GENETIC AND MORPHOLOGICAL EVIDENCES FOR THE EXISTENCE OF A NEW SPECIES OF CONTRACAECUM (NEMATODA: ANISAKIDAE) PARASITE OF PHALACROCORAX BRASILIANUS (GMELIN) FROM CHILE AND ITS GENETIC RELATIONSHIPS WITH CONGENERS FROM FISH-EATING BIRDS

LUCAS GARBIN; SIMONETTA MATTIUCCI; MICHELA PAOLETTI; D. GONZALEZ ACUÑA; GIUSEPPE NASCETTI

JOURNAL OF PARASITOLOGY

Allen Press

Año: 2010

0022-3395

Contracaecum australe n. sp. is described from the Neotropic cormorant Phalacrocoraxbrasilianus in Chile based on morphology and the sequences analysis of multiple loci, i.e.,mitochondrial cytochrome oxidase 2, mtDNA cox-2, the small subunit of the mitochondrial ribosomal RNA gene, rrnS, and the ITS-1 and ITS-2 regions of nuclear ribosomal DNA. Moreover, sequences analysis of the same genes was carried out on the morphospecies C. chubutensis Garbin et al. from Ph. atriceps. Further, genetic relationships between C. australe n. sp. and C. chubutensis with respect to the related congeners from fish-eating birds previously characterized genetically on the same genetic markers, i.e., C. rudolphii A, B, C, D, and E, C. septentrionale, C. microcephalum, C. bioccai, C. pelagicum, C. micropapillatum, C. gibsoni, and C. overstreeti, are presented. Several phylogenetic analyses (MP, NJ, and BI) inferred from mitochondrial genes (cox-2, rrnS) were congruent in depicting C. australe n. sp. and C. chubutensis as forming distinct clades, highly supported, from the remainder of the Contracaecum taxa considered; thus, it validates their specific status. Further, analyses of the ITS-1 andITS-2 sequence data of C. australe n. sp. and C. chubutensis supported their distinction with respect to the 2 sibling species, C. rudolphii D and C. rudolphii E previously detected from Phalacrocoracidae of Australia. Morphological analysis and the differential diagnosis of male specimens of C. australe n. sp. enabled the detection of differences in a number of characters, including spicule length, peculiar shape of male tail, paracloacal papillae disposition, and shape and bifurcation depth of interlabia. According to the genetic and morphological results obtained, the erection of a new taxon from fish-eating birds of the Austral region is given and its formal description is presented. Phylogenetic trees support both C. australe n. sp. and C. chubutensis as included in the same clade with the previously detected species from cormorants, i.e., C. rudolphii A, B, C, and C. septentrionale. The finding of C. australe n. sp. and C. chubutensis parasites of Ph. brasilianus and Ph. atriceps, respectively, appears to support a hostparasiteassociation between the C. rudolphii A, B, and C, C. septentrionale, C. chubutensis and C.australe n. sp., and different species of cormorants belonging to the genus Phalacrocorax.