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| Waltheria marielleae T.S.Coutinho & M.Alves, in Coutinho, Sader, Pedrosa-Harand & Alves, 2022. |
Abstract
Background – Waltheria marielleae is a new species of Malvaceae endemic to north-eastern Brazil that occurs only in the states of Pernambuco and Alagoas, in areas of Atlantic Forest and Caatinga. It is characterized by cinereous leaves, axillary and sessile to subsessile inflorescences, pallid yellow corollas with apically eciliate petals and fan-plumose stigmas.
Material and methods – DNA was extracted from leaf tissue and the markers matK, ndhF, and ITS were amplified using universal primers, with PCR products purified and sequenced. Phylogenetic analysis was performed, including DNA sequences obtained from GenBank. Morphological studies were based on the analysis of specimens deposited in seven herbaria and specimens collected in Pernambuco state, Brazil.
Results – Waltheria marielleae is morphologically and phylogenetically related to pantropical W. indica and W. ackermanniana, with these three species forming a well-supported clade. Overall, phylogenetic molecular analysis suggests the monophyly of Waltheria, with the two currently proposed sections also being monophyletic, and Melochia as its sister group. The new species is assessed here as Endangered, according to IUCN criteria. In addition, we formally present new occurrences of W. ackermanniana and W. rotundifolia.
Conclusion – In this study, a complete morphological description, illustration, distribution map, and phylogenetic tree are provided for Waltheria marielleae. This species is compared with morphologically and phylogenetically related species (W. ackermanniana, W. indica, and W. rotundifolia) and an identification key to the species occurring in Alagoas and Pernambuco is provided.
Keywords: Alagoas, endangered species, endemism, fan-plumose stigmas, Hermannieae, Pernambuco, phylogenetic placement
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| Waltheria marielleae T.S.Coutinho & M.Alves, A. Flowering branch with detail of the trichomes. B. Bracteoles. C. Brevistylous flower. D. Longistylous flower. E. Calyx showing internal surface. F. Calyx lobe with trichomes removed showing veins. G. Petal (adaxial surface). H. Stamens and part of the gynoecium of a longistylous flower. I. Stamens and stigma of a brevistylous flower. J. Gynoecium of a brevistylous flower. K. Capsule. L. Seed. A, B, D–H from Coutinho et al. 375 (UFP, holotype); C, I–L from Coutinho et al. 376 (UFP, paratype). Drawn by Regina Carvalho. |
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| Waltheria marielleae (A–F), W. ackermanniana (G), W. indica (H), and W. rotundifolia (I). A. One population. B. General aspect showing greyish leaf indumentum. C. Detail of a flowering branch showing leaves and inflorescences arrangement. D. Stipule and inflorescence detail. E. Longistylous flowers showing the fan-plumose stigmas exserted. F. Brevistylous flowers showing stamens exserted. G. Detail of one inflorescence with a brevistylous flower. H. Inflorescence and detail of the homostylous flower. I. Inflorescence with brevistylous flowers. |
Waltheria marielleae T.S.Coutinho & M.Alves, sp. nov.
Diagnosis: Waltheria marielleae resembles W. indica by the branch indumentum, narrowly triangular stipules, elliptic leaf blades, axillary inflorescences, and fan-plumose stigmas, but differs by the olive green to greyish-green leaf blades (vs greenish), larger and distylous flowers (vs smaller and homostylous flowers), acute calyx lobe apex (vs acuminate), and spatulate and eciliate petals (vs oblong and ciliate).
Distribution and habitat: Waltheria marielleae is endemic to Brazil and known only from the states of Alagoas and Pernambuco (Fig. 4). This species is associated to the Atlantic Forest domain, found in seasonal semideciduous forests, as well as in the Caatinga (IBGE 2012), at elevations 300–700 m a.s.l.
Etymology: The specific epithet honours Marielle Franco, a sociologist and former Brazilian councilwoman who vehemently fought for social causes, including LGBTQI+ causes, a community that the first author is proud to be part of. Marielle Franco was cowardly murdered along with her driver Anderson Pedro Gomes in 2018, but her name remains alive in the memory of those who share her ideals.
Thales Silva Coutinho, Mariela Analía Sader, Andrea Pedrosa-Harand and Marccus Alves. 2022. Waltheria marielleae (Byttnerioideae, Malvaceae), A New Species from north-eastern Brazil supported by Morphological and Phylogenetic Evidence. Plant Ecology and Evolution. 155(3): 353-362. DOI: 10.5091/plecevo.94921
