Cyphostemma calcarium (Vitaceae), a new species from Ankarana Special Reserve, Madagascar

Cyphostemma calcarium is herein described as a new species on the limestone outcrops in northern Madagascar. Its diagnostic morphological characteristics were compared to the species occurring in Ankarana Special Reserve. We present detailed descriptions, illustrations, distribution map, and a preliminary conservation assessment of the species. An identification key to all known species from Ankarana Special Reserve is also provided.