Utility of small and large subunit rRNA genes for morphospecies discrimination and phylogenetic inference in the order Tintinnida (Ciliophora, Spirotrichea) (19F)

SANTOFERRARA L., ; MCMANUS G.; ALDER

Oslo

Congreso; Protist 2012.; 2012

International Society of Protistology (ISOP) International Society of Evolutionary Protistology (ISEP)

Knowing the degree of correlation between molecular and morphological characters in protists iscrucial to understand their diversity, biogeography, and ecological roles. We evaluated the small and large subunit rDNA (SSU and LSU, respectively) for their ability to discriminate morphospecies of tintinnid ciliates. Multiple individuals from 29 morphospecies were classified by lorica morphology and sequenced (21 new species for SSU and all of them new for LSU). Two hypervariable SSU regions (V4 and V9) were examined separately. LSU showed a gap in distances within and between species, and discriminated the maximum number of phylotypes(86% at 1% cut-off), thus being a promising barcoding tool. V9 provided the poorermorphospecies delimitation, and even SSU and V4 lumped together several distinctive morphospecies. Although we also found similar morphospecies with divergent SSU and LSU (pseudocryptic species), a general concordance between morphology and sequences was observed at the species level. The agreement between both criteria was lower above the species level, and some phylogenetic relationships remained poorly resolved according to inferences based on either SSU or SSU+LSU. Both analyses indicated the monophyly of the genera Tintinnidium and Eutintinnus, and the clustering of Helicostomella, Stenosemella, the paraphyletic Tintinnopsis, and some species of the polyphyletic Favella.