Background:

Verbesina is the most diverse genus of the Asteraceae tribe Heliantheae. In the Sierra Madre Occidental, there are two richness areas where specimens related to Verbesina section Pterophyton were recently collected. These specimens do not correspond to any described taxon and are proposed as new species. Morphological and ecological traits between related taxa are compared, and maps, photographs, and an identification key are provided.

Questions:

Is it possible to recognize a greater diversity in the Verbesina section Pterophyton from populations studied in the Sierra Madre Occidental?

Species studied:

Verbesina section Pterophyton.

Study site and years:

Sierra Madre Occidental, 2016-2024.

Methods:

The study was based on field explorations and review of herbarium specimens. Distribution data and IUCN criteria were used to determine their conservation status.

Results:

Two new species are described. Verbesina bernalii is unique for developing winged peduncles and stems, opposite, entire, 3-lobed or hastate leaves concentrated towards the base of the stem, 1-2 capitula, fertile ray flowers, and 30-52 florets. Verbesina carrilloi belongs to the group with winged stems with entire peduncles but it differs by developing discoid capitula. Both taxa can be considered endangered.

Conclusions:

The new findings on Verbesina confirm some distribution patterns: Durango and Zacatecas, the municipality of Mezquital, Quercus and Pinus-Quercus forests, and the south of the Madrean, Tropical Madrean and Xerophilous Madrean ecoregions are richness centers. It is proposed that botanical explorations and collections of Verbesina be continued in the areas mentioned above, as more undescribed species may exist.

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