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| Leucheria melorum Horton & Picca, in Horton & Picca, 2026. |
Abstract
A new species of Leucheria endemic to the Patagonian Andes in northern Neuquén, Argentina, is reported. Leucheria melorum is characterized by its cushion-like growth habit composed of dense woolly rosettes, rhizomes covered by persistent old leaves, and capitula with white to pink flower corollas. The species inhabits high-elevation volcanic environments (2550–2900 m a.s.l.) on the Domuyo and the Wayle massifs. We provide a detailed morphological description, illustrations highlighting the diagnostic morphological traits and a key for distinguishing L. melorum from related species. Based on the IUCN criteria and categories, a preliminary conservation status assessment is also given.
Eudicots, Flora Altoandina, Leucheria, Nassauvieae, Patagonia
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| A. General view of the habitat of Leucheria melorum on Cerro Wayle at 2900 m a.s.l. with the Volcán Tromen in the background; B. Several dense rosettes; C. Rosette with capitula at different developmental stages; D. Close-up view of some flowering capitula; E. Fruit; F. Photomicrograph of the cypsela surface showing characteristic twin trichomes (indicated by white arrows) and biseriate glandular trichomes (indicated by black arrows). Photos A, C, E & F: Pablo Picca; B & D: J. Felipe Horton. |
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| Leucheria melorum. A. Habit; B. Leaf, adaxial view; C. Scape and capitulum; D. Inner phyllary, dorsal view; E. Outer phyllary, dorsal view; F. Bract-like phyllary, dorsal view; G. Flower; H. Flower (ovary and pappus removed); I. Stamens; J. Fruit. Line drawings by Angélica Marino. |
Leucheria melorum Horton & Picca, sp. nov.
Diagnosis:—Leucheria melorum is morphologically similar to L. candidissima and L. millefolium, which are also present in the northern Neuquén volcanic massifs. However, the new species is readily distinguished by its compact, cushion-like growth habit. It further differs from both by having very short stems (vs. more or less elongated in L. candidissima and L. millefolium), flabelliform leaf blades (vs. lanceolate in L. candidissima and elliptic in L. millefolium) and by having bi- or tri-pinnatisect leaves with oblong segments closely approximated towards the apex (vs. pinnatisect with an elongate terminal lobe in L. candidissima and bi- or tri-pinnatisect with rhomboidal segments in L. millefolium; segments regularly distributed along the rachis in both species).
Etymology:—The specific epithet honors Mabel and Sergio MELO, a couple of dedicated naturalists, who were the first people to collect specimens of this new species. Their keen observations of the high Andean flora and kind cooperation were very important to the recognition of this novelty.
Juan Felipe HORTON and Pablo I. PICCA. 2026. A New Species of Leucheria (Nassauvieae, Asteraceae) from the Patagonian Andes. Phytotaxa. 774(3); 241-251. DOI: doi.org/10.11646/phytotaxa.774.3.4 [2026-09-17]
