New nematode species, Orientatractis mekongensis n. sp. (Atractidae) and Neosynodontisia suratthaniensis n. g., n. sp. (Pharyngodonidae) from freshwater fishes in Thailand

A new species of Orientatractis (Nematoda: Cosmocercoidea: Atractidae) parasite of Yellow-Spotted Amazon River Turtle, Podocnemis unifilis Troschel, 1848 (Testudines: Podocnemididae) in Brazilian Amazon

The current study describes a new species of nematode, Orientatractis matosi n. sp. (Atractidae), from the stomach and large intestine of Podocnemis unifilis Troschel, 1848 (Testudinidae), collected in the Tocantins and Xingu rivers in the Brazilian state of Pará. The new species was described using light and scanning electron microscopy and differs from its congeners mainly in the number and distribution of the male caudal papillae and by having a shorter right spicule. Orientatracits matosi n. sp. is the eleventh species of the genus Orientatractis Petter, 1966, the third reported from the Amazon, and the second described from P. unifilis.

A new species of Orientatractis (Nematoda: Atractidae) from the tortoise Indotestudo elongata (Blyth) in China

A new species of nematode, Orientatractis longicaudata n. sp. is described from the intestine of Indotestudo elongata (Blyth) (Testudinidae) from Zoo of Tianjin, Tianjin, China. The new species can be easily distinguished from its congers by having longer tail, by the length of gubernaculum and left spicule, and by the numbers of caudal papillae. This is first species of Orientatractis Petter, 1966 reported in China. A key to the species of Orientatractis is provided.

Two nematode species from freshwater and marine fishes in Thailand, including Ascarophis scatophagi sp. nov. (Cystidicolidae) from Scatophagus argus (Scatophagidae)

One new and one known species of parasitic nematodes are reported from Thailand for the first time: Falcaustra kaverii (Karve et Naik,1951) (Kathlaniidae) from the intestine of the freshwater fish Poropuntius deauratus (Valenciennes) (Cyprinidae) (new host record) and Ascarophis scatophagi sp. nov. (Cystidicolidae) from the intestine of the marine fish Scatophagus argus (Linnaeus) (Scatophagidae). The morphology of both these species was studied with the use of light (LM) and scanning electron microscopy (SEM) (the latter method used for F. kaverii for the first time). The new species (A. scatophagi) is mainly characterized by nonfilamented, markedly elongate-oval eggs (size 42-45 × 18 μm), spicules 555-642 μm and 105-150 μm long, the muscular/glandular oesophagus length ratio (1:13-34), bifurcate deirids, the length of the female tail (159-249 μm) and cephalic structures typical of the nominotypical subgenus Ascarophis. Representatives of Falcaustra Lane, 1915 and Ascarophis van Beneden, 1871 were not previously reported from fishes in Thai waters.

Orientatractis moraveci n. sp. and Rondonia rondoni Travassos, 1920 (Nematoda: Atractidae), parasites of Pimelodus blochii (Osteichthyes, Pimelodidae) from the Acre and Xapuri Rivers, Western Amazon, Brazil

The fish fauna in the State of Acre represents 10·7% of all fish species recorded from Brazil, but, despite this, there are few fish parasite studies in this area. The recent expansion of fish farming in Acre prompted a need for helminthological studies of the most commonly consumed fish species in the area, Pimelodus blochii (Pimelodidae). The aim of this study was to analyse the helminth fauna of P. blochii from the Acre and Xapuri Rivers in Northwestern Brazil. Numerous nematodes were collected from the intestine and two species of the family Atractidae were identified: Rondonia rondoni Travassos, 1920 and Orientatractis moraveci n. sp. The new species is distinguished from its congeners mainly by having: 10 pairs of caudal papillae (3 pairs pre-cloacal, 2 pairs ad-cloacal and 5 pairs post-cloacal); unequal spicules of 161-198 and 69-100 µ m long; and a gubernaculum 38-58 µ m long with an antero-lateral process. Morphological and ultrastructural data on O. moraveci n. sp. and R. rondoni are presented, in addition to new genetic data based on partial 18S rDNA and 28S rDNA. The taxonomic status of Labeonema synodontisi (Vassiliadès, 1973) is discussed, suggesting that it should be returned to the genus Raillietnema.