Contracaecum rudolphii Hartwich (Nematoda, Anisakidae) from the Neotropical Cormorant, Phalacrocorax brasilianus (Gmelin) (Aves, Phalacrocoracidae) in southern Brazil

Contracaecum rudolphii Hartwich (Nematoda, Anisakidae) parasita de biguás (cormorões Neotropicais, Phalacrocorax brasilianus (Gmelin) (Aves, Phalacrocoracidae) na região Sul do Brasil

SCIENTIFIC COMMUNICATION

Contracaecum rudolphii Hartwich (Nematoda, Anisakidae) from the Neotropical Cormorant, Phalacrocorax brasilianus (Gmelin) (Aves, Phalacrocoracidae) in southern Brazil¹

Contracaecum rudolphii Hartwich (Nematoda, Anisakidae) parasita de biguás (cormorões Neotropicais, Phalacrocorax brasilianus (Gmelin) (Aves, Phalacrocoracidae) na região Sul do Brasil

José F. R. Amato; Cassandra M. Monteiro; Suzana B. Amato

Departamento de Zoologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul. Caixa Postal 15014, 91501-970 Porto Alegre, Rio Grande do Sul, Brasil. E-mail: [e-mail]; [e-mail]; [e-mail]

ABSTRACT

The present report is part of a larger study on the helminth fauna of Neotropical Cormorants, Phalacrocorax brasilianus (Gmelin, 1789) in Brazil, particularly, in the southernmost State of Rio Grande do Sul. The nematodes which were found loose in the proventriculus/ventriculus or in groups of adults of different ages and of L₃ and L₄ larval stages, forming eosinophylic granulomas had a prevalence of 100% in 47 Neotropical cormorants from Lago Guaíba, Municipality of Guaíba. The morphology of the labia/interlabia, the distribution pattern of the caudal papillae in males examined under scanning electron microscopy (SEM), and the tips of the spicules allowed determination of the species as Contracaecum rudolphii Hartwich, 1964 sensu lato (s. l.). This is the first record of C. rudolphii in southern Brazil.

Key words: Eosinophylic granulomas; Lago Guaíba; Rio Grande do Sul; SEM; taxonomy.

RESUMO

O presente trabalho é parte de um estudo maior sobre a helmintofauna dos cormorões Neotropicais conhecidos no Brasil como biguás, Phalacrocorax brasilianus (Gmelin, 1789), particularmente, no Estado do Rio Grande do Sul. Os nematóides que foram encontrados soltos no proventrículo/ventrículo ou em grupos compostos por adultos de várias idades e larvas de vários estágios (L₃ e L₄), formando granulomas eosinofílicos tiveram prevalência de 100% em 47 biguás do Lago Guaíba, Município de Guaíba. A morfologia dos lábios e dos interlábios, o padrão de distribuição das papilas caudais em machos examinados com microscópio eletrônico de varredura (MEV) e as extremidades dos espículos permitiram a determinação da espécie como Contracaecum rudolphii Hartwich, 1964 sensu lato (s. l.). Este é o primeiro registro de C. rudolphii na região Sul do Brasil.

Palavras-chave: Granulomas eosinofílicos; Lago Guaíba; MEV; Rio Grande do Sul; taxonomia.

HARTWICH (1964) revised Contracaecum Railliet & Henry, 1912, presenting a complete list of synonyms and hosts for five species he considered as belonging to the genus. That author used the labia/interlabia internal and external morphology, the distribution of distal papillae, and the morphology of the spicules' tip to characterize these species as he had done earlier (HARTWICH 1957), when nomenclatorial alterations on the systematics of the Ascaridoidea were introduced. The author stated that Ascaris microcephala Rudolphi, 1809, later becoming Contracaecum microcephalum (Rudolphi, 1809) Baylis, 1920, was morphologically similar to some specimens which Rudolphi had identified as Ascaris spiculigera Rudolphi, 1809, and declared, based on page priority, A. spiculigera a junior synonym of C. microcephalum. Other specimens also studied by Rudolphi at that time were identified as A. spiculigera, although belonged to a new species (still unnamed) for which the new name Contracaecum rudolphii Hartwich, 1964, was proposed.

FAGERHOLM (1988) discussed the pattern distribution of the caudal papillae, based on SEM, seen in several species of Contracaecum parasites of seals at different localities in high latitudes of the northern and southern hemispheres. That author suggested a special nomenclature for the caudal papillae, including information on C. rudolphii. Later, FAGERHOLM (1991), considered the importance of studying the caudal papillae in a broader sense, i.e., within the superfamily Ascaridoidea. Other morphological studies with SEM were conducted by Baruš et al. (2000), showing the labia and interlabia morphology as well as the distribution of the caudal papillae of C. rudolphii and by Abollo et al. (2001) who characterized the male posterior region and the caudal papillae distribution in specimens collected from the European Shag Phalacrocorax aristotelis (Linnaeus, 1761).

The final hosts of the species of Contracaecum are fish-eating birds (mostly Pelecaniformes) associated with fresh and marine waters and seals all over the world (Baruš et al. 2000). The main final hosts of C. rudolphii are birds of the genus Phalacrocorax Brisson, 1760 (ANDERSON 1992). THRELFALL (1982) recorded a concurrent infection by C. spiculigerum (= C. rudolphii) and Contracaecum multipapilatum (Rudolphi, 1819) Baylis, 1920 in the Doubled-crested Cormorant, Phalacrocorax auritus (Lesson, 1831) while ABOLLO et al. (2001) recorded concurrent infections by C. rudolphii and Contracaecum septentrionale Kreis, 1955 in the proventriculus of the European shag.

The Neotropical Cormorant, Phalacrocorax brasilianus (Gmelin, 1789), occurs from Tierra del Fuego, Patagonia, Argentina to coastal Texas, USA, the northernmost extreme of its known geographical distribution (DEL HOYO et al. 1992, apud FEDYNICH et al. 1997). The resident populations of this bird have been the subject of helminthological studies in southern Chile by Torres et al. (1981, 1982, 1983, 2000) and in the coastal Texas, USA by FEDYNICH et al. (1997), who compared the helminth community structure and pattern in sympatric populations of double-crested and Neotropical cormorants.

VICENTE et al. (1995a) published valuable information about the nematodes of Brazilian birds, mostly based on specimens deposited in the "Coleção Helmintológica do Instituto Oswaldo Cruz (CHIOC)", from the early 1920's to the late 1960's. VICENTE et al. (1995b) listed the nematodes of Brazilian ciconiiform birds, establishing new records, and later, VICENTE et al. (1996), made a brief description of four specimens of C. spiculigerum (= C. rudolphii) collected from P. brasilianus and the "anhinga", Anhinga anhinga (Linnaeus, 1758), from the States of Mato Grosso do Sul and Rio de Janeiro, which were deposited in the CHIOC. The present study is the first to identify the species of Contracaecum from P. brasilianus in Lago Guaíba, Municipality of Guaíba, Rio Grande do Sul, southern Brazil.

Forty-seven Neotropical cormorants, P. brasilianus were collected from Lago Guaíba, Municipality of Guaíba, Rio Grande do Sul, from 1999 to 2003, in accordance with the permit numbers 232/1999 and 064/2002, from Instituto Brasileiro do Meio Ambiente e dos Recursos Renováveis (IBAMA). Cormorants were frozen at -10ºC, as soon as possible, after the catch. Necropsies were performed in the Laboratório de Helmintologia, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul, Brazil. The nematodes were processed according to AMATO et al. (1991). Helminths were collected, counted, and cleaned in saline solution 0.85%. Later were fixed in AFA and preserved in 70°GL ethanol. For light microscopy (LM) some specimens were examined as temporary whole mounts in lactophenol (HUMASON 1972). For SEM, the nematodes with sectioned spicules were critical point dried, coated with carbon and gold, and examined with a Jeol (JSM-6060) scanning electron microscope. Measurements are in millimeters (mm) unless otherwise indicated, ranges are followed (between parentheses) by the mean ± the standard deviation values, and the number of specimens measured for a given character (when different than the total number of specimens measured). Morphological parameters follow HARTWICH (1964). Different developmental stages were identified according to HARTWICH (1964) and Huizinga (1966). The fourth larval stage (L₄) and immature adults were identified according to TORRES et al. (2000). The nomenclature for the pattern of male caudal papillae follows FAGERHOLM (1988). Ecological terms such as prevalence, intensity of infection, and mean intensity of infection follow MARGOLIS et al. (1982). Voucher specimens were deposited (in ethanol 70ºGL) in the CHIOC, Rio de Janeiro, Rio de Janeiro, Brazil.

Contracaecum rudolphii Hartwich, 1964

Figs 1-9

Description: based on 105 adult specimens (30 males and 30 females mounted in lactophenol and measured; five specimens mounted en face as well as four male tails mounted in lactophenol; and 46 specimens mounted on stubs for SEM).

General: nematodes of different ages and larval stages were found concentrated in the proventriculus/ventriculus (Fig. 1), forming ulcerated eosinophylic granulomas (Fig. 2) and feeding on blood. Three labia, usually hexagonal, without dentigerous ridges (Figs 3, 5 and 6); dorsal labium with 2 ovate papillae (Figs 5 and 6), each formed by the fusion of the two original papillae; 2 ventrolateral labia, each with 1 lateral, ovate papilla (Figs 3 and 5), also formed by the fusion of the two original papillae and 1 amphidial pore (Fig. 5 – arrows) and two auriculae (Fig. 6 – head arrows); interlabia well developed (Figs 3-5), with bifid distal ends (Fig. 7). Excretory pore opening bellow ventral interlabium. Esophagus with small, globular ventricle and a posterior ventricular appendix. Intestinal cecum directed anteriad.

Males (30 specimens): body 18-31 (25 ± 3.4) long, 306-598 µm (481 ± 7 µm) in maximum width. Muscular esophagus 2.4-3.8 (3.1 ± 0.5) long; intestinal cecum 2.1-2.9 (2.4 ± 0.3) long; ventricular appendix 0.8-1.2 (1.0 ± 0.1) long. Spicules similar, almost equal (Fig. 9); right spicule 4.5-7.5 (6.2 ± 0.9) long, left spicule 5.9-8.2 (7.1 ± 0.8) long; cloacal opening at 140-235 µm (205 ± 22 µm) from posterior end. Tail conic, with more than 30 pairs of proximal papillae, 1 or 2 pairs of ad-cloacal papillae (Fig. 8), 7 pairs of distal papillae, the first 2 pairs side by side; 2 ventrolateral and 2 dorso-lateral pairs (Fig. 8 – arrows). Phasmidial pores on top of smaller papillae, between ventrolateral papillae (Fig. 8). Body length/body maximum width ratio 47.9-68.6:1 (52.9 ± 3.3); body length/esophagus length ratio 7.1-10.9:1 (8.1 ± 0.7); body length/caudal length ratio 91.3-145.5:1 (122.7 ± 14.6); esophagus length/intestinal cecum length ratio 0.9-1.6:1 (1.3 ± 0.1); esophagus length/ventricular appendix length ratio 2.8-3.6:1 (3.2 ± 0.2); body length/mean length of spicules ratio 3.1-5.4:1 (3.8 ± 0.4).

Females (30 specimens): body 23-52 (41.8 ± 7.5) long, 0.5-1.1 (0.8 ± 0.1) wide. Muscular esophagus 2.4-5.4 (4.2 ± 0.8) long; intestinal cecum 1.6-3.6 (2.9 ± 0.6) long; ventricular appendix 0.6-1.5 (1.2 ± 0.2) long; anus 0.2-0.6 (0.4 ± 0.1) from posterior end. Vulva 9.7-21.3 (15.2 ± 2.5) from anterior end. Eggs 99-106 µm (105 ± 7 µm) long, 83-92 µm (91 ± 8 µm) wide. Phasmid apertures lateral. Body length/body maximum width ratio 36.6-66.5:1 (53.2 ± 6.1); body length/esophagus length ratio 8.7-13.2:1 (9.9 ± 0.8); body length/caudal length ratio 74.9-168.3:1 (101.8 ± 21.0); esophagus length/intestinal caecum length ratio 1.3-1.6:1 (1.5 ± 0.1); esophagus length/ventricular appendix length ratio 3.2-4.3:1 (3.7 ± 0.3). Vulva from anterior extremity x 100/body length ratio 29.7-46.5:1 (36.7 ± 3.6).

Host. Neotropical cormorant ("biguá"), Phalacrocorax brasilianus (Gmelin, 1789).

Site of infection. Proventriculus/ventriculus.

Locality. Lago Guaíba, Municipality of Guaíba, Rio Grande do Sul, Brazil (30°00'S, 51°15'W).

Prevalence. 100%.

Mean intensity of infection. 97.7 helminths/host.

Range of infection. 25-403 helminths/host.

Voucher specimens deposited. CHIOC numbers 35.488 and 35.489 (in ethanol 70ºGL).

Remarks. Generally, measurements and morphometrical ratios in our specimens were larger than those given by HARTWICH (1964), although these differences might be related to the fact that we only measured adult specimens, while Hartwich did not say if the measurements presented referred only to adult specimens. The distal end of the spicules (Fig. 9) and the number and position of caudal papillae (Fig. 8) when compared with the original description, confirm the identification of this species.

HARTWICH (1964) indicated the holotype, paratypes, type host, and type locality for C. rudolphii, stating (pg. 32): "Der Holotypus befindet sich in der Helminthensammlung des Instituts für Spezielle Zoologie und Zoologischen Museums der Humboldt-Universität zu Berlin unter der Katalog-Nr. 441a, die Paratypen unter Nr. 441b" [sic].

VICENTE et al. (1996) published morphometrical data and illustrations of specific diagnostic characters of C. spiculigerum (= C. rudolphii) allowing comparison with the specimens of the present report, which are larger. The illustrations provided by these authors of the en face anterior end cannot be accepted as representative of the species, as well as the indication of the presence of two labial papillae in each labium. HARTWICH (1964), in the original description of the species, and anteriorly HARTWICH (1957), when proposing the genus, mentioned the presence of two pairs of papillae in the dorsal labium, resulting from the fusion of the two original papillae. VICENTE et al. (1996) have also indicated the presence of five pairs of distal papillae, when the generic diagnosis indicates the presence of seven pairs.

Another discrepancy between Hartwich's description and that of VICENTE et al. (1996) are the egg sizes: 59-73 µm long by 41-59 µm wide and 50 µm long by 40 µm wide, respectively. The size of eggs in the specimens of C. rudolphii in the present work is larger than what has been indicated by these authors, and also have the phasmidial openings on top of the penultimate pair of distal papillae (Fig. 8 – arrows), as has been indicated by FAGERHOLM (1988) and ABOLLO et al. (2001). The shape of the labia and interlabia, as well as the papillae distribution on the male tails and the bifurcation of the interlabial extremities, agree with the illustrations provided by BARUš et al. (2000).

HARTWICH (1964) listed the ardeid "Casmerodius albus egretta (LINNAEUS, 1758) (Syn.: Ardea leuce Bryant). Brasilien (Rio Grande do Sul)" [sic], as one of the hosts for C. microcephalum, giving no additional information (author, collecting date, exact locality of capture, etc.), but indicating the deposit number in the collection: "Zoolog. Museum Berlin (Nº 1071)" [sic]. This is the only previous record of any species of Contracaecum in southern Brazil, but cannot be confirmed at the present time.

LI et al. (2005) presented genetic evidence for the existence of sibling species within the C. rudolphii complex (formed by C. rudolphii A and C. rudolphii B) collected from the Large Black Cormorant, Phalacrocorax carbo sinensis Blumenbach, 1798, in northeastern and central Italy, based on the first (ITS-1) and the second (ITS-2) internal transcribed spacers of ribosomal DNA (rDNA). As specimens of C. rudolphii from the proventriculus/ventriculus of P. brasilianus from Lago Guaíba still have to undergo examination at the molecular level to detect the eventual existence of sibling species the present work is the first to document the presence of C. rudolphii (s. l.) in P. brasilianus in southern Brazil.

ACKNOWLEDGEMENTS

To IBAMA for the permission to capture cormorants of Lago Guaíba; to Ludwig Buckup for the kindness of translating portions of HARTWICH (1964) into Portuguese; to Ronald D. Rocco for reviewing the English text; to CAPES for the scholarship given to the second author; and to the technicians of the Centro de Microscopia Eletrônica, UFRGS, for their valuable assistance.

Received in 04.IV.2006; accepted in 30.X.2006.

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Contribution number 478 of the Departamento de Zoologia, Universidade Federal do Rio Grande do Sul

Publication Dates

• Publication in this collection
  02 Feb 2007
• Date of issue
  Dec 2006

History

• Accepted
  30 Oct 2006
• Received
  04 Apr 2006