title: Towards an Integrative Morpho-molecular Classification of the Collodaria (Polycystinea, Radiolaria).
abstract: Collodaria are ubiquitous and abundant marine radiolarian (Rhizaria) protists. They occur as either large colonies or solitary specimens, and, unlike most radiolarians, some taxa lack silicified structures. Collodarians are known to play an important role in oceanic food webs as both active predators and hosts of symbiotic microalgae, yet very little is known about their diversity and evolution. Taxonomic delineation of collodarians is challenging and only a few species have been genetically characterized. Here we investigated collodarian diversity using phylogenetic analyses of both nuclear small (18S) and large (28S) subunits of the ribosomal DNA, including 124 new sequences from 75 collodarians sampled worldwide. The resulting molecular phylogeny was compared to morphology-based classification. Our analyses distinguished the monophyletic clade of skeleton-less and spicule-bearing Sphaerozoidae from the sister clades Collosphaeridae (skeleton-bearing) and Collophidiidae (skeleton-less), while the Thalassicollidae was not retrieved as a monophyletic clade. Detailed morphological examination with electron microscopy combined with molecular analyses revealed many discrepancies, such as a mix between solitary and colonial species, co-existence of skeleton-less and skeleton-bearing specimens within the Collosphaeridae, as well as complex intraspecific variability in silicified structures. Such observations challenge a morphology-based classification and highlight the pertinence of an integrative taxonomic approach to study collodarian diversity.
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, UMR 7144, Team Diversity and Interactions in Oceanic Plankton, Station Biologique de Roscoff, CS90074, 29688 Roscoff cedex, France; CNRS, UMR 7144, Laboratoire Adaptation et Diversité en Milieu Marin, Place Georges Teissier, CS90074, 29688 Roscoff cedex, France. Electronic address: tristan.biard@sb-roscoff.fr.
authors.forename: Tristan
authors.initials: T
authors.lastname: Biard
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, UMR 7144, Team Diversity and Interactions in Oceanic Plankton, Station Biologique de Roscoff, CS90074, 29688 Roscoff cedex, France; CNRS, UMR 7144, Laboratoire Adaptation et Diversité en Milieu Marin, Place Georges Teissier, CS90074, 29688 Roscoff cedex, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Pillet
authors.affiliation: CNRS, UMR 7144, Laboratoire Adaptation et Diversité en Milieu Marin, Place Georges Teissier, CS90074, 29688 Roscoff cedex, France; Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, UMR 7144, Team Evolution of Plankton and Pelagic Ecosystems, Station Biologique de Roscoff, CS90074, 29688 Roscoff cedex, France.
authors.forename: Johan
authors.initials: J
authors.lastname: Decelle
authors.affiliation: Monterey Bay Aquarium Research Institute, 7700 Sandholdt road, Moss Landing CA 95039, United States.
authors.forename: Camille
authors.initials: C
authors.lastname: Poirier
authors.affiliation: Institute of Geology and Paleontology, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578 Japan.
authors.forename: Noritoshi
authors.initials: N
authors.lastname: Suzuki
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, UMR 7144, Team Diversity and Interactions in Oceanic Plankton, Station Biologique de Roscoff, CS90074, 29688 Roscoff cedex, France; CNRS, UMR 7144, Laboratoire Adaptation et Diversité en Milieu Marin, Place Georges Teissier, CS90074, 29688 Roscoff cedex, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Not
mesh_terms: D044822:Biodiversity; D004275:DNA, Ribosomal / Q000235:genetics; D008855:Microscopy, Electron, Scanning; D010802:Phylogeny; D056901:Rhizaria / Q000145:classification* / Q000235:genetics / Q000648:ultrastructure
chemical_list: D004275:DNA, Ribosomal
keywords: Collodaria; Radiolaria; integrative taxonomy; molecular phylogeny; polycystine; single-cell.