A new nematode species, Guyanema longispiculum sp. n. is described from the abdominal cavity of the freshwater armoured catfish, Loricariichthys hrunneus (Hancock), from two localities in western Venezuela. It differs from all hitherto known members of the genus in having unusually long spicules (0.480-0.609 mm) and from individual species also by other morphological and biometrical features. It is characterized by the presence of eight cephalic papillae arranged in two circlets, localization of deirids anterior to the nerve ring, a conical, undivided tip of the tail in both sexes, four pairs of preanal and six pairs of postanal papillae in the male, and a markedly elevated vulva in the female. A key to species of Guyanema is presented.
A new nematode genus and species, Lucionema balatonense gen. et sp. п., is described from the swimbladder of the European pikeperch, Stizostedion lucioperca (L.), from Lake Balaton in Hungary; a new dracunculoid family Lucionematidae fam. n. is established to accommodate it. The hitherto monotypie family Lucionematidae shows affinities with the families Skrja-billanidae and Daniconematidae, differing from them mainly in having simple oesophagus without external oesophageal glands and the vulva situated near the middle of body; from the first family also in the absence of the buccal capsule and the bursa-like caudal alae in the male. The genus Lucionema gen. n. is characterized mainly by the presence of 8 cephalic papillae in two circlets, absence of spicules, presence of the copulatory plate, only 2 pairs of postanal papillae in the male, and by the distal part of the monodelphic uterus forming a posteriorly directed coil. The body length of L. balatonense females is 1074-1782 pm, that of the only available male 770 pm. A key to the families of the Dracunculoidea is presented.
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.
Dracunculus globocephalus Mackin, 1927 (Nematoda: Dracunculoidea) is redescribed from specimens collected from the mesentery of the snapping turtle, Chelydra serpentina (L.), in Louisiana, USA. The use of scanning electron microscopy, applied for the first time in this species, made it possible to study details in the structure of the cephalic end and the arrangement of male caudal papillae that are difficult to observe under the light microscope. This species markedly differs from all other species of Dracunculus in having the spicules greatly unequal in size and shape, in the absence of a gubernaculum, and in the disposition of male caudal papillae. The validity of D. globocephalus is confirmed, but the above mentioned morphological differences are not sufficient for listing it in a separate genus. This is the first record of D. globocephalus in Louisiana.