Two new species of Commicarpus (Nyctaginaceae) from the Horn of Africa

The new species Commicarpus altus Thulin from central Somalia and C. ogadenensis Thulin from southeastern Ethiopia are described, illustrated and mapped. Both species are shrubs with succulent leaves and white flowers, and they have previously been treated as forms of the widespread and variable C. plumbagineus (Cav.) Standl. Commicarpus altus is found on gypseous or saline ground at elevations of 125-150 m a.s.l., whereas C. ogadenensis seems to be entirely confined to gypsum at 350-550 m a.s.l. Commicarpus altus differs from C. plumbagineus, apart from being a shrub with succulent leaves, by having a glabrous perianth and a joint on the pedicel well below the anthocarp. Commicarpus ogadenensis differs from both C. plumbagineus and C. altus by having five (versus three) stamens.