Between extinction and uncertainty: Nomenclature revision of genus Dalea L. (Papilionoideae, Fabaceae) in Cajamarca, Peru

Dalea L. is the only genus from the Amorpheae tribe distributed in the Peruvian Andes, where most of its species are endemic and endangered. The centre of diversity is within northern and central Andes mountain ranges converging with the Huancabamba Depression, a hotspot for cryptic plant diversity located in Cajamarca. Despite taxonomic studies conducted 40 years ago, morphological delimitations remain ambiguous due to phenotypic plasticity and the lack of type specimens, particularly among endemic taxa. This study aimed to assess morphological differentiation and carry out a nomenclatural revision of Dalea L. (13 species and 8 varieties) from the Cajamarcan Andes. As a result, we identifies 16 species in Cajamarca, based on distinctive morphological characters, including in stipule type; leaflet shape, pubescence density and number; inflorescence type; bract morphology; length of calyx distal tooth relative to its tube; number of glands per intercostal margin of the calyx; and fruit morphology. Nomenclatural changes were proposed for certain infraspecific taxa through their elevation to species rank, establishing: D. sericophylla Ulbr., D. cutervoana Szyszyl. and D. microphylla Kunth. The remainig varieties were reduced to synonymy under their respective species. Additionally, lectotypifications were carried out for the species D. myriadenia Ulbr., D. sericophylla Ulbr. and D. weberbaueri Ulbr., due to the loss of their holotypes which had been deposited at the Berlin Herbarium.