Molecular and morphological characterization of tintinnid ciliates

SANTOFERRARA L.; TOMARAS J.,; ZHANG H.,; ALDER V.A.

Seattle, USA

Simposio; ISOP Meeting. Joint Meeting of the Phycological Society of America, International Society of Protistologists & Northwest Algal Symposium; 2011

Society of Protistologists, Phycological Society of America,

Despite recent growth in genetic and genomic approaches to understanding the diversity of protists, the relationship between DNA sequences and the classical criteria for species identification remains controversial. In this context, tintinnid ciliates represent a challenging case, as taxonomy is based mainly on the morphology of the lorica, a structure with questionable diagnostic value due to its plasticity. The aim of this study is to compare the molecular and morphological variability within and between tintinnid species from coastal waters of the North and South Atlantic. Individual organisms were photographed to document morphology and subjected to sequencing of the nuclear small subunit rDNA. Species in the genera Tintinnopsis, Tintinnidium, Helicostomella, Eutintinnus and Favella were analyzed. We found species showing morphological overlap but divergent sequences as well as species with different morphology but identical sequences. Species within the genus Tintinnopsis were in some cases more distant from species in their own genus than they were to those in Helicostomella or other genera previously sequenced, regardless of the presence of an agglomerated or hyaline lorica. These results are expected to contribute to accurate systematic and phylogenetic schemes for tintinnids.