The first ultrasculpture palynological analysis on Weberbauerella (Leguminosae – Papilionoideae): a contribution to the phylogenetics of the Dalbergia clade

Weberbauerella is a leguminous genus found growing in isolated populations along the Peruvian Lomas and the Andes, under extreme climatic conditions. We present the most complete pollen morphology and ultrasculpture descriptions for two out of three species of Weberbauerella, with the aim of helping clarify the systematic relationships within the Dalbergia clade. Light and scanning electron microscopy images are provided to illustrate the main differences between the analysed species. The 3-colporate aperture, reticulate ultrasculpture (nanoreticulate to microreticulate), is shared by the analysed species of Weberbauerella. The pollen grain aperture margo, operculum, endoaperture class and details of the sexine ultrasculpture were useful characters to distinguish the species in the genus. Since the phylogenetic data available for Weberbauerella is limited, the relationship between it and the other members of the Dalbergia clade remains inconclusive. However, pollen morphology provides an additional layer of support for the many conflicting phylogenetic relationships recovered so far. Future studies combining palynological, macro-morphological, and molecular data might shed much-needed light on this group.