Néstor Raigoza’s research while affiliated with Centro de Investigación Científica de Yucatán and other places

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.

Independent evolutionary lineages or species that lack phenotypic variation as an operative criterion for their delimitation are known as cryptic species. However, these have been delimited using other data sources and analysis. The aims of this study are: (1) to evaluate the divergence of the populations of the T. ionantha complex; and (2) to delimit the species using multilocus data, phylogenetic analysis and the coalescent model. Phylogenetic analyses, genetic diversity and population structure, and isolation by distance analysis were performed. A multispecies coalescent analysis to delimit the species was conducted. Phylogenetic analysis showed that T. ionantha is polyphyletic composed of eight evolutionary lineages. Haplotype distribution and genetic differentiation analysis detected strong population structure and high values of genetic differentiation among populations. The positive correlation between genetic differences with geographic distance indicate that the populations are evolving under the model of isolation by distance. The coalescent multispecies analysis performed with starBEAST supports the recognition of eight lineages as different species. Only three out of the eight species have morphological characters good enough to recognize them as different species, while five of them are cryptic species. Tillandsia scaposa and T. vanhyningii are corroborated as independent lineages, and T. ionantha var. stricta changed status to the species level.

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 for the 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 its 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.

Bakerantha is one of three genera of subfamily Hechtioideae (Bromeliaceae). This genus was reestablished recently, and 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 an 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 non‐monophyletic as currently circumscribed. Diagnostic characters and coherent geographical distributions support the five lineages. Based on 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. This article is protected by copyright. All rights reserved.

The most recent phylogenetic analyses using molecular and morphological data of Hechtioideae revealed the presence of three well-supported, morphologically distinct clades related to each other as follows: (Hechtia tillandsioides complex [Hechtia guatemalensis complex (Hechtia s.s.)]). (1) H. tillandsioides complex is recognized here at the generic level (under the reestablished name Bakerantha), characterized by its grass-like leaves, which are almost entire or minutely dentate, central inflorescences with pedicellate flowers, and papyraceous, pendent fruits; this clade includes four species confined to the Veracruzan, Sierra Madre Oriental, Balsas Basin, and Transmexican Volcanic Belt biotic provinces. (2) The H. guatemalensis complex, here proposed as the new genus Mesoamerantha, is characterized by the presence of central inflorescences and flowers with 3/4 superior ovaries and is confined to the Pacific Lowlands, Veracruzan, Mosquito, and Chiapas Highlands provinces (in Belize, Guatemala, Honduras, El Salvador, and Nicaragua). The remaining sampled taxa are grouped into a clade (3) that consists of three well-supported lineages: the Hechtia glomerata complex distributed in the drainage of the Gulf of Mexico; a clade conformed by two species (H. deceptrix and H. epigyna) from the Sierra Madre Oriental that share an inferior ovary, and a poorly resolved internal clade (Core Hechtia) with the remaining species containing several well-supported, geographically restricted clades.

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.