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New host records of Prosthenhystera obesaMartins et al.It is possible that the location of parasitism is acontrolling factor of parasitic intensity. Pavanelliet al. (1992) state that P. obesa is relatively large inrelation to the organ it parasitizes, and as theparasite uses bile of the gall bladder, an increase ofinfection intensity could be harmful for both thehost and the parasite. In this case, the gall bladdercould be a limiting factor for infrapopulationsobserved in this study, which varied from one to nomore than three specimens.It can be suggested that in case the parasites werenot recently acquired by the host, there isphylogenetic implication optimizing thedevelopment to maturity of P. obesa inCharaciformes and absence of such a relationshipbetween P. obesa and Siluriformes.In the present study, the list of known SouthAmerican hosts of P. obesa is enlarged byincluding the anostomid L. reinhardti and thepimelodid P. pohli of the São Francisco River,Brazil.ACKNOWLEDGEMENTSOur thanks to Yoshimi Sato, researcher atCIRPA/CODEVASF, Três Marias, MG, andCEMIG-GT/CODEVASF working arrangementfor providing logistical and material support; andto Dr. Philip J. Scholl for English revision. Claudiada Silveira São Sabas was supported by a studentfellowship from the Coordenação deAperfeiçoamento de Pessoal de Nível Superior(Capes-Brazil).BIBLIOGRAPHIC REFERENCESAlbuquerque, MC. 2009. Taxonomia e aspectosecológicos da fauna parasitária deTriportheus guentheri (Garman, 1890) eTetragonopterus chalceus Spix & Agassiz,1829 no Reservatório de Três Marias, AltoRio São Francisco, MG. Dissertação deMestrado em Ciências, UniversidadeFederal Rural do Rio de Janeiro,Seropédica.Amato, JFR, Boeger, WA & Amato, SB. 1991.Protocolos para laboratório: coleta eprocessamento de parasitos de pescado.Gráfica da Universidade Federal Rural doRio de Janeiro, Seropédica.Brasil-Sato, MC. 2002. Digenea of Salminusbrasiliensis (Cuvier, 1817) (Osteichthyes,Characidae) of the São Francisco riverbasin, Brazil. Revista Brasileira deParasitologia Veterinária, vol. 11, pp. 95-98.Brasil-Sato, MC. 2003. Parasitos de peixes dabacia do São Francisco. In: Godinho, HP& Godinho, AL. (eds.). Águas, peixes epescadores de São Francisco das MinasGerais. PUCMINAS, Belo Horizonte.Brasil-Sato, MC & Santos, MD. 2003. Helmintosde Myleus micans (Lütken,1875)Characiformes: Serrasalminae) do RioSão Francisco, Brasil. Revista Brasileirade Parasitologia Veterinária, vol. 12, pp.131-134.Brasil-Sato, MC & Santos, MD. 2005. Metazoanparasites of Conorhynchos conirostris(Valenciennes, 1840), an endemicsiluriform fish of the São Francisco basin,Brazil. Revista Brasileira de ParasitologiaVeterinária, vol. 14, pp. 160-166.Brasil-Sato, MC & Pavanelli, GC. 2004. Digeneade Pimelodus maculatus (Osteichthyes,Pimelodidae) das bacias dos rios SãoFrancisco e Paraná, Brasil. ParasitologiaLatinoamericana, vol. 59, pp.123-131.Bray, RA. 2002. Superfamily GymnophalloideaOdhner, 1905. In Gibson, DI, Jones, A &Bray, RA. (eds.). Keys to the Trematoda,vol.1. CABI Publishing and The NaturalHistory Museum, Wallingford.Britski, HA, Sato, Y & Rosa, ABS. 1988. Manualde identificação de peixes da região deTrês Marias (com chaves de identificaçãopara os peixes da Bacia do São Francisco).3°.ed., CODEVASF, Brasília.Bush, AO, Lafferty, JM & Shostak, AW. 1997.Parasitology meets ecology on its ownterms: Margolis et al. revisited. Journal of38