Descripción de Aeonium urbicum ssp. boreale (Crassulaceae), una nueva subespecie de uno de los endemismos más representativos de Tenerife, islas Canarias

Aeonium urbicum ssp. boreale, a new endemism of the most northern part of Tenerife Island, is described and illustrated. The morphological features of this new taxon allow its description in the rank of subspecies. A differential diagnosis with the other two known subspecies of A. urbicum, the ssp. urbicum of the northern side of Tenerife and the ssp. meridionale of the southern and southwestern part of the island, is done. Its area of distribution, the characteristics of its habitat and the state of conservation are specified. A table with the main diagnostic features that distinguish each subspecies of A. urbicum and a key for their identification are included. Type material is deposited in the herbariums TFC of the Universidad de La Laguna and TFMC/PV of the Museo de Ciencias Naturales de Tenerife.