A Revision of Stolzia (Orchidaceae)

Abstract

Stolzia was described by Schlechter in 1915 as a monotypic genus based on S. nyassana collected in the Bundali Hills at the northern end of Lake Nyasa [Lake Malaxai] by Adolf Stolz, a German missionary. The genus was characterized by an inflorescence terminal on a small pseudobulb as in Polystachya but distinct in having resupinate flowers similar to those of Bulbophyllum with an anther containing six pollinia. Collections in the Uluguru Mountains in east-central Tanzania by H. J. Schlieben led Mansfeld (1934) to describe a further three species and also to clarify certain generic features. He established that eight pollinia, four large and four small, rather than six were present and he also noted that the rostellum was almost quadrate. Summerhayes (I953) reviewed the genus and recognized a further group of four species centred on the area of the Ruwenzori and Virunga Mountains on the Zaire/Uganda border. He transferred three of these species from the genera Bulbophyllum (B. cupuligerum Kraenzl. and B. peperomioides Kraenzl.) and Polystachya (P. repens Rolfe) to Stolzia and described a fourth species, S. diffusa. Later, Summerhayes (1964) also transferred the West African Bulbophyllum elaidum Lindl. to Stolzia as its terminal inflorescence and flower structure fitted well with the characteristics of that genus. Summerhayes (1953) also commented on collections made by Mr. and Mrs. R. E. Moreau in the Uluguru Mountains of Tanzania, and was able to distinguish S. atrorubra Mansf., S. nyassana Schltr. and two probably new species. Recently, many additional collections have been made in Tanzania, Mala^ 'i and Rhodesia. Cribb (1977) described a new species S. compacta from the Nyika Plateau in Mala i and indicated its affinity to other collections from southern Mala^i and Rhodesia and from Tanzania. These