A new nematode species, Atractis vidali sp. n., is described from the intestine of cichlid fishes, Vieja intermedia (Günther) (type host) and Cichlasoma pearsei (Hubbs), from specimens collected in three localities in the Mexican states of Campeche (Santa Gertrudis Creek) and Chiapas (Cedros and Lacanjá Rivers). It differs from the only other atractid species reported in fishes of Mexico, Atractis bravoae, mainly in possessing two very unequal spicules. In contrast to the 10 species parasitising amphibians and reptiles in America, the new species has a longer body, spicules and a gubernaculum, and a different distribution of the caudal papillae. This is the second species of the genus Atractis recorded from freshwater fishes.
A new nematode species, Spirophilometra pacifica sp. n. (Philometridae), is described from gravid female specimens collected from the mouth cavity (the upper palate) of the fish (yellow snook) Centropomus robalito (Centropomidae, Perciformes) from the Chantuto-Panzacola system, Chiapas, in the Pacific coast of Mexico. Its morphology is very similar to that of the species originally described as Philometra centropomi Caballero, 1974, but the gravid females of S. pacifica are about three times longer (body length 11.63-18.17 mm); host species and the geographical distribution of both these forms also differ. Scanning electron microscope (SEM) examination of S. pacifica, used for the first time for a Spirophilometra species, confirmed the presence of numerous minute cuticular spines on the body surface, 14 cephalic papillae arranged in two circlets, and two small lateral papilla-like caudal projections. It is evident that some features of P. centropomi were incorrectly described (its types are not available) and this species is now transferred to Spirophilometra as S. centropomi (Caballero, 1974) comb. n.
A pathogenic Asian nematode species of Camallanus, C. cotti Fujita, 1927, was found in New Caledonia, South Pacific, for the first time; it was recorded from two native fishes, Awaous guamensis (Valenciennes) (Gobiidae) (prevalence 51%, intensity 1-25) and Kuhlia marginata (Cuvier) (Kuhliidae) (a single specimen found), of the La Foa River, about 100 km north of Nouméa; the latter represents a new host record. Morphological data on C. cotti based on New Caledonian specimens and those previously collected from aquarium-kept Misgurnus anguillicaudatus (Cantor) in Canada have been provided. The SEM examination of C. cotti, applied for the first time in this species, made it possible to study some of its morphological details; first-stage larvae from the female's uterus were found to possess several digit-like processes on the tail tip, not previously reported for any species of the Camallanidae. Camallanus moraveci Petter, Cassone et France, 1974 is considered a junior synonym of C. cotti. A list of hitherto recorded hosts of C. cotti is provided. Camallanus cotti is assumed to be introduced into New Caledonia along with the introduction of the exotic poeciliid fishes, which are known to be among the most common hosts of C. cotti in aquarium cultures worldwide.
Two species of the genus Baruscapillaria Moravec, 1982 are known to parasitise the small intestine of the common cormorant, Phalacrocorax carbo (L.): Baruscapillaria carbonis (Dubinin et Dubinina, 1940) and B. rudolphii Moravec, Scholz et Našincová, 1994. A redescription of the former species, based on specimens collected from common cormorants shot in South Bohemia, Czech Republic, is provided. Morphological features distinguishing B. carbonis and B. rudolphii are specified. B. carbonis is characterised mainly by the well-developed membranous bursa in the male, composed of five distinct lobes (four lateral and one spur-shaped dorsal); the length of the spicule is 1.9-2.3 mm; gravid females are provided with a long vulvar appendage. Males of B. rudolphii have reduced, bi-lobed membranous bursa and the spicule is 0.9-1.3 mm long; the vulvar appendage is absent in gravid females. This is the first record of B. carbonis in the Czech Republic.
A new species of parasitic nematode, Cucullanus oceaniensis sp. n., is described from the intestine of the giant mottled eel Anguilla marmorata (type host) from Futuna Island (Wallis and Futuna Islands, Polynesia) and from A. marmorata and Anguilla sp. (cf. obscura) from Fiji Islands (Melanesia, South Pacific). The main distinguishing characteristics are the length of spicules (668-1,020 µm), situation of deirids (slightly anterior to the oesophago-intestinal junction) and the excretory pore (some distance posterior to the end of oesophagus), and the arrangement of caudal papillae in the male. It is the third known species of Cucullanus from Oceania and the first one reported from freshwater eels in the region of South Pacific. Cucullanus faliexae Morand et Rigby, 1998 is considered a junior synonym of Cucullanus australiensis Baylis, 1927.
A new nematode species, Cucullanus pargi sp. n., is described from the intestine and pyloric caeca of the grey snapper, Lutjanus griseus (Linnaeus), off the southern Quintana Roo coast, Mexico. This species shows similar morphological features as cucullanids occurring in marine and brackish-water fishes; however, it differs from all other species in the length of spicules, arrangement and number of caudal papillae, position of the excretory pore and deirids. Cucullanus pargi is the third species of this genus described from fishes in Mexico and the second one from Mexican marine fishes.
Examinations of nematodes collected from some marine fishes off the southwestern coast of Java, Indonesia in 2000 and 2001 revealed the presence of the following six species: ascaridoids Ichthyascaris grandis sp. n. from the intestine of Lophiomus setigerus (Vahl), I. cf. longispicula Li, Liu, Liu et Zhang, 2012 from the intestine of Conger cinereus Rüppel, Ichthyascaris sp. from the body cavity of Lobotes surinamensis (Bloch), and Raphidascaroides halieutaeae Yin, 1983 from the intestine of Halieutaea stellata (Vahl), and philometrids Philometra ivaschkini Parukhin, 1976 from the stomach wall of Trichiurus lepturus Linnaeus and P. psettoditis Moravec, Walter et Yuniar, 2012 from the body cavity (liver) of Psettodes erumei (Bloch et Schneider). Descriptions of these nematodes based on light and scanning electron microscopical studies are provided. The new species I. grandis sp. n. is mainly characterised by large body measurements (males and females up to 41.8 mm and 73.6 mm long, respectively), the length of spicules (0.99-1.05 mm), the tail tip usually without rudimentary spines and by the presence of 44-53 pairs of caudal papillae, eight to twelve of which being postanals. In addition to new data on the morphology of R. halieutaeae and other nematodes recorded, the 11 species of Raphidascaroides Yamaguti, 1941 poorly described from marine fishes in South Asia and reviewed in the monograph of Sood (2017) are considered species inquirendae and incertae sedis.
A new nematode species, Rhabdochona (Globochona) rasborae sp. n. (Rhabdochonidae), is described from the intestine of the freshwater cyprinid fish (sidestripe rasbora) Rasbora paviana Tirant in the Bangbaimai Subdistrict, Muang District, Surat Thani Province, southern Thailand. It differs from other representatives of the subgenus Globochona Moravec, 1972 which possess eggs provided with lateral swellings in having a spinose formation at the tail tip of both sexes and in some other morphological features, such as the body length of gravid female (8.6-23.7 mm), presence of two-three swellings on the egg, eight anterior prostomal teeth, length ratio of spicules (1 : 5.3-6.7) and arrangement of male genital papillae. This is the third nominal species of Rhabdochona Railliet, 1916 and the second species of the subgenus Globochona reported from fishes in Thailand. The three species of Rhabdochona recently described from fishes in Pakistan, viz. R. annai Kakar, Bilqees et Khan, 2012, R. bifurcatum [sic] Kakar et Bilqees, 2012, and R. pakistanica Kakar, Bilqees et Khan, 2012, are considered to be species inquirendae.
The larval development of the nematode Contracaecum rudolphii (Rudolphi, 1819), a common parasite of the proventriculus of cormorants, was experimentally studied. Within the eggs cultivated in freshwater under laboratory temperatures of 20-22 °C, the developing larva undergoes two moults on days 4-5, attaining the third larval stage. Most of the ensheathed third-stage larvae, 291-457 µm long, hatch spontaneously from egg shells on days 5-6. Experiments have indicated that hatched ensheated third-stage larvae and those still inside egg capsules are already infective to copepods and fishes, which both can be considered paratenic (metaparatenic) hosts. Five copepod species, Acanthocyclops vernalis, Cyclops strenuus, Ectocyclops phaleratus, Eucyclops serrulatus and Megacyclops viridis, the isopod Asellus aquaticus and small carps Cyprinus carpio were infected by feeding them these larvae. In addition, 9 fish species, Alburnoides bipunctatus, Anguilla anguilla, Barbatula barbatula, Cyprinus carpio, Gobio gobio, Perca fluviatilis, Phoxinus phoxinus, Poecilia reticulata and Tinca tinca, were successfully infected by feeding them copepods previously infected with C. rudolphii third-stage larvae. In fishes, larvae from copepods penetrate through the intestinal wall to the body cavity, where, in a few weeks, they become encapsulated; the larvae substantially grow in fish, attaining the body length up to 4.87 mm. In carp fry, the nematode third-stage larvae survived for about 15 months (up to 18 months in fish infected directly, i.e., without copepods). One small cormorant (Phalacrocorax carbo sinensis) was successfully infected by feeding it with copepods harbouring C. rudolphii third-stage larvae.
The nematode Goezia spinulosa (Diesing, 1839) (Raphidascarididae) is redescribed based on specimens found in the stomach and intestine of the naturally infected arapaima Arapaima gigas (Schinz) from the Mexiana Island, Amazon River Delta, Brazil. Light and electron microscopy examinations revealed some previously unreported or inaccurately described morphological features in the species, such as the position of the excretory pore, phasmids in the male or the number (4) of postanal papillae. The morphology of G. spinulosa is compared with that of other four congeneric species parasitizing freshwater fishes in South America. This nematode seems to be one of the most pathogenic parasites of A. gigas in the Mexiana Island, which are responsible for a high mortality of cultured arapaima fingerlings. Apparently, the source of G. spinulosa infection for arapaima fingerlings cultured in tanks was the infected plankton collected in the localities inhabited by wild arapaimas. Therefore, control measures should include the sterilisation of the plankton before its use as food for fish. A rare infection of Eustrongylides sp. larvae (Dioctophymatidae) in arapaima fingerlings was also found (new host record); the larvae were inside swellings on the body surface.