First insular population of the critically endangered Cistus heterophyllus subsp. carthaginensis on Cabrera Archipelago National Park (Balearic Islands, Spain)

Cistus heterophyllus subsp. carthaginensis is considered one of the most endangered plants of Spain and has been object to many conservation programs and research projects. Until now, only two small spots were located in Europe: a population of one self-incompatible specimen was found in Valencia and another small population in Cartagena, disturbed by human impact and hybridization with close-relatives. Therefore, the conservation of this taxon has been one of the most defeating issues in the current plant conservation strategies of the Mediterranean workgroups. In this study, we report, describe and cense a new population of this taxon located at the furthest accessible area of the isle of Cabrera Gran in Cabrera Archipelago National Park. The population contains 59 individuals of C. heterophyllus subsp. carthaginensis , the most abundant known population of this species, with a high representation of young individuals (83%). However, some threats are currently compromising the stability of this population: the presence of Cistus albidus in surrounding areas is producing hybrids ( Cistus × clausonii) and the high abundance of rats and rabbits is affecting the population recruitment. For this reason, urgent conservation actions must be designed to protect and enhance this population. Overall, this new finding offers new insights on the distribution and conservation strategies of this species.