Digenean parasites of the Neotropic Cormorant , Phalacrocorax brasilianus ( Gmelin , 1789 ) ( Aves : Phalacrocoracidae ) from Argentina : Distribution extension and new host records

Thirteen specimens of Phalacrocorax brasilianus (Gmelin, 1789) from three areas of the Chaqueña Subregion of Argentina were examined for digeneans. Ten species were found: four diplostomids (Austrodiplostomum mordax, A. ostrowskiae, Tylodelphys adulta and Hysteromorpha triloba), three echinostomatids (Drepanocephalus spathans, Paryphostomum segregatum, and P. parvicephalum), one strigeid (Strigea falconis brasiliana), one psilostomid (Ribeiroia ondatrae) and one prosthogonimid (Prosthogonimus ovatus). Tylodelphys adulta and S. f. brasiliana are reported for the first time as parasites of P. brasilianus and new geographical records are presented. Museo de La Plata, Laboratorio de Helmintología. Paseo del Bosque S/No, 1900. La Plata, BA, Argentina. * Corresponding author. E-mail: fdrago@fcnym.unlp.edu.ar Fabiana Beatriz Drago *, Lía Inés Lunaschi and Maria Schenone Digenean parasites of the Neotropic Cormorant, Phalacrocorax brasilianus (Gmelin, 1789) (Aves: Phalacrocoracidae) from Argentina: Distribution extension and new host records Check List | Volume 7 | Issue 6 | 2011 Phalacrocorax brasilianus (Gmelin, 1789), commonly known as the Neotropic Cormorant or Biguá, is a phalacrocoracid bird distributed from the south of the USA to Cape Horn, Patagonia (Orta 1992). The species is widespread in Argentina and occupies a spectrum of wetlands in fresh, brackish and salt waters. They are opportunistic and generalist ichthyophagous feeders, foraging predominantly on fish and less intensively on crustaceans and mollusks, that usually exhibit a strong site fidelity (Casaux et al. 2009). In Argentina, the digenean fauna of P. brasilianus, was studied during several opportunities, and at present 11 digenean species belonging to 10 genera and four families have been reported: Austrodiplostomum mordax Szidat and Nani, 1951, Dolichorchis bonariensis Ostrowski de Núñez, 1970, Hysteromorpha triloba (Rudolphi, 1819), Neodiplostomum travassosi Dubois, 1937, Posthodiplostomum obesum Lutz, 1928 (Diplostomidae); Drepanocephalus spathans Dietz, 1909, Ignavia olivacei Ostrowski de Núñez, 1967, Paryphostomum fragosum (Dietz, 1909) (considered as species inquirenda by Kostadinova et al. 2002), Paryphostomum segregatum Dietz, 1909, (Echinostomatidae); Odhneria odhneri Travassos, 1921 (Microphallidae), and Ribeiroia ondatrae (Price, 1931) (Psilostomidae) (Lunaschi et al. 2007). Thirteen specimens of P. brasilianus were captured by shotgun between 1999 and 2004 in three areas from the Chaqueña Subregion of Argentina, defined according to Morrone (2001). Eleven birds were collected in Lacombe Lagoon (35°49’ S, 57°49’ W), Lezama, Buenos Aires Province (La Pampa biogeographic province), one in La Marcela farm (26°17’ S, 59°06’ W), Pirané, Formosa Province, and one in Clorinda (25°17’ S, 57°43’ W), Pilcomayo, Formosa Province (Chaco biogeographic province). The host birds were captured with authorization of Ministerio de Asuntos Agrarios of Buenos Aires Province and Ministerio de la Producción y Ambiente of Formosa Province. The birds were dissected in the field; the viscera were preserved in 10% formalin and transported to the laboratory for examination. The viscera were examined under stereoscopic microscopy, and the helminths were removed and stored in 70% ethanol. The digeneans were stained with a 1:6 dilution in 96% ethanol of hydrochloric carmine, dehydrated and mounted in Canada balsam. Photomicrographs were taken using a Zeiss Axioplan 2 Microscope. Measurements are given in micrometers (μm). The taxonomy of digeneans is given in accordance to Gibson et al. (2002), Jones et al. (2005) and Bray et al. (2008), and the parasitic indexes used were based on Bush et al. (1997). The helminths were deposited in the Helminthological Collection of the Museo de La Plata (MLP), La Plata, Argentina. The abbreviations of the metrical features are as follows: Ho-Ae: distance Holdfast organ-anterior end; Vf-Ae: Distance vitelline folliclesanterior end. Ratios: Pt/At: Posterior testis width/ Anterior testis width; B/Ho: Body length/Holdfast organ length; B/E: Body length/Egg length. Ten digenean species (four diplostomids, three echinostomatid, one strigeid, one psilostomid, and one prosthogonimid) were found (Table 1). Subclass Digenea Carus, 1863 Family Diplostomidae Poirier, 1886 Austrodiplostomum Szidat and Nani, 1951 Austrodiplostomum mordax Szidat and Nani, 1951 (Figure 1, Table 2). Adults of this species parasitizing P. brasilianus from Buenos Aires Province were described by Szidat and Nani (1951). Dubois (1970) synonymized A. mordax with A. compactum (Lutz, 1928). Later, Ostrowski de Núñez (1982) recognized both species as valid mainly based

Phalacrocorax brasilianus (Gmelin, 1789), commonly known as the Neotropic Cormorant or Biguá, is a phalacrocoracid bird distributed from the south of the USA to Cape Horn, Patagonia (Orta 1992).The species is widespread in Argentina and occupies a spectrum of wetlands in fresh, brackish and salt waters.They are opportunistic and generalist ichthyophagous feeders, foraging predominantly on fish and less intensively on crustaceans and mollusks, that usually exhibit a strong site fidelity (Casaux et al. 2009).
Thirteen specimens of P. brasilianus were captured by shotgun between 1999 and 2004 in three areas from the Chaqueña Subregion of Argentina, defined according to Morrone (2001).Eleven birds were collected in Lacombe Lagoon (35°49' S, 57°49' W), Lezama, Buenos Aires Province (La Pampa biogeographic province), one in La Marcela farm (26°17' S, 59°06' W), Pirané, Formosa Province, and one in Clorinda (25°17' S, 57°43' W), Pilcomayo, Formosa Province (Chaco biogeographic province).The host birds were captured with authorization of Ministerio de Asuntos Agrarios of Buenos Aires Province and Ministerio de la Producción y Ambiente of Formosa Province.The birds were dissected in the field; the viscera were preserved in 10% formalin and transported to the laboratory for examination.The viscera were examined under stereoscopic microscopy, and the helminths were removed and stored in 70% ethanol.The digeneans were stained with a 1:6 dilution in 96% ethanol of hydrochloric carmine, dehydrated and mounted in Canada balsam.Photomicrographs were taken using a Zeiss Axioplan 2 Microscope.Measurements are given in micrometers (μm).The taxonomy of digeneans is given in accordance to Gibson et al. (2002), Jones et al. (2005) and Bray et al. (2008), and the parasitic indexes used were based on Bush et al. (1997).The helminths were deposited in the Helminthological Collection of the Museo de La Plata (MLP), La Plata, Argentina.The abbreviations of the metrical features are as follows: Ho-Ae: distance Holdfast organ-anterior end; Vf-Ae: Distance vitelline folliclesanterior end.Ratios: Pt/At: Posterior testis width/ Anterior testis width; B/Ho: Body length/Holdfast organ length; B/E: Body length/Egg length.
Adults of this species parasitizing P. brasilianus from Buenos Aires Province were described by Szidat and Nani (1951).Dubois (1970) synonymized A. mordax with A. compactum (Lutz, 1928).Later, Ostrowski de Núñez (1982) recognized both species as valid mainly based on morphological differences of the larval stages and on the infection site of metacercariae.Most recently, Dronen (2009) considered A. compactum a synonym of A. mordax, recognizing as members of this species the specimens found parasitizing P. brasilianus from Venezuela by Lutz (1928), Nasir and Diaz (1972), and the specimens represented by figures 8 and 9 of Ostrowski de Núñez (1982).Although our specimens are smaller than those previously described from Venezuela and Argentina, they have similar morphological characteristics (Table 2).
Austrodiplostomum ostrowskiae Dronen, 2009 (Figure 2, Table 3).This species was described recently by Dronen (2009) parasitizing the small intestine of Phalacrocorax auritus (Lesson) (Phalacrocoracidae) from Texas, USA.The specimens studied here are larger than previously described for P. auritus (Table 3), but the morphological characters are in full agreement with this species.Moreover, Dronen (2009) considered members of A. ostrowskiae the specimens described as A. mordax by Ostrowski de Núñez (1970;1977), those reported as A. compactum by Dubois and Macko (1972), Fedynich et al. (1997), and Rietschel and Werding (1978), and the specimens represented by figures 10 and 11 of Ostrowski de Núñez (1982) from Argentina.We consider our specimens to be A. ostrowskiae, given that they present similar morphological and morphometric characters to those reported elsewhere (Table 3).The finding of A. ostrowskiae in Formosa Province extends its geographical distribution to the Chaco biogeographic province.
This species was previously reported by Ostrowski de   Núñez (1970) parasitizing the intestine of P. brasilianus from Buenos Aires and Córdoba Provinces.The finding of H. triloba parasitizing this host from Pirané extends its geographical distribution to Formosa Province.
In Argentina, this species was previously reported parasitizing the stomach of P. brasilianus from Buenos Aires city (Ostrowski de Núñez 1968).It was also reported parasitizing Spheniscus magellanicus (Forster, 1781) from La Plata Zoological Garden (Boero et al. 1972) and Ardea alba egretta Gmelin, 1789 from De Monte Lagoon, Buenos Aires Province (Labriola and Suriano 1998).The finding of R. ondatrae in Formosa Province extends its geographical distribution to the Chaco biogeographic province.Werding 1978).Kostadinova et al. (2002) transferred this species to Paryphostomum Dietz, 1909, mainly based on the morphology and size of the collar spines.Our record is the first from Argentina, extending the geographical distribution of P. parvicephalum to the Chaco biogeographic province.
This species was reported parasitizing the intestine of P. brasilianus from Brazil, Venezuela, Gulf of Mexico, Colombia and Paraguay (Kostadinova et al. 2002).It  was also reported parasitizing P. auritus from Gulf of Mexico and Sula leucogaster from Colombia (Rietschel and Werding 1978;Fedynich et al. 1997).In Argentina D. spathans was found parasitizing P. brasilianus from Buenos Aires city by Ostrowski de Núñez (1966;1968).Our finding of D. spathans parasitizing P. brasilianus from Formosa Province represents a new geographical record and extends its geographical distribution to the Chaco biogeographic province.
*Calculated from original description