The Identity of the Common East African Species of Craterispermum Benth. (Rubiaceae) with Some Other Notes on the Genus

Abstract

For many years it has been usual to call the common East African Craterispermum, C. laurinum (Poir.) Benth., which is the type species of the genus and described from West Africa; for example Dale (1951), Brenan (1954), Dale & Greenway (I954) and White (1962) all use this name and Hepper (1963) gives the distribution of C. laurinum as Senegal to Nigeria and 'also in Congo, Uganda, Kenya, Tanganyika, Nyasaland, N. & S. Rhodesia, Mozambique and Madagascar'. Nearly all the herbarium material from eastern and central Africa has been labelled C. laurinum, but C. laurinum differs from the eastern plant in having the fruits distinctly shortly pedicellate*, the peduncles longer, the inflorescences more often branched, the leaves blunter and the calyx limb mostly truncate. K. Schumann (1895) does not record C. laurinum from East Africa but gives the distribution of C. schweinfurthii Hiern as 'Io, II and 17' i.e. 'Sudan, Ghasal Quellengebiet, Sansibar and Seengebiet'. There is no doubt in my mind that all the material from eastern Africa formerly called C. laurinum is in fact C. schweinfurthii. Brenan (1949) also doubted the identity of the eastern plant which he mentioned 'does not satisfactorily match W. Afr. material' and merely called it C. sp. C. schweinfurthii and C. cerinanthum Hiern are closely allied and some Angolan specimens are difficult to place, but in general the latter has longer more slender peduncles bearing more slender often divided inflorescences and less coriaceous less reticulate often more acuminate leaves. C. schweinfurthii is by no means uniform, rather it is extremely variable. The type of the species (Sudan, Equatoria, [Niamniam], Khor Bodo, Schweinfurth 2935 (K, holotype)) is not a typical example of the species and has a peduncle about I cm. long, although other Schweinfurth specimens have much shorter peduncles, the range for the species being 2-1o mm. A specimen from Pemba I. (Ngezi Forest, 18 Feb. 1929, Greenway 1482) has a peduncle 9 mm. long and is from a remarkably low altitude for the species and, although Schumann records it from Zanzibar, the only other specimen I have seen from a low altitude is from Tanzania (Bagamoyo District: Bana Forest Reserve, 29 Oct. 1965, Mgaza 785). Towards the south of its range, C. schweinfurthii tends to have larger and more strongly reticulate leaves and such specimens match the type of C. reticulatum De Wild. Other specimens from Zaire have much