Aphelidium parallelum, sp. nov., a new aphelid parasitic on selenastracean green algae

ABSTRACT

Aphelids (phylum Aphelida = Aphelidiomycota) are intracellular parasitoids of algae and represent one of the early-diverging or sister lineages of the kingdom Fungi. Although aphelids are a small group comprising four genera and 17 species, molecular phylogenetic analyses revealed that numerous environmental DNA sequences represent undescribed lineages, indicating their hidden diversity. Here, we investigated a novel aphelid strain, KS114, that parasitizes selenastracean green algae. KS114 exhibited a life cycle typical of aphelids and produced posteriorly uniflagellate zoospores that resembled those of Aphelidium chlorococcorum f. majus in possessing a single apical filopodium but could be distinguished by ultrastructure features. In KS114, the kinetosome and nonflagellated centriole were aligned in parallel, a unique characteristic among the known aphelids. Kinetid-associated structures, such as fibrillar root and microtubules, were not found in the zoospores of KS114. In the molecular phylogeny of nuc 18S rDNA sequences, KS114 clustered with two environmental sequences and was distinct from all other sequenced species. Based on these results, we describe this aphelid as a new species, Aphelidium parallelum.

http://www.zoobank.org/urn:lsid:zoobank.org:act:3CB658DB-1F12-41EF-A57D-2CBFCDE6A49A

KEYWORDS:

• Aphelida
• Aphelidiomycota
• molecular phylogeny
• parasitoid
• ultrastructure
• 1 new taxon

ACKNOWLEDGMENTS

We thank the Microbial Culture Collection at the National Institute for Environmental Studies (MCC-NIES) for supplying selenastracean green algal strains and I. Suzuki (University of Tsukuba) for providing Monoraphidium sp. strain A11. We also thank the Sugadaira Research Station, Mountain Science Center, and the Open Facility Network Office, Research Facility Center for Science and Technology, University of Tsukuba, for the use of transmission electron microscope.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science (JSPS) Research Fellowships for Young Scientists (no. 202101228); the JSPS KAKENHI, a Grant-in-Aid for Scientific Research (nos. 19H03309, 19H05667); and the Next-Generation Energies for Tohoku Recovery (NET) Project from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.