Recognition of Pachystegia hesperiasp. nov. and notes on P. insignis, P. minorand P. rufa(Asteraceae: Astereae)

ABSTRACTFour shrub species, including the newly described Pachystegia hesperiaHeenan & Molloy, are recognised in PachystegiaCheeseman, a genus endemic to southern Marlborough and northern Canterbury, South Island, New Zealand. Pachystegia hesperiais distinguished by its compact and low statured growth habit, obovate to elliptic-oblong leaves with the adaxial surface reticulate with distinctive primary and secondary veins, a short peduncle and narrow capitula, smaller and fewer ray petals and fewer disc florets. It was previously known by the tagnames P. “B” or P. “Lowry”. Pachystegia hesperiahas a western and inland distribution comprising Lowry Peaks Range, Amuri Range, and southern parts of Inland and Seaward Kaikōura Ranges. The previously recognised P. insignis(Hook.f.) Cheeseman, P. minor(Cheeseman) Molloy and P. rufaMolloy are retained. Pachystegia insignishas the most widespread distribution and includes plants referred to the tagnames P. “A” or P. “Coast” and is naturally variable in leaf shape, capitula diameter and the presence and number of leafy bracts on the peduncle. Pachystegia minoris restricted to coastal and lowland habitats between Puhi Puhi and Waiau Toa / Clarence Rivers and includes plants from Ōhau Point (Marlborough) previously known by the tagname P. “C var. ii” or P. “Ōhau Point”. It is distinguished by rhomboid to obovate leaves, narrow capitula and in having the fewest florets. Pachystegia rufais distinguished by reddish trichomes on the leaves, stems and infloresences and has a restricted distribution in Haldon Hills, Marlborough. The widespread P. insignishybridises with P. minorand P. rufa. Typification, distribution, habitats and conservation status are presented for each species.