A Conspectus of Polysphaeria (Rubiaceae)

Abstract

Polysphaeria was described by J. D. Hooker (in Benth. & Hook., Gen. P1. 2: 108 (1873)) who stated 'species 2 v. 3 Africae orientalis tropicae et ins. Comoro incolae'. At that date no species had been described; Hiern (Fl. Trop. Afr. 3: 127 (1877)) described four species and Brenan (Kew Bull. 4: 86 (1949)) has already selected P. lanceolata Hiern as lectotype species of the genus. Vatke (in Linnaea 40: 193 (1876)) had already described a P. ligustriflora based on two syntypes, Schimper 1110 & 1471 from Ethiopia. The Index Kewensis refers this name to Olinia cymosa and Hiern (loc. cit.) states 'belongs to the genus Olinia'. Despite this, Cufodontis (Enum. P1l. Aethiop.: 1005 (1965)) states 'Hiern 1877 hanc plantem ad Oliniam retulit, sed e bona descriptione sine dubio ad Rubiaceas referenda. Ulterius exacte comparanda'. Fortunately isosyntypes are preserved at Kew and without doubt belong to Olinia rochetiana. Cufodontis' statement is somewhat surprising since he had made a special study of Olinia. Further names were added by K. Schumann (1895, neriifolia) (1903, arbuscula, macrophylla, pedunculata), S. Moore (1906, zombensis), Krause (1907, squarrosa) (1912, brevifolia) (1920, braunii) and Good (1926, parviflora). Brenan (Kew Bull. 4: 81-6 (1949)) described two new species and made comments on the genus including a division into sections and series; a new variety was also published in 1954 (Mem. New York Bot. Gard. 8: 451-2) and further comments made. Cavaco (Adansonia II, 8: 379-82 (1968)) transferred to Polysphaeria four species formerly described by Baillon in Cremaspora in 1876-9 (congesta, grandis, maxima and tubulosa) and also described two new species (grandiflora and ovata). Under the name P. congesta he has cited material which I prefer to treat under five different species. Two other names have been published, neither of which has any standing. P. jubensis Chiov. (Fl. Somal. 2: 242 (1932)) is a nomen eventuale and P. lagosensis A. Cheval. was first mentioned as a name (Expl. Bot. Afr. Occ. Frang. 1: 328 (1920)) and later in the synonymy of P. arbuscula (Rev. Bot. Appliq. 18: 418 (1938)). Hooker placed the genus in the tribe Alberteae and was followed in this by Hiern and most workers, including Cavaco. Bremekamp, however, noted the Alberteae were heterogeneous, some genera having the ixoroid type of pollination mechanism and others not; those having it were transferred to a new tribe Cremasporeae. Later, Bull. Jard. Bot. Brux. 28: 252 (1958), I reduced this to a subtribe of Ixoreae, i.e. Coffeeae. Morphologically Polysphaeria is closely similar to Cremaspora and Tricalysia but they differ in stamens and lack of seed rumination. It is unquestionably closest to Lamprothamnus Hiern, the highly characteristic testa sculpture and rumination being the same in both.