Establishing an Agenda for Calcareous Dinoflagellate Research (Thoracosphaeraceae, Dinophyceae) including a nomenclatural synopsis of generic names

Abstract

Calcareous dinoflagellates are considered to be a monophyletic group of peridinoid taxa that have the potential to produce calcified exoskeletal structures during the life cycle, or that derive from such forms. Frequently, these calcareous bodies are excellently preserved in the fossil record and have received increased attention during the past three decades with regard to their use in biostratigraphy, climate and environmental reconstruction. Fossil and extant taxa have been classified in various, partly concurring, systematic concepts, using character complexes of the theca, cyst wall ultrastructure and archaeopyle/operculum morphology. The significance of such character complexes is briefly discussed in the light of molecular data that have been accumulated during the past decade. Over the years, the number of published taxonomic names has increased, partly due to nomenclatural changes. We propose that the entirety of calcareous dinoflagellates, and non-calcareous relatives derived from them, is accommodated in a single family of the order Peridiniales, the Thoracosphaeraceae, combining the former segregated taxonomic units Calciodinelloideae, a subfamily within Peridiniaceae, and Thoracosphaerales, a separate dinoflagellate order. As a result of a meeting of calcareous dinoflagellate specialists, we outline major subjects that are in need of re-investigation and -evaluation (an Agenda for Calcareous Dinoflagellate Research). In order to contribute to a consistent and stable nomenclature and taxonomy of calcareous dinoflagellates, we list 97 published generic names assigned to known calcareous dinoflagellates in a nomenclatural synopsis, with species names indicating their types and information on type locality and stratigraphy. We evaluate the status of these names-whether validly published and, if so, whether legitimate-, a crucial first step for any revisionary work in the future.

SAME BUT DIFFERENT: TWO NOVEL BICARINATE SPECIES OF EXTANT CALCAREOUS DINOPHYTES (THORACOSPHAERACEAE, PERIDINIALES) FROM THE MEDITERRANEAN SEA1

“…2004), vastly exceeding the diversity known from the today recognized species in the global oceans. Among myriad species of the Alveolata, the potential to produce calcareous structures is restricted to (i.e., has been considered apomorphic for) the Thoracosphaeraceae, arguing for the monophyly of this group (Wall and Dale 1968, Janofske 1992, Elbrächter et al. 2008).…”

Diversity, distribution, and new phylogenetic information of calcareous dinoflagellates from the China Sea

“…Fensome et al (1993) classified those species producing calcareous hypnozygotes as well as related ones in the subfamily Calciodinellaceae. Elbrächter et al (2008) proposed that the entirety of calcareous dinoflagellates, and non‐calcareous relatives derived from them, should be accommodated in a single family of the order Peridiniales, the Thoracosphaeraceae, combining the subfamily Calciodinelloideae and Thoracosphaerales, a separate dinoflagellate order. Phylogenetic analyses revealed that the potential to produce calcareous structures is apomorphic within alveolates, and non‐calcareous taxa nesting with calcareous dinoflagellates may have reduced calcification secondarily (Gottschling et al, 2005).…”

A Discussion and Proposal Concerning the Use of the Term Calcispheres

“…Some genera and species of microfossils previously classified within the calcispheres have been assigned to the Dinophyceae (calcareous cysts of dinoflagellates) on the basis of definitive morphological criteria. Among these taxa are most of the genera listed by Elbrächter et al . (2008).…”