Molecular Phylogeny of the Widely Distributed Marine Protists, Phaeodaria (Rhizaria, Cercozoa)

Abstract

Phaeodarians are a group of widely distributed marine cercozoans. These plankton organisms can exhibit a large biomass in the environment and are supposed to play an important role in marine ecosystems and in material cycles in the ocean. Accurate knowledge of phaeodarian classification is thus necessary to better understand marine biology, however, phylogenetic information on Phaeodaria is limited. The present study analyzed 18S rDNA sequences encompassing all existing phaeodarian orders, to clarify their phylogenetic relationships and improve their taxonomic classification. The monophyly of Phaeodaria was confirmed and strongly supported by phylogenetic analysis with a larger data set than in previous studies. The phaeodarian clade contained 11 subclades which generally did not correspond to the families and orders of the current classification system. Two families (Challengeriidae and Aulosphaeridae) and two orders (Phaeogromida and Phaeocalpida) are possibly polyphyletic or paraphyletic, and consequently the classification needs to be revised at both the family and order levels by integrative taxonomy approaches. Two morphological criteria, 1) the scleracoma type and 2) its surface structure, could be useful markers at the family level.

Gazelletta kashiwaensis sp. nov. (Medusettidae, Phaeodaria, Cercozoa), Its Morphology, Phylogeny, Distribution, and Feeding Behavior

“…The single‐cell PCR was conducted following the protocol written in Nakamura et al. (), and phylogenetic trees were constructed with other cercozoan sequences obtained from NCBI database (Table ).…”

“…Phaeodarians had been considered to be closely related to Radiolaria (Haeckel ); however, it was confirmed that Phaeodaria are a monophyletic group within Thecofilosea of the phylum Cercozoa (Nakamura et al. ; Nikolaev et al. ; Polet et al.…”

“…There is a paucity of information especially in the subtropical North Pacific (Nakamura and Suzuki ), although this sea area is known for high species diversity affecting the local ecosystem and fisheries. The investigations targeted on phaeodarians were, therefore, conducted in the area, and some fragile phaeodarians were collected by our modified sampling method (described in Materials and Methods).…”

Optics-based surveys of large unicellular zooplankton: a case study on radiolarians and phaeodarians

“…These two groups are phylogenetically close, according to the branching pattern in the phylogenetic tree based on an 18S rDNA analysis (Nakamura et al 2015), and the presence of a colony with an empty skeleton presumably reflects the genetic relationship between the two groups.…”

“…Phaeodaria have siliceous skeletons, and their overall appearance is similar to that of radiolarians. Yet, molecular studies have revealed that this group is phylogenetically different from Radiolaria (Nikolaev et al 2004, Sierra et al 2013, Nakamura et al 2015. Phaeodarians now belong to the phylum Cercozoa, included in Rhizaria (SAR), together with Radiolaria and Foraminifera (Howe et al 2011, Adl et al 2012.…”