This is the first phylogenetic analysis of the Megamexican Bromeliaceae genus Hechtia and includes 82.6 % of the known taxa. We used plastid (ycf1, rpl32-trnL intergenic spacer), and nuclear (PRK) DNA regions, as well as morphological characters. We generated 244 new sequences for a total of 62 taxa (including 12 species of the outgroup). Results of combined data using parsimony and Bayesian inference reveal the monophyly of Hechtia, as well as identify five well supported clades: (1) a clade (H. tillandsioides complex) as the sister group to the rest of Hechtia; (2) a clade including the species of the H. guatemalensis complex, distributed in Southern Megamexico; the remaining taxa of the genus are retained in a clade which consists of three well-supported clades; (3) the H. glomerata complex distributed in the Gulf of Mexico drainage; (4) a clade of two species (H. deceptrix and H. epigyna) that share an inferior ovary and are distributed north of the Tehuantepec Isthmus in the Sierra Madre Oriental; and (5) an internally poorly resolved clade with the remaining species containing several well-supported, geographically restricted clades. At this time it is uncertain what part of Megamexico was first invaded by the ancestor of Hechtia. Regardless, it becomes clear that from the original point of invasion in what is now Megamexico, it radiated into restricted geographical realms with secondary radiations occurring within them, which resulted in some recurrent particular evolutionary trends most likely associated with the invasion of dry, highly seasonal climates, or cooler areas subject to occasional frosts. Lateral inflorescences and flower morphology suggesting pollination syndromes other than melittophily (psychophily/trochilophily) have evolved more than once in Hechtia.

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Background: Hechtioideae is a group of Bromeliaceae that is distributed in Megamexico III. In recent years, evolutionary relationships within this lineage have been studied, however, the biogeography of these plants have not yet been explored from a phylogenetic framework. The integration of geographic and phylogenetic information in the evolutionary study of organisms has facilitated the identification of patterns, as well as the exploration of new hypotheses that allow understanding the processes that have influenced the evolutionary history of lineages. Questions and/or Hypotheses: What is the biogeographic history of this lineage? How Hechtioideae has diversified over time? Results: The Neotropical region has the highest species richness of Hechtioideae and the Mexican Transition Zone is the area with the greatest phylogenetic diversity. This lineage presented its highest diversification rate during the late Miocene and Pleistocene (6.5-1 Ma). The ancestral area of the group corresponds to the Neotropical region and the Mexican Transition Zone. In addition, Hechtioideae spread across their current ranges through multiple dispersal events associated with climatic and geological events during the last 10 Ma. Conclusions: Hechtioideae is a group of recent origin whose evolutionary history has been strongly influenced by geological and climatic events over the past 10 Ma, such as the glacial and interglacial periods of the Pleistocene and the great tectonic and volcanic activity that led to the formation of the Trans-Mexican Volcanic Belt.

Androlepis najarroi (Bromelioideae, Bromeliaceae), a third dioecious species identified in the subfamily, is proposed as new from the Chiapas Highlands and Veracruzan biogeographical provinces, southern Megamexico. The novelty is superficially similar to Aechmea lueddemanniana but features characteristics of Androlepis, such as unisexual flowers and apically divided filaments. Based upon available information on the species and current generic concepts, assigning this species to Androlepis might only be provisional. The present contribution includes distribution maps, iconography, an identification key to the species of Androlepis, and a preliminary evaluation of the conservation status of this new species.

Bakerantha is one of the three genera of subfamily Hechtioideae (Bromeliaceae). This genus was reestablished recently, and it currently contains four species (B. caerulea, B. lundelliorum, B. purpusii, and B. tillandsioides), which are distributed throughout the central region of Mexico. Bakerantha tillandsioides has the widest geographical distribution of the four species, and some populations currently referred to it do not match the species description. In this study, we used extensive sampling (81 accessions) of four plastid regions (matK, rpl32-trnL, rps16-trnK, and ycf1) and the nuclear PRK gene to reconstruct the phylogenetic relationships and delimit the species boundaries in Bakerantha. Our results confirm the monophyly of Bakerantha, and the species delimitation analysis supports five evolutionary lineages within Bakerantha, showing that B. tillandsioides is nonmonophyletic as currently circumscribed. Diagnostic characters and coherent geographical distributions support the five lineages. On the basis of our results, we describe and illustrate B. hidalguense as a new species and provide evidence that B. caerulea is morphologically and ecologically different from B. tillandsioides, with which it has been confused in the past. Additionally, we provide a morphological key to the Bakerantha species.