Abstract Detail

Systematics Section / ASPT

Gottschling, Marc [1], Plötner, Jörg [2], Willems, Helmut [3], Keupp, Helmut [1].

Molecular systematics of calcareous dinoflagellates.

Among myriads of species of alveolates, organisms producing calcareous structures are exclusively found in a small group of peridinoid dinoflagellates (‘calcareous dinoflagellates’, Calciodinelloideae). These calcareous structures either are cysts formed during the life cycle or are found as vegetative stages, which may be evolutionarily derived from such cysts. The potential to produce calcareous structures has been considered as apomorphic arguing for the monophyly of Calciodinelloideae. The phylogenetic relationships of calcareous dinoflagellates are investigated using molecular data from the ribosomal 5.8S rRNA and the Internal Transcribed Spacers. Calciodinelloideae are only monophyletic when a few non-calcareous taxa are included. They fall into three monophyletic assemblages: a clade comprising species of Ensiculifera and Pentapharsodinium (E/P-clade), Scrippsiella s.l. (including cyst taxa such as Calcigonellum, Calciodinellum, and Pernambugia), and a heterogeneous group (T/P-clade) of calcareous (e.g., Thoracosphaera) and non-calcareous taxa (e.g., the highly toxic Pfiesteria). The non-calcareous taxa nested in Calciodinelloideae have probably lost calcification secondarily. Molecular results do not contradict general evolutionary scenarios provided by previous investigations on archeopyle morphology and ultrastructure of the cyst wall. Molecular data suggest the existence of numerous cryptic taxa showing genetic, but not morphological, variation (especially in Scrippsiella). Closely allies have a wide hydrographic range and occur (at least partly) sympatrically in cold through tropical seas of the world.

1 - Freie Universität Berlin, Fachbereich Geologische Wissenschaften – Fachricht, Malteserstraße 74-100, Haus D, Berlin, Berlin, D-12249, Germany
2 - Humboldt Universität Berlin – Museum für Naturkunde, Institut für Systematische Zoologie, Invalidenstraße 43, Berlin, Berlin, D-10115, Germany
3 - Universität Bremen, Fachbereich Geowissenschaften – Historische Geolog, Postfach 33 04 40, Bremen, Bremen, D-28359, Germany

Keywords:
phylogeny
ITS
Calciodinelloideae
5.8S rRNA
distribution
cyst
theka
morphology
archeopyle
cyst wall ultrastructure.

Presentation Type: Paper
Session: 2-1
Location: Cottonwood A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 8:00 AM
Abstract ID:216