Endoparasites of Steindachinerina brevipinna ( Eigenmann and Eigenmann , 1889 ) , collected in the tributaries Corvo and Guairacá of Paranapanema river , Paraná State , Brazil

Steindachnerina brevipinna is a freshwater fish from the Curimatidae family, and its occurrence is restricted to some South American countries (Argentina, Brazil, Paraguay and Uruguay), distributed in the Paraguay, lower and upper Paraná and lower Uruguay rivers. There are no parasitological studies related to this fish. The present study records and illustrates a species of digenean, Sphincterodiplostomum musculosum from subfamily Diplostominae, present on the ovary and three species of nematodes, Cosmoxynema vianai Travassos, 1949, Travnema travnema Pereira, 1938, Spinoxyuris sp., of superfamily Oxyuridea, parasitizing the intestine of S. brevipinna collected in the tributaries Guairacá and Corvo of the Paranapanema River, Parana State, Brazil.

Most nematodes of superfamily Oxyuridea Cobbold, 1864 are parasites of neotropical fishes of South America and only a few genera of family Pharyngodonidae occur in marine and freshwater fish of tropical and subtropical regions. There are seven genera known to the superfamily Oxyuridea in South America, with 11 species described (MORAVEC, 1998). The species belonging to the genus Brasilnema Moravec, Kohn and Fernandes, 1992, Cosmoxynema Travassos, 1949, Cosmoxynemoides Travassos, 1949, Ichthyouris Inglis, 1969, Parasynodontidia Moravec, Kohn and Fernandes, 1992, Travnema, Pereira, 1938, are registered to fishes from Brazil (PEREIRA, 1938;TRAVASSOS, 1949;FERNANDES et al., 1983;MORAVEC et al., 1992); two species of Parasynodontidia and Spinoxyuris Petter, 1994, of fishes from Paraguay (PETTER, 1994; and only one species of Ichthyouris from Guyana (INGLIS, 1962). One species of Diplostomidae and three species of Pharyngodonidae were found in Steindachnerina brevipinna (Eigenmann and Eigenmann, 1889), a freshwater fish of Curimatidae family, which is found in lakes, rivers and channels (GRAÇA; PAVANELLI, 2007). Therefore, due to their feeding habit as detritivores (FINK;FINK, 1978) There are no publications of parasitological studies related to this fish, but only records of endoparasites of the genus Diplostomum sp. for Steindachnerina insculpta (PAVANELLI et al., 2004), an endemic species of the upper Paraná river (PAVANELLI; BRITSKI, 1999).
This manuscript reports and illustrates a digenean species of subfamily Diplostominae and two species and one genus of nematodes of superfamily Oxyuridea found in S. brevipinna collected in tributaries Guairacá and Corvo of the Paranapanema river.  Gills nets with different mesh sizes were used for capturing the fish, disposed for a period of 24 hours, with collections every eight hours. Parasites were collected and processed according to Eiras et al. (2006) The measurements were standardized in millimeters and the illustrations were made with the aid of a drawing tube attached to a Nikon YS 2 microscope. Representative specimens were deposited in the Helminthological Collection of the Oswaldo Cruz Institute, Rio de Janeiro, Rio de Janeiro State, Brazil.   et al., 2005) and Hemisorubim platyrhynchos to Sphincterodiplostomum sp. (GUIDELLI et al., 2003). Distribution Sphincterodiplostomum musculosum first described by Dubois (1936) in fishes of Neotropical region (NIEWIADOMSKA, 2002). Was found also in Guandu river, Rio de Janeiro State, Brazil (ABDALLAH et al., 2005), in Paraná river, Brazil, as Sphincterodiplostomum sp. (GUIDELLI et al., 2003) and their adult form in birds of Formosa Province, Argentina (LUNASCHI; DRAGO, 2006).

Comments
Quoy and Gaimard in 1824 described this species parasitizing the eyes of Cyphocharax gilbert. In S. brevipinna was found in large quantities in the ovaries, being the most prevalent endoparasite. The adult form was described by Lunaschi and Drago (2006), parasitizing the intestine of Ardea alba, Linneaus 1758.
The illustration shows clearly the body bipartite in forebody and hindbody. The anterior region has vitellaria concentrated, oral sucker, pseudosuckers, ventral suckers and tribocitic organ. In posterior region has one ovary, one pair of testes and one subterminal sphincter.    (1985) and Moravec et al. (1992) respectively.

Comments
The genus Cosmoxynema was described by Travassos in 1949, and has only one species (MORAVEC, 1998). Of all nematodes found in S. brevipinna, Cosmoxynema vianai showed most long. In most cases only two parasites were found in a single host, always female. There was no record for males.
According Moravec (1998), Travassos not find the male of the species. The same is true for genus Cosmoxynemoides, very similar to the Cosmoxynema.
The illustration shows in the anterior region, cuticle striated, oesophagus and nerve ring, eggs distributed only in one region of the body, ovary and muscular vagina; in posterior region and an abrupt decrease of diameter after anus, forming a thin and long tail.  Measures based on 15 female and one male specimens.
Male: body size two times smaller than the female, 1.130 long and 0.055 wide. Oesophagus, 0.125 long and 0.025 wide; divided in: anterior region of oesophagus, 0.055 long and 0,020 wide; Isthmus, 0.037 long and 0,013 wide; and Bulb, 0.009 long and 0.014 wide; Conical tail with sharp curvature, 0.118 long and 0.080 wide in anterior region and 0.010 near to end; One spicule, 0.047 long and wide base 0.007, gubernaculum absent.  (MORAVEC, 1998).

Comments
The genus Travnema was described by Pereira (1938) and has two species, T. araujoi and T. travnema. The main difference between them is the presence of denticles in the buccal capsule of the first species. Besides being one of the oldest genera of Superfamily Oxyuridea, with Laurotravassoxyuris described in same year by Vigueiras (MORAVEC, 1998), T. travnema had the highest distribution and prevalence of all parasites found in S. brevipinna.
This parasite is small and therefore difficult to visualize on stereoscopic microscope, being best viewed after viscera washing with sieve (154 μm).
The illustration shows in the anterior region of the parasite, transverse striations, buccal capsule, oesophagus and nerve ring, vulva located in posterior region of the second third of body, in posterior region of parasite can be observed, the final part of intestine and anus; egg in initial and final stage.   (MORAVEC, 1998).

Comments
The Spinoxyuris genus was described by Petter (1994) with records of both sexes for a single species, Spinoxyuris oxydoras in host Oxydoras kneri, collected in Paraná river, Alto Paraná Province, Paraguay (MORAVEC, 1998). This parasite species possibly belongs to a new species, but this single specimen limits the identification only to genus level.
The illustration shows in the anterior region of the parasite, one irregular bulb which probably obtained such features due to methods of fixation. In posterior region can be observed a developed genital cone, caudal alae and only a single spicule with grooves.