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| Asclepias gordaensis L.O. Alvarado & S. Islas, in Alvarado-Cárdenas et Islas-Hernández, 2024. |
Abstract
Background and Aims: Asclepias is a highly diverse genus within Apocynaceae, with 78 species in Mexico, being the most diverse taxon of the family in the country. Due to its complex morphology and similarities in floral characters, some taxa have been misidentified. In the present work, a new species is described for the genus.
Methods: Individuals were collected in the Sierra Gorda that could not be assigned to known species. National and foreign herbaria, digital databases, and specialized literature were reviewed to compare the collected specimens with similar species. Field expeditions were conducted in 2018 and 2023 to collect and monitor the phenology of the species of interest. The cohesive species concept was proposed as an explanatory hypothesis for the recognition of the taxa treated here. The conservation status was assigned following the IUCN criteria.
Results: A new species of Asclepias is described, known from the states of Guanajuato and Querétaro, distributed in pine, oak, and cloud forests. It differs from similar species by its gynostegial corona with bell-shaped hoods of rounded base, and linear to linear-lanceolate cornicles emerging from the base of the hood. Photographic plates, a distribution map, and a comparative plate between similar species are included, as well as a dichotomous key with similar species and those distributed in the states of Guanajuato and Querétaro. Based on its reduced distribution area and impacted habitat, it is considered a species at risk according to IUCN criteria.
Conclusions: In Mexico, Asclepias includes 79 species, reaffirming the country as a center of diversity for the genus. The new species forms a morphologically complex group with the species compared here, so it has gone unnoticed and been identified erroneously. The detailed review of morphology allowed suggesting these plants as a hypothesis of a species different from the rest.
Keywords: Asclepiadeae, endemism, gynostegial corona, horns
Asclepias gordaensis L.O. Alvarado & S. Islas sp. nov.
Asclepias gordaensis is morphologically similar to Asclepias pringlei (Greenm.) Woodson by its flowers less than 1 cm long and the presence or absence of horns, but is distinguished by its gynostegial corona with rounded-base campanulate hoods (vs. sagittate-appearing, truncate-based hoods in A. pringlei), linear to linear-lanceolate horns larger than the hood (vs. subacicular without exceeding the hood) arising from the base of the hood (vs. arising from the middle or top of the hood).
Leonardo O. Alvarado-Cárdenas and Carla Sofía Islas-Hernández. 2024. A New Asclepias (Apocynaceae, Asclepiadoideae) from the Sierra Gorda, Guanajuato-Querétaro, México. Acta Botanica Mexicana. 131; DOI: doi.org/10.21829/abm131.2024.2338
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