On-line version ISSN 1984-2961
Rev. Bras. Parasitol. Vet. vol.21 no.2 Jaboticabal Apr./June 2012
Contracaecumovale (Nematoda: Anisakidae) de Rollandia rolland Quoy & Gaimard 1824 (Aves, Podicipedidae) na Argentina
Noelia Adelina Galeano; Ruben Daniel Tanzola
Laboratorio de Patología de Organismos Acuáticos, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur - UNS, Bahía Blanca, Argentina
Necropsy on 15 specimens of white-tufted grebe, Rollandiarolland, caught in the Mar Chiquita and Chascomús lagoons (Buenos Aires province), revealed the presence of Contracaecumovale (Linstow, 1907). This nematode shows a marked specificity for podicipediform birds. The specimens were identified from morphological study on features such as cephalic and esophageal structures and caudal papillae, using both optical and scanning electron microscopy. This is the first record of C. ovale parasitizing R. rolland in Argentina.
Keywords: Contracaecum ovale, Nematoda, Rollandia rolland, Podicipedidae.
Necropsia de 15 espécimes de mergulhão-de-orelha-branca, Rollandiarolland, coletados nas lagoas Mar Chiquita e Chascomús (Província de Buenos Aires), revelou a presença de Contracaecumovale (Linstow, 1907). Esse nematóide tem uma marcada especificidade pelas aves podicipediformes. Os espécimes foram identificados a partir de características, tais como estruturas morfológicas cefálicas e esofágicas e papilas caudais, utilizando-se microscopia óptica e microscopia eletrônica de varredura (MEV). Esse é o primeiro registro de C. ovale parasito de R. rolland na Argentina.
Palavras-chave: Contracaecum ovale, Nematoda, Rollandiarolland, Podicipedidae.
Contracaecumovale (Linstow, 1907) is an ascaridoid nematode with pronounced specificity for podicipediform hosts. It was first described in Podiceps cristatus from Germany. Cram (1927) described this species in the same host and Baylis (1939) included it in a list of the parasites of British birds. Subsequently, Mozgovoi (1953) described it briefly in P. cristatus from Russia. Vuylsteke (1953) recorded C. ovale in P.ruficolliscapensis from the Congo. Macko (1961) described it in P. griseigena and P. nigricollis from the Czech Republic. The only previous record from the Neotropical region is that of Hartwich (1964) in Podilymbus podiceps in Brazil. Stock and Holmes (1987) cited C. ovale as a member of the parasite communities of P.grisegena, P.nigricollis and P.auritus in Canada. To the best of our knowledge, some details of the external morphology of this species remain unknown.
This note reports C. ovale in the white-tufted grebe, Rollandiarolland, for the first time in Argentina. White-tufted grebes are the most common grebe in lakes and lagoons throughout Argentina, from Misiones to Tierra del Fuego (STORER, 1967; FJELDSA, 2004). In this paper, C. ovale is described using optical microscopy and scanning electron microscopy (SEM).
The helminth specimens, which belong to the author's personal collection, were obtained between 1983 and 1985 from 15 individuals of R. rolland (Aves: Podicipediformes) that were killed using a shotgun (with permission for scientific hunting granted by the Fauna Directorate, Ministry of Agrarian Affairs, Government of the Province of Buenos Aires) in the Mar Chiquita lagoon (n = 12) (37º 46' S and 57º 27' W) and Chascomús lagoon (n = 3) (35º 40'S and 58º 00' W) in Buenos Aires province. Once in the laboratory, the birds were dissected and nematodes were collected from the stomach and fixed and stored in 5% formalin. Some specimens were cleared in lactophenol and examined by means of optical microscopy. Drawings were made with the aid of a camera lucida. Measurements, in millimeters, were expressed as the mean followed by the range in parentheses. Other specimens, fixed in 5% formalin were dehydrated in acetone, dried using the CO2 critical point method and observed and photographed using scanning electron microscopy (SEM) (Evoup/LEO). The spatial location of the male's papillae was described in accordance with Fagerholm (1991). The voucher specimen was deposited in the Helminthological collection of the Museo de la Plata, Argentina (nº MLP 6313). The measurements made in this study and those given by previous authors are presented in Table 1. Morphological details are shown in Figures 1-8.
The entire body of C. ovale is transversally striated (Figure 2). The lips are mostly oval in shape with two small auricles (Figure 3). There are two large double papillae on the dorsal lip and one on each ventrolateral lip (Figure 3) and, additionally, an amphid is present on each ventrolateral lip. The interlabia were triangular in shape and shorter than the lips (Figure 3). The deirids were inconspicuous and button-shaped (Figure 4)
Measurements on male specimens (n = 3): body length 18.5 (18-19); maximum body width 0.69 (0.67-0.72); distance from anterior end to nerve ring and deirids 0.09 (0.08-0.1) and 0.69, respectively; esophagus length (n = 1) 3.4; intestinal caecum length (n = 1) 2.7; ventriculus length (n = 1) 0.16; ventricular appendix length (n = 1) 0.70; spicules of equal length, reaching almost half of the body; spicule length (n = 1) 2.87; and tail length 0.20 (0.17-0.23). The caudal extremity was conical, bearing 12-16 pairs of precloacal papillae. The precloacal transverse stria ("pt") zone included three pairs of precloacal papillae (Figure 5). There was one double paracloacal papilla (sensu FAGERHOLM, 1991) and five pairs of single postcloacal papillae: two subventral pairs, two sublateral pairs ("laterodorsal" sensu HARTWICH, 1964) and one pair of phasmids at the end (Figure 6).
The distal spicule tip was short and pointed; the length of the free distal end was longer than the spicule width (0.013 versus 0.011). Following Fagerholm's approach (1989), the measurements of the distal end of the spicule (n = 1) in µm were: A-B: 12.6; A-C: 16.3; A-D: 35.6; Dist B*-Bº: 12.6; E-F: 8.2; E-H: 23.7; E-I: 30.4; and F-G: 11.1 (Figure 7)
Measurements on female specimen (n = 1): body length 31.85; maximum body width 0.86; distance from anterior end to nerve ring and deirids 0.45 and 0.54 respectively; esophagus length 3.8; intestinal caecum length 2.57; ventricular appendix length 1.1; vulva in anterior half of the body and tail length 0.65 (Figure 8).
The information provided by Mozgovoi (1953) coincides with that of Cram (1927) and so it was not included in Table 1.
The morphology and dimensions of our specimens were concordant with previous reports (CRAM, 1927; MOZGOVOI, 1953; MACKO, 1961; HARTWICH, 1964). Although the complexity of the lips was best discerned by Hartwich (1964), the ultrastructural observations made in the present report showed two small auricles and that the interlabia was one third of the lip height and triangle-shaped, in conformity with this author's findings. Fagerholm (1989) considered that the length of the spicules, morphology of the distal end of the spicule and number and distribution of caudal papillae in the males were other good taxonomic criteria. The number and distribution pattern of the caudal papillae agree with those of previous descriptions (CRAM, 1927; HARTWICH, 1964), but the details of the distal end of the spicules at ultrastructural level are described for the first time in the present paper. Macko (1961) and Cram (1927) reported 10 pairs of precloacal papillae, but Hartwich (1964) reported 29-35 pairs of precloacal papillae. Previous authors reported a wide range of intraspecies variation with regard to the number of precloacal papillae in anisakids: 60-81 pairs in C. osculatum (FAGERHOLM, 1989), 23 - 49 in C. ogmorhini (FAGERHOLM; GIBSON, 1987) and 44 - 61 in Terranovagaleocerdonis (TANZOLA; SARDELLA, 2006). For this reason, we can accept that the differences observed in relation to Hartwich's specimens may correspond to such intraspecies variation.
In Argentina, several species of Contracaecum have been reported parasitizing birds from freshwater, brackish water and marine ecosystems. Contracaecummicrocephalum (Rudolphi, 1809) has been described parasitizing the Ardeidae species Ardea cocoi Linnaeus, Egretta alba (Gmelin, 1789), Nycticoraxnycticorax (Gmelin, 1789) and Casmerodiusalbusegretta (Lineé, 1766) in Buenos Aires province and C. multipapillatum has been described parasitizing E. alba (BOERO; LED, 1971; NAVONE et al., 2000). Contracaecumtravassosi (Gutierrez, 1943) has been described in Phalacrocorax atriceps (= P.albiventer) (Lesson, 1831). Garbin et al. (2007) redescribed C. pelagicum (Johnston and Mawson, 1942) in Thalassarche melanophris Temminck and Spheniscus magellanicus Foster. In the latter host, Pazos et al. (2003) found C. spheniscus Boero and Led (1970) and C.chubutensis in P.atriceps King (GARBIN et al., 2008). The last three species came from Chubut province in Patagonia. This is the first record of C. ovale in R. rolland in Argentina, and it confirms the marked specificity of this species for podicipediform birds.
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Laboratorio de Patología de Organismos Acuáticos, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur
San Juan, 670
CP 8000, Bahía Blanca, Buenos Aires, Argentina
Received April 1, 2011
Accepted May 29, 2011