A biogeographic review of Parahebe (Scrophulariaceae)

Distribution maps and notes are given for the 41 species of Parahebe sensu lato. The genus occurs in New Zealand, south-east Australia and New Guinea, with greatest diversity in New Zealand, especially in the Spenser Mountains region of South Island. A group of species with ciliate floral discs is found in north-east South Island, and also in eastern Papua New Guinea. This outer Australasian arc distribution is attributed to the group having originated before the break-up of Gondwana. Within New Zealand the P. calarractae complex shows disjunction along the Alpine Fault, a plate boundary of the transform type. The disjunction is attributed to massive lateral displacement on the Fault during Tertiary time pulling apart plant populations. Parahebe sect. Paniculatae is newly described. The following new combinations are made: Parahebe brevistylis, P. macrantha, P. macrantha var. brachyphylla, P. raoulii, P. r. subsp. maccaskillii, P. r. subsp. pentasepala, P. lavaudiana, P. hulkeana, P. nivea, P. arenaria, P. velutina, P. blakelyi, P. arcuata, P. derwentiana subsp. maideniana, P. d. subsp. homalodonta, P. d. subsp. anisodonta and P. d. subsp. subglauca.