Morphological anomalies of Stegophorus macronectes (Johnston & Mawson, 1942).

VIDAL V.; ORTIZ J.; DIAZ J.I.; RUIZ DE IBÁÑEZ, M.R.,; ZAFRILLA, B.,; BONETE, M.J.,; AMAT, M.; BARBOSA, A.

Lisboa, Portugal

Congreso; IX Congreso Iberico de Parasitología; 2009

Sociedad Portuguesa y Sociedad Española de Parasitologica

INTRODUCTION   Previous studies of gastrointestinal parasite fauna in chinstrap penguin (Pygoscelis antarctica) show Stegophorus macronectes as one of the most prevalent parasite in this host. It has also been cited in others six antartic species. During a study performed with optical microscopy different morphological patterns from the model described of Stegophorus sp. were observed. Such variation could correspond to different species. The patterns found were studied in detail with techniques of scanning electron microscopy and molecular biology. MATERIALS AND METHODS 34 chinstrap penguin from Deception Island (63º 00´ S, 60º 40’ W), in the South Shetlands Islands, were analyzed. Gastrointestinal packages were collected from carcasses found on the ground close to the breeding colonies, and preserved frozen at -20ºC until analyzed. Nematodes were isolated and conserved in ethanol 70%. For observation with the optical microscope they were clarified with lactofenol of Amman. Scanning electron microscopy was used to observe structures not clearly visible with the optical microscope. Previously the nematodes were prepared using the technique of Critical Point Dryers. Finally, a 18-S ribosomal DNA (18-S DNAr) fragment was sequenced. RESULTS   Throughout the identification of Stegophorus macronectes several morphological patterns have been found. Deirids were observed at different levels; esophagus and vestibule were moving backwards, which did not allow its differentiation. To take measurement was not possible as well. The lobes were folded giving different morphologies. Asymmetry in the denticles of the deirids and in the number of denticles of fold was observed. Sequences of two copies from different individuals were closed than copies from the same specimen. CONCLUSIONS   The different morphological patterns observed correspond to morphological alterations of a same species: S.macronectes. These alterations could be due to problems in the conservation of the samples. In this process cuticle would be given off and tended to move rostraly at the same time that the body of the parasite would be retracted. Denticles of fold can be increase in number in an asymmetric way (from 26-44 to 22-50). Deirids can present asymmetric modifications appearing in some instances with bifids ends.