A Note on the Type of Paxiodendron ulugurense (Monimiaceae)

Abstract

In tropical Africa the Monimiaceae are represented by two genera, Glossocalyx Benth. with four West African species, and Xymalos Baill. with one fairly widespread and variable species, X. monospora (Harv.) Warb. What appears to be one of the most unusual variants of X. monospora is that represented by the Kew isotype of Paxiodendron ulugurense Engl., which was reduced to synonymy by Verdcourt in Flora of Tropical East Africa, Monimiaceae (1968). This specimen was collected by Goetze (n. 274) in 1898 on the Lukwangule plateau of the Uluguru mountains, Tanzania, at an altitude of 2,400 m. Unfortunately this sheet consists only of fragments, and appears to be the only remaining material of this number; the holotype was destroyed in Berlin, and there is no other isotype at BR which has many of Goetze's collections (Bamps in litt.). The Kew material is remarkable in that, whilst the fruits are definitely those of a Xymalos, the leaves resemble those of Ocotea usambarensis Engl. As the fruits and leaves are separate on this sheet, it is quite possible that there has been a mix at some point, seeing that Ocotea usambarensis and Xymalos monospora grow together naturally. The Engler description mentions axillary racemes, so presumably the holotype consisted of more complete material than that sent to Kew, and it is almost certain that the specimen Engler described was a high altitude variant of Xymalos monospora with bullate leaves. However, in view of there being a possible mix in the Kew isotype, it is perhaps sensible to designate the fruits of the Kew sheet as the lectotype for Paxiodendron ulugurense, and ignore the leaves. It can now sink more conformably into Xymalos monospora.