New records of naturalised and invasive cacti (Cactaceae) from Gran Canaria and Tenerife, Canary Islands, Spain

Recent field work in Gran Canaria and Tenerife (Canary Islands, Spain) yielded records for 30 alien taxa of Cactaceae that had not been reported before, either from the whole area, or from one of the islands. Out of these, 17 are considered locally naturalised and/or potentially invasive: Cylindropuntia bigelovii, C. fulgida, C. pallida, C. prolifera, C. tunicata, Echinocereus rigidissimus, Haageocereus kagenekii, Hylocereus triangularis, Opuntia basilaris, O. elatior, O. ficus-indica x O. tomentosa, O. macrocentra, O. microdasys, O. pilifera, Oreocereus pseudofossulatus, Tephrocactus articulatus and Trichocereus huascha. The same applies to a rather characteristic form of O. ficus-indica that sometimes is referred to as f. amyclaea (syn.: O. megacantha). The presence of Opuntia monacantha and O. robusta, two species with a dubious status in the Canary Islands, is confirmed. Ten further taxa are considered casuals, often relics of cultivation. All taxa are illustrated, and for the naturalised and/or potentially invasive taxa additional information is provided. Two new combinations are proposed for Cylindropuntia fulgida f. mamillata and Tephrocactus articulatus f. papyracanthus.