A new epiphytic species of Impatiens (Balsaminaceae) from the Comoro Islands

Une espèce nouvelle d’ Impatiens des Comores (I. wibkeae) est décrite et illustrée. Elle diffère d’ I. auricoma Baill. par le port épiphytique, les sépales latéraux rouges et les fleurs généralement plus grandes. INTRODUCTION The Comoro Islands, in contrast to Madagascar (FISCHER & RAHELIVOLOLONA 2002), harbour only a few species of Impatiens.

Up to now, two species are known, i.e. Impatiens auricoma Baill. which is also widely distributed in cultivation and I. comorensis Baker (= I. macradenia Baill.), a very distinctive species whose lower sepal bears two filiform spurs 30 mm in length. Despite recent regional inventories, the latter species has not been collected since more than 50 years ago and might even be extinct. In submontane rainforest on Moheli, an epiphytic Impatiens was collected by Jean-Noël LABAT, which was first considered to represent I. auricoma.

The new material, however, differs from this taxon in many respects and represents a new species, which is described below. It is undoubtly related to I. auricoma and is part of a group of taxa that are restricted to Madagascar and the Comoros, characterized by having two short spurs on lower sepal. In Madagascar, I. bisaccata Warb. from Montagne d’Ambre and I. tuberosa H. Perrier from Montagne des Français near Antsiranana belong to this group.

The main differences between I. auricoma and the new species are listed in Table 1. FIG. 1. — Impatiens wibkeae Eb. Fisch. & Rahelivololona: A, habit; B, flower, lateral view; C, flower frontal view; D, lateral sepal; E -G, lower sepal and spur; H, dorsal petal; I, lateral united petals.

Labat et al. 3215 (P). TABLE 1. — Distinction between Impatiens wibkeae and I. auricoma. The study is based on herbarium material from P (acronyms according to HOLMGREN et al. 1990).

The terminology used for measuring floral parts and in the descriptions follows GREY-WILSON (1980) and FISCHER & RAHELIVOLOLONA (2002). Thus the arrangement of floral parts is described after resupination.