A synopsis of the multilocular species of Ixora (Rubiaceae) from Madagascar

Abstract

Two new Ixora species from Madagascar are described, Ixora lagenifructa and I. quadrilocularis. Ixora littoralis, previously positioned in the monospecific genus Thouarsiora, is newly named I. homolleae. These three species are characterized by 4-locular ovaries and fruits, 4-lobed stigmas, large fruits with thick walls and well-developed calyces. A fourth species, I. trimera, shows the same characters but its ovaries are 2-, 3-or 4-locular and its stigmas are 2-, 3-or 4-lobed. A dichotomous key, detailed descriptions and distribution maps are given for these four species, the only multilocular ones in Madagascar.

Monograph of the western Indian Ocean genus Paracephaelis (Rubiaceae – Pavetteae), with description of thirteen new species

“…(from 3 to 6 species; Ruhsam & Davis 2007), Gaertnera Lam. (from 26 to 42 species; Taylor et al 2014), and Ixora L. (from 17 to 32 species; De Block 2007, 2014a, 2014b.…”

Ixora kalehensis, a new Rubiaceae species from the Democratic Republic of the Congo

“…A majority of its c. 530 species (Davis et al 2009) occur in Asia and Oceania, but Ixora is also represented in South and Central America and in Africa. More than 85 species of Ixora occur in Africa, c. half of those in Madagascar (De Block 2007Block , 2008Block , 2014aBlock , 2014b, 37 in continental Africa ( De Block 1998) and six species in the Mascarenes and the Seychelles (Mouly et al 2009b). In continental Africa, Ixora is easily recognized by the following characters: petioles articulate; inflorescences terminal, with branching trichotomous, articulate and bracteolate; flowers narrowly tubular, 4-merous; aestivation contorted; stigma bilobed; ovary bilocular with a single ovule per locule; fruits drupaceous, containing two seeds; seeds hemispherical or hemi-ovoid with a large adaxial excavation (De Block 1998).…”

“…I. pudica Baker from Mauritius) or by being 3-7-locular with the stigma 3-7-lobed, and the seeds 3-7 per fruit and not hemispherical or hemi-ovoid in shape (e.g. I. quadrilocularis De Block from Madagascar and I. borboniae Mouly & B.Bremer, formerly known as Myonima obovata Lam., from Mauritius and Reunion) (Verdcourt 1983, De Block 2014a.…”