Abstract
Eleven varieties of Tibouchina gracilis were indicated as synonyms of Chaetogastra gracilis in the most recent work on the taxonomy of the genus. However, field observations and a more detailed analysis of herbarium specimens, including the types, led us to the conclusion that two of these varieties represent a single new species. Chaetogastra cogniauxiana is endemic to Brazil, and differs from C. gracilis by the smaller size, 10–70 cm tall (versus 30–120 cm tall in C. gracilis), dendritic-setose to dendritic-strigose hypanthium and bracteoles (vs. dendritic-sericeous hypanthium and bracteoles), and smaller petals, 9.8–13.4 × 8.8–9.1 mm (vs. larger petals, 16.5–21.6 × 11.2–14.8 mm). In this article, we provide a complete description of C. cogniauxiana, and indicate the main morphological differences between C. cogniauxiana and the most closely related species. We also provide comments on taxonomy and phylogenetic relationships of this species, photos, illustrations, and a distribution map. This work is part of a monograph of the genus Chaetogastra in Brazil, which showed a great species richness and also the necessity of several taxonomic adjustments.
References
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