Re-evaluation of the taxonomic status of Cyathea kermadecensis and C. milnei (Cyatheaceae) supports their continued recognition: Tuhinga 26

Tuhinga 26: 49-60

ABSTRACT: Two species of Cyathea (Cyatheaceae) have been recognised as endemic to Raoul Island in the Kermadec Islands: C. kermadecensis and C. milnei. However, their relationships to their mainland relatives – C. cunninghamii and C. dealbata, respectively – have been uncertain, with their morphological distinctiveness in question. Here, we review their taxonomic status. The DNA sequences investigated are uninformative as to delimitation of the Kermadec plants, but they do support a close relationship to the mainland species. Morphologically, we find that C. kermadecensis can be consistently distinguished from C. cunninghamii, and likewise C. milnei from C. dealbata. With no data to reassess whether species or subspecies rank is most appropriate, we recommend the taxonomically conservative approach of retaining both C. kermadecensis and C. milnei as separate species for now.

KEYWORDS: Cyatheaceae, Cyathea cunninghamii, Cyathea dealbata, Cyathea milnei, Cyathea kermadecensis, ferns, Kermadec Islands, New Zealand Botanical Region, taxonomy.