How many species? How many forms? Hidden biodiversity of merizocotyline monogeneans in batoids (Chondrichthyes: Elasmobranchii) from the coasts of the Argentine Sea

IRIGOITIA MANUEL MARCIAL; BRAICOVICH, PAOLA E; FARBER, MARISA D; TIMI JUAN TOMÁS

Brno

Simposio; 8th International Symposium on Monogenea; 2017

In order to study monogenean diversity from elasmobranch hosts in the Argentine Sea, olfactory sacs of 310 batoids, corresponding to six species of Arhynchobatidae and one species of Myliobatidae were examined. Representatives of the genus Empruthotrema spp. were found in seven host species. Haptoral morphology of all worms was similar to that of E. raiae, a species known from European batoids. However, when the male copulatory organs (MCO) were thoroughly studied under SEM, after digestion with Proteinase K, three groups were identified according to the size and morphology. A first group with MCO short and curved, parasitizing Psammobatis normani, P. rudis, P. bergi and Atlantoraja castelnaui; a second group with MCO long and slightly curved, from Sympterygia bonapartii and S. acuta; and a third group with MCO long, straight and blunt from Myliobatis goodei. In order to corroborate these results by genetic studies, sequences of 28S ribosomal DNA were obtained from specimens of each host species. Generated sequenced were compared for similarities against sequences retrieved from Genbank and phylogenetic analysis were performed including E. quindecima and E. dasyatidis. Genetic and morphological results agreed in determining the same groupings of specimens from each host species, whereas species retrieved from Genbank clustered in a different clade, providing evidences on the existence of 3 putative new species of Empruthotrema in the Argentine Sea. Co-evolutionary processes giving rise to the obtained phylogenies and the effect of environmental factors (depth, temperature, salinity) on them are discussed.