Redescription of Parspina argentinensis (Szidat, 1954) (Digenea: Cryptogonimidae) from freshwater fishes (Pimelodidae) in the basins of the Paraná and La Plata Rivers, Argentina, with comments on P. bagre Pearse, 1920

Abstract

The type-specimens of Parspina argentinensis (Szidat, 1954) from Pimelodus maculatus Lacépède, and new material from Iheringichthys labrosus (Lütken), Parapimelodus valenciennis (Lütken), Pimelodella gracilis (Valenciennes), Pimelodus albicans (Valenciennes), P. argenteus Perugia and P. maculatus caught in the basins of the La Plata and Paraná Rivers, Argentina, were studied to elucidate its taxonomic status. The type-specimens of Parspina bagre Pearse, 1920 from Pimelodella metae Eigenmann in Lake Valencia, Venezuela, were also studied and new observations on its morphology recorded. The amendation of the generic diagnosis of Parspina Pearse, 1920 is proposed based on the study of both species, which revealed, among other features, the absence of a thin walled-membrane enclosing the male terminal genitalia. Parspina argentinensis is characterised by the following features: absence of a gonotyl; presence of a bipartite seminal vesicle, pars prostatica and ejaculatory duct; caeca of nearly equal length; uterus extending from the level of the ventral sucker to end of body; testes symmetrical to slightly oblique; ovary transversely elongate, compact and variable in shape; and the utilisation of a wide range of freshwater fishes as hosts. The tegumental surface of this species is covered with pectinate spines arranged quincuncially. Spines decrease in size and density from forebody to hindbody. There are two types of sensory papillae, ciliated and dome-shaped. Ciliated papillae are distributed on the surface of the oral region and on the dorsal and ventral surfaces of the body, whereas dome-shaped papillae are found on the surface of the ventral rim of the oral sucker associated with a ciliated papilla. Gland-duct openings are interspersed with the spines of the oral crown. In addition, the infection indices of P. argentinensis vary widely, not only among different hosts but also between the Paraná and La Plata River basins. Higher prevalences of P. argentinensis are recorded in the La Plata River, and Pimelodus albicans, P. maculatus and Iheringichthys labrosus are the principal final hosts in this area.

Topography and ultrastructure of the tegument of Aphallus tubarium (Rodolphi, 1819) Poche, 1926 (Digenea: Cryptogonimidae), intestinal parasite of the common Dentex dentex (Linnaeus 1758) from Valinco Gulf

“…The posterior spine measurements of our material are clearly smaller than those from the rest of body. Our results contrast also with those reported for the P. (Stossich, 1883), there are absent at the posterior tip of body (Bartoli and Gibson, 2001;Ostrowski de Nũnez et al, 2011). The number of digitations differs from other digenean species according parts of body.…”

“…Sensory receptors are common and varied among digeneans. They have been observed singly or grouped, bearing short or long cilia or devoid of cilia (Cohen et al, 1995;Han et al, 2003;Ostrowski de Nũnez et al, 2011). Our results highlighted 2 types of sensory structures already identified in other Cryptogonimidae species such as Parspina argentinensis Szidat 1954 or Metadena phoceae Bartoli and Gibson 2001.…”

“…Some digenean species such as Diplostomum pseudospathaecum Niewiadomska, 1984 or Prosorhynchoides arcuatus (Linton, 1900) Bray, 1984 posses a conical dense structure and rootlets on basal body of cilium not observed on A. tubarium (Cohen et al, 1995;Czubaj and Niewiadomska, 1996). Our study revealed also a difference in mean cilia lengths between A. tubarium and other species (Ostrowski de Nũnez et al, 2011). Bennett (1975) mentioned that the cilium might be capable to recording the direction and degree of any pressure acting on spines, as they are protruding to the same height as the surrounding spines.…”

“…In A. tubarium, these structures differ from other Cryptogonimidae species in size, shape, number of digitations and distribution on the body surface (Bartoli and Gibson, 2001;Tkach and Snyder, 2003;Ostrowski de Nũnez et al, 2011). Examples include Metadena depressa (Stossich, 1883), Metadena phoceae Gibson 2001, Parspina argentinensis (Szidat, 1954) or Parspina bagre Pearse, 1920 (Bartoli andGibson, 2001;Ostrowski de Nũnez et al, 2011).…”

“…Examples include Metadena depressa (Stossich, 1883), Metadena phoceae Gibson 2001, Parspina argentinensis (Szidat, 1954) or Parspina bagre Pearse, 1920 (Bartoli andGibson, 2001;Ostrowski de Nũnez et al, 2011). The pattern of digenean tegumental spines is a commonly quoted taxonomic feature, and differences in structures and distribution over the body may be significant in host parasites relationship (Bundy, 1982;Chai et al, 2000).…”