Systematics, phylogeny, and morphology of Alcantarea (Bromeliaceae)

Author(s)

Leonardo de Melo Versieux

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2009-12-15

Examining board members

Maria das Graças Lapa Wanderley; Lucia Garcez Lohmann; Jose Rubens Pirani; George John Shepherd; Tânia Wendt

• Advisor: Maria das Graças Lapa Wanderley

Abstract

This thesis comprises the taxonomic revision, phylogeny, and morphology of the genus Alcantarea (E. Morren ex Mez) Harms, composed of rupiculous bromeliads endemic to eastern Brazil rock outcrops. An overall characterization of Bromeliaceae is presented initially then followed by the objectives and justification of the thesis, which is structured in chapters. Chapter 1 presents the morphological characterization and revision of the genus based in field, herbaria and bibliography. Species descriptions, identification key, map and taxa conservation statuses are presented. The highlight results of this chapter are that 26 species are recognized, five of them being new and described by the author during the project (A. martinellii Versieux & Wand., A. patriae Versieux & Wand., A. tortuosa Versieux & Wand., A. trepida Versieux & Wand., A. turgida Versieux & Wand.), four new synonyms are presented (A. brasiliana (L.B. Sm.) J.R. Grant, A. edmundoi (Leme) J.R. Grant, A. lurida Leme, A. mucilaginosa Leme), and one neotype is designated. Almost all taxa are illustrated in detail, and photographic plates are also presented. A large number of specimens were collected and incorporated in herbaria and a living-collection was built at the Instituto de Botânica. In spite of usually forming large populations in difficult to access places six taxa are threatened of extinction due to restricted occurrence areas and habitat loss. In addition, it was not possible to determine conservation statuses for six species due to data deficiency. In Chapter 2 the molecular phylogeny of Alcantarea is presented. Two chloroplast markers (trnK-rps16, trnC-petN), one low copy nuclear gene (Floricaula/Leafy), and also 20 nuclear microsatellites loci were employed. Results point to a well supported monophyly of Alcantarea, in both bayesian and parsimony analyses. In these analyses Alcantarea emerges as the sister genus of eastern Brazilian Vriesea. Floricaula/Leafy provides better resolution and is recommended for future studies within Bromeliaceae. Microsatellites delimit species groups with strong biogeographic correspondence and also suggest that hybridization is frequent , once individuals of the same species appear closely related to different species groups. In chapter 3, a species complex predominantly from Espírito Santo and eastern Minas Gerais States is delimited and named Alcantarea extensa complex and its status as a complex is supported by microsatellite analysis (Ch. 2). At least 10 taxa that show low floral and vegetative morphological variation and posses geographic proximity among populations are included in this complex. A new species and viviparous seeds in Alcantarea fruit are also described in this chapter. Leaf anatomical characterization for nine species of Alcantarea is presented in chapter 4. Several of the observed features contribute to the survival of Alcantarea in xeric environments (campo rupestre/inselbergs) as the thick-walled epidermis, abundant covering of epicuticular waxes, mechanic hypodermis, aquiferous parenchyma, narrow air-lacunae filled up with the spongy parenchyma, and stomata restricted to the abaxial surface. Data obtained in chapters 1, 2, and 4 provided evidence to keep Alcantarea as a distinct genus, independent from Vriesea. Molecular data indicate that it is a monophyletic and well supported group sister of Vriesea s.s. The taxonomic history; the morphological distinctiveness of the long, ligulate, spiraled and ephemeron petals; seeds with basal and apical appendages and semi-inferior ovary also support this segregation. In addition, diagnostic characters available for the recognition of Alcantarea and Vrisea united are inconsistent and based on sympleisiomorphies exclusively. It is also suggested that the anatomical features such as the extension of the aquiferous parenchyma, the shape of the air channels and the extensions of the fibers bundles that forms more salient nerves and the presence of more developed septal nectaries are additional useful features to separate both taxa. (AU)