Geographic distribution, morphological diversity and conservation status of chascolytrum parodianum (Poaceae, Pooideae, Poeae) : an endemic species of Pampa Biome?

Abstract

Chascolytrum parodianum has been considered a rare species, endemic to Pampa Biome, only known for Uruguay and Southern Rio Grande do Sul, Brazil. The species was included as Critically Endangered (CR) in the national and regional Red Lists in Brazil. However, records of specimens morphologically similar to C. parodianum assigned as C. aff parodianum in the highland grasslands of Atlantic Forest Biome suggested an expansion on its distribution. In this study we aimed to test the morphological boundaries among known populations from both Biomes, including the variance of selected characters and their correlation with altitude. Through morphometric approaches, we generated box-plots comparing the variation of characters and analyzed the clustering of individuals using Hierarchical Cluster (HCA) and Principal Component (PCA) analyses. We also applied Mantel test for an ecological approach concerning altitude influence among populations. The results confirmed the occurrence of the species in Atlantic Forest Biome, whereas no character assessed showed considerable differentiation to support the circumscription of distinct taxa, confirming the inclusion of the specimens identified as C. aff. parodianum under the circumscription of C. parodianum. Mantel test did not show a significant correlation, but a tendency for altitude influence was found. A map showing the actual known distribution for C. parodianum is presented, as well as a reevaluation of its conservation status from CR to Vulnerable (VU). Future studies using niche modeling and phylogeographic techniques are needed to understand the evolutionary history and distribution of the species, since its actual range reveals disjoined populations under different abiotic conditions.