Taxonomic Delimitation of Species Complexes: A Challenge for Conservation; First Steps with the Abarema cochliacarpos Complex

Taxonomic and ecological knowledge of plant species complexes informs their conservation status. Poorly delimited species boundaries can lead to incorrect assessments of biodiversity, and a rare species might have its distribution range overestimated if considering other closely related taxa as the same one. The present study investigates the level of morphometric variation within the Abarema cochliacarpos complex throughout its entire distribution range in the Brazilian Atlantic Forest and Caatinga vegetation, and considers the drivers of this variation. A morphometric study using cluster, PERMANOVA, and NMDS analyses was conducted. We analyzed patterns of trait variation among and within populations, and their relationship with environmental factors along with their geographical gradient. From the four morphotypes previously cited for the complex, the analyses delimited three morphological groups. Their morphological characteristics differed in response to environmental drivers. We identified morphological characters that differentiated the groups within the complex. The development of conservation strategies and actions to fully protect a species complex requires the understanding of the morphological variation within the complex. In the Abarema cochliacarpos complex different threats and challenges are associated with the conservation of each morphotype. We highlight the importance of conserving the various morphotypes of a species complex which has a large distribution range as evolutionary significant units, something that is frequently neglected in the published literature.