A revision of Xylopia L. (Annonaceae): the species of Tropical Africa

A revision of the 45 species of the pantropical genus Xylopia in Tropical Africa includes descriptions of six new species and a new section of the genus. The fruits and seeds of Xylopia show specializations that promote vertebrate dispersal, primarily by hornbills and monkeys. Over half of the African species have an Area of Occupancy (AOO) less than 80 km(2), suggesting that they are in need of protection. African species are classified into five sections. Section Neoxylopia, with four species, is centered in the Guineo-Congolian Region and includes X. globosa sp. nov. Section Ancistropetala, with three species, occurs in the same region. Both of these sections are endemic to Africa. Section Xylopia, which extends to Madagascar and the American tropics, has only a single species in Africa, X. aethiopica. The three species of section Verdcourtia sect. nov. are restricted to the East African coast and Madagascar. The largest number of African species, (34) belong to section Stenoxylopia, in which the seeds lack the arils found in the other sections and instead have a fleshy sarcotesta. Section Stenoxylopia is divided into two informal groups, one centered in eastern and southern Africa (X. odoratissima group) and the other centered in the wetter forests of western and central Africa (X. acutiflom group). Five new species are described in section Stenoxylopia: Xylopia nilotica sp. nov. from Sudan, South Sudan, and Uganda, Xylopia calva sp. nov. from Nigeria and Cameroon, which is allied to X phloiodora, and Xylopia monticola sp. nov. from Nigeria and Cameroon, X piratae sp. nov. from Ivory Coast and Ghana, and X unguiculata sp. nov. from Gabon. The latter three species are segregates of the former Xylopia acutiflora s. I. One new combination is made at the species level, X shirensis comb. nov. Keys, descriptions, illustrations, distribution maps, and an index to numbered collections document diversity and assist with species identification. The name Unona oliveriana Baill. was found to pre-date the name Unona lepidota Oliv., requiring the combination Meiocarpidium oliverianum comb. nov.