Romero 2017 (Dissertation) Hechtia
Sistemática y filogenia de los complejos Hechtia guatemalensis Mez y Hechtia tillandsioides (André) L.B. Sm. (Hechtioideae: Bromeliaceae)
Author(s):—K.J. Romero S.
Publication:— (2017).
Abstract:—The Megamexican genus Hechtia is composed of several species complexes, two of which are remarkable for their morphological, ecological, and biogeographical characteristics, namely, the H. guatemalensis spp.-complex and the H. tillandsioides spp.-complex. The first is composed entirely of three described extra-Mexican species (ranging from Guatemala in northern Nicaragua) whereas the second comprises four formally described taxa restricted to the Gulf Drainage in central México, north of the Tehuantepec Isthmus. The main goals of this project are to test the following hypotheses: Due to their intrinsic morphological features and geographically coherent distribution, both species complexes are monophyletic entities; based upon its distinctive morphology, the H. guatemalensis spp.-complex is sister to the remaining of the genus; and because most Hechtia species feature narrow ecological and geographical ranges, we predict that the few members of the genus that have been circumscribed as widely ranging and morphologically variable, will be composed of several, more narrowly distributed and circumscribed (cryptic) taxa. To test these hypotheses, extensive field work was carried out. Then, we analyzed cladistically 23 structural characters as well as sequence information from several regions of plastid (matK-trnK, rpl32-trnL+ indels, fragments 4 & 6 of ycf1) and nuclear DNA (the PRK region). The analysis included 69 terminals, accounting for all the ingroup taxa (from several populations per species) and 41 Hechtia spp. and 11 representatives of six subfamilies as outgroups. The several data matrices were analyzed separately as well an in combination under Maximum Parsimony and Bayesian Inference. The analyses recovered three strongly supported clades, one composed of all outgroup Hechtia spp. and one each for the H. guatemalensis and H. tillandsioides species complexes; however, the position of these clades within Hechtioideae was not resolved. On account of their morphological distinctiveness and biogeographical coherence, here we propose to treat each of the ingroup clades as distinct genera. The name Bakerantha L.B. Sm. is available for the H. tillandsioides species complex, which is readily diagnosed by leaves with serrulate margins, central inflorescences bearing hundreds of flowers on thin pedicels, narrow, papyraceous petals and sepals, superior ovaries developing into recurved capsules; this clade is composed probably by five species-level taxa restricted to Mexico, one of which is yet to be formally proposed. The H. guatemalensis species complex, composed of three species-level taxa, is defined by its soft, slightly succulent leaves, non-pungent spines, sessile, epigynous flowers, loculicidal, erect to pendent capsules. The taxonomic treatment includes keys to the species, pertinent iconography, discussions of affinities and conservation assessments for each species in both complexes.
Pages: 159
Published names (1):Hechtia guatemalensis