Abstract
The systematics of Notoacmea Iredale, 1915 have been confused because of their highly variable shells. We used DNA sequences from a mitochondrial gene (COI) and a nuclear gene (ITS1) to define the species boundaries among New Zealand Notoacmea species, using the allied genus Patelloida Quoy & Gaimard, 1834 as outgroup. Phylogenetic trees of 195 individuals showed 14 well-supported, reciprocally monophyletic clades, which we treat as species: N. badia Oliver, 1926, N. cellanoides Oliver, 1926, N. daedala (Suter, 1907), N. elongata (Quoy & Gaimard, 1834), N. parviconoidea (Suter, 1907), N. pileopsis (Quoy & Gaimard, 1834), N. scapha (Suter, 1907), N. scopulina Oliver, 1926, N. sturnus (Hombron & Jacquinot, 1841), N. subantarctica Oliver, 1926, Patelloida cortica (Hutton, 1880) and three new Notoacmea species, N. potae, N. rapida, and N. turbatrix, which are described here. Of the above names, N. daedala and N. subantarctica are resurrected from synonymy. Notoacmea helmsi (E.A. Smith, 1894) and N. virescens Oliver, 1926 are interpreted as synonyms of N. elongata.