Re-establishment of Aechmea laxiflora (Bromeliaceae, Bromelioideae) based on morphological and phylogenetic evidence, with notes on its geographical distribution

Abstract

Background: Previous phylogenetic analyses suggested that Aechmea bracteata is not a monophyletic species, being each variety an individual lineage within the Aechmea bracteata complex.
 Hypothesis: A phylogenetic analysis based on molecular data and a morphological analysis will provide evidence to support the taxonomic recognition of A. bracteata var. pacifica as a distinct species.
 Studies species: A. bracteata var. bracteata, A. bracteata var. pacifica and related species.
 Study site and dates: Mexico to Northern South America; 17 populations from Southeastern and Western Mexico. Analyses were performed between 2021 and 2023.
 Methods: A linear morphometric analysis was conducted with 85 herbarium specimens testing 28 quantitative and three qualitative variables. Potential diagnostic traits were reviewed in living specimens. A phylogenetic analysis was performed with two nDNA markers (ETS and g3pdh) and one cpDNA marker (trnL-F). A total of 373 records were projected into biogeographical provinces of the Neotropics.
 Results: The morphometric analysis allowed to separate each variety into a group, also, nine of the evaluated traits resulted statistically significant through a univariate analysis. Five additional diagnostic traits from the inflorescence and leaves were recognized. According to nDNA both taxa present reciprocal monophyly, however, cpDNA groups A. bracteata var. pacifica with Central American species, showcasing a potential hybrid origin. Geographically, the Sierra Madre del Sur acts as a barrier between both taxa.
 Conclusions: Due to the gathered evidence is possible to recognize A. bracteata var. pacifica as an endemic species to Mexico, reestablishing the basionym A. laxiflora.