Four new species of ribes (Grossulariaceae), primarily from the amotapeHuancabamba zone in Northern Peru

Four new species of Ribes L. (Grossulariaceae) are described from Peru, three from the AmotapeHuancabamba Zone and one from the eastern slopes of the Andes in central Peru. Ribes chachapoyense Weigend & Breitkopf, R. tumerec Weigend & Breitkopf, and R. huancabambense Weigend & Breitkopf from the AmotapeHuancabamba Zone represent close allies of Ecuadorian species and underscore both the floristic connections of this region to Ecuador and its high levels of floristic distinctness and endemism. With these three new species, the species total for the Peruvian part of the AmotapeHuancabamba Zone now reaches 10, nearly half the species present in Peru. Ribes frankei Weigend & Breitkopf is possibly the most aberrant species of Ribesit is a small, cushion-forming dwarf-shrub to 30 cm tall, with erect inflorescences that are virtually immersed in the leafy cushions. It is the smallest species of Ribes known so far and has been collected on vertical rock faces in the high Andes of Pasco in central Peru. The species total for Peruvian Ribes now reaches 23, which is nearly twice the number of species known for any other individual South American country, indicating that Peru, and especially the AmotapeHuancabamba Zone, represents the center of diversity of the genus in South America. Three of the newly described species are already at the brink of extinction due to habitat destruction (overgrazing, burning, mining, forest clearing: R. tumerec, R. frankei, R. huancabambense) and have to be considered as Critically Endangered. The fourth species, R. chachapoyense, has a slightly wider range and can be considered as only Endangered according to IUCN Red List criteria.