Pitardia resurrected: A new member of subtribe Menthinae (Lamiaceae)

Abstract

Despite tremendous progress towards clarifying phylogenetic relationships within the mint family (Lamiaceae), uncertainty remains regarding relationships among some major clades as well as the proper placement of some genera. While researching the genus Nepeta, a species from northeastern Morocco, N. nepetoides, attracted our attention due to its distinct morphology relative to other species of Nepeta. To explore the systematic position of N. nepetoides, Bayesian and maximum likelihood analyses were conducted using chloroplast, nuclear ribosomal, and low-copy nuclear markers. For phylogenetic analyses, a total of 5 accessions and 49 samples were newly sequenced for this publication, with the remainder coming from previous studies. Results from all three gene regions suggest that N. nepetoides should not be treated within Nepeta, but instead recognized as a distinct genus, the resurrected Pitardia. In addition, Pitardia is not even in the same subtribe as Nepeta (Nepetinae), and instead should be considered as a member of the subtribe Menthinae, a group that includes most of the culinary spices (e.g., oregano, peppermint, thyme) from the mint family. Notably, all analyses point to Pitardia being sister to the rest of subtribe Menthinae. Furthermore, lectotypes are designated for P. nepetoides and P. caerulescens, the taxonomic status of Pitardia is reassessed, and an updated and extended morphological description of Pitardia is provided based on herbarium specimens and field observations.