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Homollea Arènes (Rubiaceae, subfamily Ixoroideae, tribe Pavetteae) is a genus of shrubs and small trees endemic to western and northern Madagascar. The genus comprises five species occurring in dry deciduous forest, often in limestone areas. The five species are narrow endemics and their conservation status is either Endangered (4 species) or Critically Endangered (1 species). Homollea is characterized by few-flowered, pseudo-axillary, pedunculate inflorescences, well-developed calyces with the lobes much longer than the tube, laterally flattened seeds with a shallow, elongated to linear hilum and entire endosperm, ovules arising from the upper margin of the placenta, and, pollen grains with supratectal elements in the shape of microgemmae. Until now, three species were known and their descriptions are amended. Two further species, H. furtiva De Block sp. nov. and H. septentrionalis De Block sp. nov., are described as new for science. The five species are dealt with in detail: descriptions, distribution maps, conservation assessments, illustrations, lists of exsiccatae and an identification key are given.
The western Indian Ocean genus Paracephaelis is revised. Sixteen species are endemic to Madagascar, 12 of which are new for science: P. aristata sp. nov., P. bardotiae sp. nov., P. capitulifera sp. nov., P. gautieri sp. nov., P. grandifructa sp. nov., P. longipedicellata sp. nov., P. orientalis sp. nov., P. pauciflora sp. nov., P. ranirisonii sp. nov., P. russata sp. nov., P. sambavensis sp. nov., and P. seyrigii sp. nov. Paracephaelis trichantha occurs on the east coast of continental Africa and on the islands of the Aldabra Group. One other species is newly described from the Comoros, P. comorensis sp. nov. Paracephaelis is characterized by sessile inflorescences, pubescent inflorescence and flower parts, ovules arranged at the periphery of the placenta, laterally flattened seeds with entire endosperm and a shallow elongate hilum, and pollen with supratectal elements. Of the Malagasy endemics, five species are assessed as Critically Endangered with P. sambavensis sp. nov. possibly Extinct in the Wild, three are Endangered, four are Vulnerable, one is Near Threatened, and three are Least Concern. Outside Madagascar, P. trichantha and P. comorensis sp. nov. are assessed as Vulnerable.