia sinensis Hsü, 1935 (type species); K. armeniaca (Cholodkovsky, 1915); K. baltica Szidat, 1941; K. japonensis (Yamaguti, 1934); K. parva (Zmeev, 1936); K. rossittensis (Szidat, 1937); and K. saurogobii Xi, Oros, Wang, Wu, Gao et Nie, 2009. Several new synonyms are proposed: Khawia barbi Rahemo et Mohammad, 2002 and K. lutei Al-Kalak et Rahemo, 2003 are synonymized with K. armeniaca; K. coregoni Kritscher, 1990 with Caryophyllaeus laticeps (Pallas, 1781) (family Caryophyllaeidae); K. cyprini Li, 1964 and K. iowensis Calentine et Ulmer, 1961 with K. japonensis; K. dubia (Szidat, 1937) (syn. Bothrioscolex dubius Szidat, 1937) with K. rossittensis; and Tsengia neimongkuensis Li, 1964 and T. xiamenensis Liu, Yang et Lin, 1995 with K. sinensis. Khawia prussica (Szidat, 1937) (syn. Bothrioscolex prussicus Szidat, 1937) is considered to be species incertae sedis, but its morphology indicates it may belong to Caryophyllaeus Gmelin, 1790 (Caryophyllaeidae). The molecular analysis of all seven valid species, based on comparison of sequences of two nuclear ribosomal and two mitochondrial genes, has shown that the species form three major groups clustered according to their fish hosts. Five species from common and crucian carp and goldfish were grouped together, whereas K. armeniaca from barbels (Barbinae) and K. baltica from tench (Tinca) formed separate clades. In contrast, geographical distribution does not seem to play a crucial role in grouping of individual taxa. A phylogenetic tree based on morphological characters was incongruent with that inferred from molecular data, which indicates that some morphological traits may be homoplastic. A key to identification of all species of Khawia based on morphological characteristics is provided.
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).
Based on light and scanning electron microscopical studies, three new, one already known and one not identified species of the nematode genus Rhabdochona Railliet, 1916 are reported from the intestine of freshwater fishes in Dzanga-Sangha Protected Areas (Congo River basin), the Central African Republic: Rhabdochona (Rhabdochona) centroafricana sp. n. from Barbus miolepis Boulenger, R. (R.) marcusenii sp. n. from Marcusenius greshoffii (Schilthuis), R. (Globochona) paski Baylis, 1928 from Phenacogrammus aurantiacus (Pellegrin) (new host record), R. (G.) tricuspidata sp. n. from Raiamas christyi (Boulenger) and Rhabdochona (G.) sp. (only females) from Epiplatys multifasciatus (Boulenger). Rhabdochona centroafricana is mainly characterised by the length of the left spicule (333 µm) and the presence of the operculum bearing a conspicuous gelatinous formation on one of egg poles, R. marcusenii by the length of the left spicule (453-486 µm) and the presence of a single broad filament on one egg pole only and R. tricuspidata by the body with marked cuticular ornamentations and deirids branching into three prongs. A key to valid species of Rhabdochona parasitic in fishes of Africa is provided.
A new genus, Ritacestus, is proposed to accommodate Ritacestus ritaii (Verma, 1926) comb. n. (syn. Proteocephalus ritaii), a parasite of the catfish Rita rita (Hamilton) in India. The new genus, which is placed in the Gangesiinae, is characterized by (i) a small, subspherical scolex formed by four large lobes separated from one another by longitudinal grooves, with a large, widely oval to pyriform rostellum-like apical organ, larger than suckers and possessing an apical hemispherical depression; (ii) paramuscular and cortical position of some vitelline follicles (most follicles are situated medullary); (iii) ventral and dorsal bands of vitelline follicles usually uninterrupted ventral to terminal genitalia and reaching to the posterior margin of proglottides; (iv) the vagina always anterior to the cirrus-sac; (v) a large size of the body (length up to 51 cm); and (vi) development of the uterus of type 2. In its morphology, especially shape of the scolex and apical organ, and paramuscular and cortical position of some vitelline follicles, Ritacestus resembles Postgangesia Akhmerov, 1969, but differs in the presence of a genital atrium (both genital pores of Postgangesia are separate), the anterior position of the vagina (almost always posterior in the latter genus), position of vitelline follicles in cross sections (dorsal and ventral bands in Ritacestus versus only a lateral band in the latter genus), and dorsal excretory canals indistinguishable in mature and gravid proglottides of R. ritaii (well developed in Postgangesia spp.). The type and only species of the genus, R. ritaii, is redescribed on the basis of new material from the type host from the Ganges River basin in India and its neotype is designated.
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.
In Cobitis taenia and, with lower intensity, also in C. elongatoides and C. melanoleuca, females bear visible spawning marks on the body sides after spawning events. These marks intensify during the spawning season but disappear a few weeks after the last spawning event. The precise origin of the spawning marks is not clear, but they seem to be produced by the male during embracement of the female. Spawning marks were not observed after spawning events of C. bilineata, C. fahirae, C. rara, C. paludica, C. strumicae and C. turcica. An example dataset from Haaren creek in northwestern Germany is given to demonstrate that these marks can be used as a tool to precisely estimate the start of reproductive season for Cobitis populations, separately even for different size classes.