Three new Melicytus species from central New Zealand and a revised circumscription of Melicytus obovatus (Violaceae)

Abstract

ABSTRACTFour shrub species, including three newly described, are recognised in the Melicytus obovatus complex from central New Zealand. The new species segregated from M. obovatus sens. str. are M. improcerus, M. orarius and M. venosus, and are recognised based on a morphological assessment of growth habit, leaf and floral characters following detailed herbarium, cultivation and field studies. Melicytus obovatus is recircumscribed to include dioecious shrubs with leaves that are usually elliptic-oblong and the petals have a prominent purple margin. It occurs on a range of calcareous substrates in northwest Nelson, from near sea level to 944 m elevation. Melicytus improcerus also occurs in northwest Nelson and is restricted to upper montane and subalpine zones between 800 and 1500 m elevation, predominantly on marble substrates. It has a low growing, compact growth habit, is dioecious, usually has leaves that are broadly elliptic-oblong, broadly elliptic or elliptic-oblong, and petals without a prominent purple margin. Melicytus orarius is a hermaphrodite shrub with obovate, broadly obovate or narrowly obovate leaves that have a distinctly retuse apex and the petals have a prominent purple margin. It is confined to coastal habitats in Cook Strait, and in the North Island is restricted to the Wellington region where it occurs from Kapiti Island in the west to the Wairarapa coast in the east, and in the South Island it occurs throughout the Marlborough Sounds. Melicytus venosus is only known to have female flowers and may be apomictic, and has broadly elliptic, broadly elliptic-oblong or ovate-orbicular leaves that have up to six teeth mostly in the distal half of the leaf margin. Its distribution is centred on the western Marlborough Sounds, with a disjunct population known from Kapiti Island. For each species, typification, description, distribution, habitats and illustrations are presented, along with an assessment of their conservation status.