A Revision of the African Species of Aerangis (Orchidaceae)

Abstract

H. G. Reichenbach proposed the genus Aerangis, in 1865, with a very brief description. He distinguished it from Angraecum by the long slender rostellum, and by the long stipes of the pollinia. Only two specimens were mentioned at the time: the type, from Angola, was named A.flabellifolia, and the other, from Ethiopia, a plant already described as Dendrobium? brachycarpum by A. Richard in 1850, was noted as probably belonging to Aerangis. It was formally transferred to this genus by Durand and Schinz in 1892. Both before and after this date Reichenbach's name was largely neglected and several other generic names were used for African orchids that are now known to be members of the genus Aerangis. Most species of white-flowered epiphytes from Africa were described originally in the genus Angraecum Bory. In 1888, Ridley proposed the name Radinocion for a single species from the island of Sao Tome that he thought was near to, but distinct from Angraecum. In 1891, in his Revisio Generum Plantarum, O. Kuntze transferred a number of species from Angraecum, under which name they had been described by various authors, to the genus Angorchis Thouars (1809). Garay (1973) and Friis & Rasmussen (1975) have shown that the name Angorchis is illegitimate; it cannot, therefore, be used for any of the species that were transferred to it in 1891, including several that are now placed in the genus Aerangis. R. A. Rolfe produced the first major account of the African orchids, in 1897, in the Flora of Tropical Africa. He ignored Aerangis, transferred the two species recognized by Durand and Schinz to Angraecum, and recorded only two other genera in the tribe Vandeae, viz. Listrostachys and Mystacidium. In 1907, Finet proposed the name Rhaphidorhynchus for various species of angraecoid orchids, including five of the African species of Aerangis that had previously been described under the genus Angraecum. Most of the names referred to above were reduced to synonymy by Rudolf Schlechter when he reorganized the African angraecoid genera in 1918. His paper must be referred to in this introduction on two counts. Firstly, in his classification, Schlechter recognized two main groups of genera that were stated to differ from one another depending on the presence or absence of a foot to the column. Within each group he again had one major division, depending on whether the rostellum is elongated, as in Aerangis, or not