Leaf venation reveals its potential for the taxonomy of Hyptidendron Harley (Lamiaceae - Hyptidinae) and supports the recognition of a new species, Hyptidendron cerradoense

Abstract

Leaf venation has not been widely used in taxonomic integrative works, although some potential in delimiting taxa has been reported. Hyptidendron, a neotropical genus with 20 species, seemed to present some variation in leaf venation patterns, which we sought to further investigate. A number of different herbaria were consulted, and herborized leaves were diaphanized for 20 species of Hyptidendron and a set of unidentified material. The taxa were classified according to their venation patterns. Hyptidendron possesses pinnate semicraspedodromous venation with reticulate irregular tertiary, quaternary and quinternary veins. Freely Ending Veinlets show some variation between species but without clear taxonomic importance. Otherwise, perimarginal veins were greatly informative, being present only in the unidentified material. Together with differences from other species of the genus in leaf shape, margins shape, calyx indumentum and petiole size, we hypothesize the unidentified material as a new species: Hyptidendron cerradoense, described here. We provide a full description, illustration, a distribution map, a preliminary conservation assessment and comments on both the taxonomy and ecology of the new species. Our study supports the importance of leaf venation for taxonomic studies, even in smaller genera.