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Proposal of M onorhizochytrium globosum gen. nov., comb. nov. ( S tramenopiles, L abyrinthulomycetes) for former T hraustochytrium globosum based on morphological features and phylogenetic relationships
Author(s) -
Doi Kosaku,
Honda Daiske
Publication year - 2017
Publication title -
phycological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.438
H-Index - 44
eISSN - 1440-1835
pISSN - 1322-0829
DOI - 10.1111/pre.12175
Subject(s) - biology , chaetomium globosum , polyphyly , phylogenetic tree , type (biology) , zoospore , type locality , genus , phylogenetics , taxonomy (biology) , botany , taxon , type species , zoology , ecology , spore , clade , genetics , gene
SUMMARY Thraustochytrium is the type genus of the family T hraustochytriaceae in the class L abyrinthulomycetes. This genus is characterized by zoospore formation, namely, shape of the cell wall of sporangia and presence or absence of a proliferous body. However, there are several issues associated with the taxonomy of this genus, and these include polyphyletic taxa and overlapping of taxonomic features among species. In particular, the first and second species, T . proliferum and T . globosum , were described based on observations of the morphological features of natural samples in the absence of culture conditions. Before addressing the taxonomic issues associated with this genus, it is important to consider the taxonomic features of each species, i.e., the life history under culture conditions and the phylogenetic position. The objective of the present study was to isolate T . globosum , the second described species in the genus T hraustochytrium , from the type locality. We successfully isolated strain NBRC 112723, which exhibited characteristic features of T . globosum . Under culture conditions, strain NBRC 112723 exhibited taxonomic features observed in other thraustochytrid species. Our molecular phylogeny indicated that this strain isolated from the type locality was located in an unidentified thraustochytrid group; moreover, some strains located in this group exhibited characteristic features of strain NBRC 112723. We clearly distinguished T. globosum based on the taxonomic criteria used to classify the T. proliferum type species. Therefore, we propose the establishment of a new genus, M onorhizochytrium , for the species T. globosum in the family T hraustochytriaceae.