Morphological and molecular phylogenetic analysis of the high triglyceride‐producing marine diatom, F istulifera solaris sp. nov. ( B acillariophyceae)

Summary F istulifera sp. strain JPCC DA0580 , a marine pennate diatom, contains extremely high levels of intracellular triglyceride and has been suggested as a promising source of feedstock for biodiesel fuels. JPCC DA0580 was isolated from a mangrove swamp located in S umiyo B ay below the mouths of the S umiyo and Y akugachi R ivers in A mami‐ O hshima, K agoshima, J apan. In this study, the morphology and the 18S rDNA sequence of JPCC DA0580 were compared with those of other F istulifera strains. JPCC DA0580 possesses morphological characters of the genus F istulifera , namely lightly silicified frustules, a distinct median costa (raphe sternum), and a wart‐like central pore (fistula). Morphometric analysis revealed that JPCC DA0580 differs from other F istulifera species by the presence of a valve with coarser striation and coarser areolation. On the basis of 18S rDNA phylogeny, JPCC DA0580 formed a well‐supported clade with other members of the F istulifera species complex, although the number of nucleotide substitutions was highest in JPCC DA0580 . Our results led us to propose the taxonomic name F istulifera solaris sp. nov. for JPCC DA0580 .