Three New Species of Coffea L. (Rubiaceae) from Madagascar

Abstract

The three species described here are evergreen, in common with all other Coffea species from eastern Madagascar. In this paper we have used the term calyculus to describe the bract-like structures that occur immediately beneath the inflorescence branch(es) and/or pedicel(s). These structures are undoubtedly formed by the reduction of a vegetative shoot, where each calyculus is made up of a pair of reduced leaves and a pair of reduced stipules. Each Coffea inflorescence usually has three calyculi, and each calyculus is normally four-lobed. The four lobes are arranged in two pairs: the lobes derived from the stipules are here referred to as the stipular lobes, and the other set derived from the leaves are called the foliar lobes (see Figs 1 3). In common with other species of Coffea from Madagascar (excluding subgenus Baracoffea see below), the corolla tube of C. manombensis is longer than the corolla lobes. According to P. Stoffelen (pers. comm.) a corolla tube distinctly longer than the corolla lobes is absent in Coffea species from tropical Africa, although in a few species (e.g. C. liberica, C. congensis, C. kapakata and C. heterocalyx) the corolla tube can be sometimes slightly longer than the lobes. The length of the corolla tube relative to the lobes has been used in keys to separate Coffea from Psilanthus (e.g. Stoffelen 1998, p. 65), but it now seems that this character cannot be used successfully if species from Madagascar are included in identification keys. In species of Coffea subgenus Baracoffea, which occur in western Madagascar, the corolla tube is always much longer than the lobes.