New Zealand isolates from snow of the widespread algal genus Raphidonema assigned to a single species

ABSTRACT

Filamentous snow algae in the green algal class Trebouxiophyceae have been historically attributed to at least three genera: Raphidonema Lagerh., Koliella Hindák, and Stichococcus Nägeli. Their separation has been based on filament length and dissociation, and the shape of the terminal cells. However, the strong morphological plasticity of this material has been known since at least the 1970s, and a recent revision placed almost all of the known strains isolated from snow and ice globally into three species of Raphidonema: R. catena Leya & Yakimovich, R. nivale Lagerh., and R. sempervirens Chodat. In addition to three previously sequenced strains from New Zealand, we recently established 11 strains from snow collected throughout the Southern Alps (Fiordland, Otago, Canterbury, and Westland). Sequence data from the rbcL gene and the ITS2 rRNA region placed all of these strains into the species Raphidonema sempervirens. Some biogeographic structure is evident in the rbcL data, with New Zealand strains of the main subclade robustly split from strains isolated from the Northern Hemisphere (Europe, Iceland, Svalbard, North America). The other subclade of R. sempervirens also includes some New Zealand strains, and this subclade could become recognised as a separate species with more data and analysis.

KEYWORDS:

• Biogeography
• identification
• New Zealand
• snow algae
• phylogenetic analysis
• Raphidonema sempervirens

Acknowledgements

We thank A. Monks (Manaaki Whenua – Landcare Research, Dunedin) for assistance in the field, Kāti Huirapa Rūnaka ki Puketeraki for engaging with us regarding collecting and DNA sequencing requirements for collections in Otago, and the New Zealand Department of Conservation for assistance with this engagement. Collecting from the conservation estate was granted under concession CA31615-OTH.

Disclosure statement

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

Additional information

Funding

PMN and AP were supported by Strategic Science Investment Fund Core funding for Crown Research Institutes from the Ministry of Business, Innovation and Employment’s Science and Innovation Group, New Zealand. RK was supported by Western Washington University for fieldwork in New Zealand.