A New and Minuscule Annual Species of Montia (Montiaceae) From Alpine Fens in Otago, New Zealand

Montia minuscula Heenan is recognised as a new species from alpine habitats in Otago, South Island, New Zealand. It is currently known from only two locations, one in the Old Man Range (Kopuwai Conservation Area) and another in The Remarkables. It grows in palustrine fens that are associated with groundwater seepage such as from snowmelt and snowbanks. The main associated species are bryophytes and wetland vascular plants. Montia minuscula is distinguished from the indigenous Montia fontana subsp. fontana by its short‐lived annual growth habit, diminutive stature, flowers with shorter pedicels, smaller petals, ovaries, stigmas, anthers and capsules, capsule with typically 1(–2) seed and smaller seeds with slightly tuberculate surface. At the Old Man Range site, M. minuscula and M. fontana subsp. fontana are sympatric. Using the New Zealand Threat Classification Manual, Montia minuscula is assessed as having a conservation status of Threatened, Nationally Critical.