Corynosoma australe Johnson, 1937 and C.cetaceum Johnson & Best, 1942 (Acantocephala: Plymorphidae) from marine mammals and fishes in Argentinian waters: allozyme markers and taxonomic status.

SARDELLA,N., S.MATTIUCCI, J.T.TIMI, R.O.BASTIDA, D.H.RODRIGUEZ Y G.NASCETTI; RODRIGUEZ, DIEGO

SYSTEMATIC PARASITOLOGY

SPRINGER

Año: 2005 vol. 61 p. 143 - 156

0165-5752

Genetic and morphological studies were carried out on acanthocephalans belonging to Corynosoma Lu¨ he,n 1904 and referable to the species C. cetaceum Johnston & Best, 1942 and C. australe Johnston, 1937, which were recovered from both de.nitive and intermediate hosts in Argentinian waters. The aims were to estimate the level of genetic di.erentiation between the two taxa at any stage of their life-cycle, to provide genetic (allozyme) markers for their recognition and to analyse the systematic status of both taxa. Acanthocephalans were collected from the stomach and intestine of Arctocephalus australis (Zimmerman), the intestine of Mirounga leonina (Linnaeus) and the stomach of Pontoporia blainvillei Gervais & D?Orbigny (de.nitive hosts) in Argentinian waters. Alternative alleles at all the 13 enzymatic loci studied were observed for C. australe and C. cetaceum. The specimens from the stomach of both P. blainvillei and A. australis were identi.ed, on the basis of the great number of diagnostic loci found, as C. cetaceum; those from intestine of both A. australis and M. leonina as C. australe. A high level of genetic di.erentiation (DNei=¥: INei=0.00) between the two taxa was found, suggesting a generic distinction between the two species. Cystacanths of the two species from the body-cavity of the .sh Cynoscion guatucupa (Cuvier) collected from the same geographical area were identi.ed genetically. Morphological patterns, such as the number of hooks and hook rows on the proboscis, the distribution of somatic and genital armature, and other morphometric and meristic di.erences, in addition to ecological data, enabled the identi.cation of these two species at cystacanth, juvenile and adult stages. However, a number of morphological and morphometric features of the Argentinian material were di.erent to those of C. australe and C. cetaceum described from other regions of the world.Corynosoma Lu¨ he,n 1904 and referable to the species C. cetaceum Johnston & Best, 1942 and C. australe Johnston, 1937, which were recovered from both de.nitive and intermediate hosts in Argentinian waters. The aims were to estimate the level of genetic di.erentiation between the two taxa at any stage of their life-cycle, to provide genetic (allozyme) markers for their recognition and to analyse the systematic status of both taxa. Acanthocephalans were collected from the stomach and intestine of Arctocephalus australis (Zimmerman), the intestine of Mirounga leonina (Linnaeus) and the stomach of Pontoporia blainvillei Gervais & D?Orbigny (de.nitive hosts) in Argentinian waters. Alternative alleles at all the 13 enzymatic loci studied were observed for C. australe and C. cetaceum. The specimens from the stomach of both P. blainvillei and A. australis were identi.ed, on the basis of the great number of diagnostic loci found, as C. cetaceum; those from intestine of both A. australis and M. leonina as C. australe. A high level of genetic di.erentiation (DNei=¥: INei=0.00) between the two taxa was found, suggesting a generic distinction between the two species. Cystacanths of the two species from the body-cavity of the .sh Cynoscion guatucupa (Cuvier) collected from the same geographical area were identi.ed genetically. Morphological patterns, such as the number of hooks and hook rows on the proboscis, the distribution of somatic and genital armature, and other morphometric and meristic di.erences, in addition to ecological data, enabled the identi.cation of these two species at cystacanth, juvenile and adult stages. However, a number of morphological and morphometric features of the Argentinian material were di.erent to those of C. australe and C. cetaceum described from other regions of the world.