Molecular Phylogenetic Analysis Corroborates the Species Status of <i>Comarostaphylis macvaughii</i> as Distinct from <i>C. discolor</i> Subsp <i>. discolor</i> (Ericaceae: Arbutoideae)

Abstract— Comarostaphylis is an endemic genus to North America, with a geographical distribution ranging from California to Panama. Ten species of Comarostaphylis are recognized, seven of which are endemic to Mexico. Comarostaphylis discolor comprises four subspecies, including C. discolor subsp. macvaughii , a perennial dwarf shrub endemic to isolated populations in the mountains near Tapalpa, Jalisco, Mexico. Based only on a morphology study, this subspecies was elevated to species rank but not recognized by some authors. In this study, we tested the taxonomic rank hypothesis of this subspecies using morphological data as well as molecular data within a phylogenetic framework. A total of 38 accessions of the internal transcribed spacer (ITS) were included in the analysis: three as the ingroup and 35 as the outgroup. Six new individuals were analyzed, three belonging to Comarostaphylis macvaughii and the other three to C. discolor subsp. discolor , all from the same locality. We performed maximum likelihood (ML) analyses using RAxML. Our phylogenetic results support the recognition of C. macvaughii as a monophyletic lineage, sister to the clade comprising C. arbutoides and C. discolor species. Additionally, our preliminary conservation status assessment indicates that it is a critically endangered species.