Abstract
Campbell Island is a subantarctic island 600 km south of Stewart Island, New Zealand. It is a raised portion of the much larger submerged microcontinent, the Campbell Plateau, which is estimated to have split from Gondwana, along with Zealandia, during the Cretaceous period. Recruitment and gene flow of terrestrial organisms with neighbouring landmasses and mainland New Zealand is minimal, excluding migratory seabirds. It has fragmented isolated populations, and unique selection pressures of the subantarctic increase the likelihood of speciation occurring on Campbell Island via allopatry.
A macromycete survey (macroscopic fungal fruiting bodies visible to the naked eye) was conducted on Campbell Island in 1979 and 1980, spanning 106 days. This collection, initially housed at the John T. Waterhouse Herbarium, University of New South Wales, in Sydney, Australia, was donated to the Otago Regional Herbarium (Department of Botany, University of Otago). Here, the macromycetes in this collection, to the knowledge of the Botany Department at the University of New South Wales and the original collectors, have never been analysed to determine their taxonomic identity until I began my Master's in 2023. A soil sample collection was also undertaken in 2007, and I extracted fungal ITS2 ASVs to also be taxonomically analysed.
Specimens in the collection were given official herbarium OTA numbers and photographed to preserve their original appearance (as they were found at the beginning of my thesis). Tissue samples from each specimen were excised, and DNA extraction, sequencing, and phylogenetic analysis were attempted in order to determine their taxonomic identification. Overall, 16 specimens in the sporocarp collection, belonging to genera Auricularia, Conocybe, Daldinia, Entoloma, Inocybe, Psilocybe, and Stereodiscus were phylogenetically analysed. Other sporocarp specimens were BLAST identified to the genera Hygrocybe, Hypholoma, Panaeolus, Pleurotus, Protostropharia, and Psathyrella. The soil data was also analysed, and revealed 45 additional taxa not previously recorded in the sporocarp collection, or any previous literature regarding macromycete diversity on Campbell Island. The taxonomic identities of the sporocarp specimens and soil ASVs were discussed, with six of the seven genera phylogenetically analysed not previously being recorded on Campbell Island, and four of the seven not being previously recorded within any of the subantarctic islands (Auckland Islands, Antipodes Islands, Bounty Islands, Macquarie Islands, Snares Islands) of the Campbell Plateau. Overall, of the 70 distinct fungal taxa identified from both the sporocarp and soil collection on Campbell Island, only 15 were previously recorded to inhabit Campbell Island, and 21 in the wider Campbell Plateau, making this analysis the largest current addition to the mycofloral diversity of both Campbell Island and all the Subantarctic Islands.