Relationships in the alpine Ranunculus haastii (Ranunculaceae) complex and recognition of R. piliferus and R. acraeus from southern New Zealand

Abstract

Growth habit, vegetative, floral characters, and molecular data support the recognition of Ranunculus haastii and R. piliferus at species rank, rather than as intraspecific taxa at the rank of subspecies. Therefore, R. piliferus is a new combination at species rank for plants previously known as R. haastii subsp. piliferus. R. acraeus is a new species distinguished from R. piliferus by its finely crenate leaf and bract margins, glabrous peduncle, and in having 6–7 sepals that are hairy on the abaxial surface and glabrous on the adaxial surface. R. piliferus occurs in northern Southland and South Otago and R. acraeus occurs in North Otago and South Canterbury. R. piliferus and R. acraeus grow in relatively stable alpine rock‐fields that comprise rock fractured into large, coarse, and angular blocks of differing sizes and shapes. R. haastii occurs in Canterbury and Marlborough where it grows on mobile fine‐grained scree in the alpine zone. Phylogenetic analyses of nrDNA ITS and cpDNA JSA sequence data provide support for the segregation of R. piliferus from R. haastii, and for the recognition of R. acraeus. R. piliferus forms a distinct genotype in both the ITS and JSA analyses. R. acraeus and one sample of R. haastii have a distinct JSA genotype, and R. acraeus and R. buchananii share a nine‐base‐pair indel. In the ITS analysis R. acraeus and most samples of R. grahamii share the same genotype, and along with R. haastii form a northern, alpine group of diverse genotypes.