Santos 2015 (Conference Paper) Alcantarea

Comparative pollen morphology between Alcantarea (E. Morren ex Mez) Harms and Vriesea Lindl (Bromeliaceae Juss)

Author(s):—V.L. Santos, Graças Lapa Wanderley Wanderley, L. Versieux, B.A. Moreira, M.A. Cruz-Barros, Vitorino & C.F. Luz in Benko-Iseppon, A.M.; Alves, M. & Louzada, R. (2015) An overview and abstracts of the First World Congress on Bromeliaceae Evolution. Rodriguésia 66(2): A1-A66.

Publication:— (2015).

Abstract:—In recent phylogenetic analyses based on plastid and nuclear genome sequences, the genus Alcantarea emergesas a well-supported monophyletic group and sister to a clade including eastern Brazil Vriesea species. However, discussions involving the taxonomic position of Alcantarea, either as an independent genus or as subgenus of a broadly circumscribed Vriesea are still under debate, as well as the delimitations of some complex species with the genus. In the present work we study the pollen morphology for species of Alcantarea and Vriesea,aiming to increase the data available for taxonomic decisions and searching for diagnostic characters that can contribute to the definition of these taxa. The following species were studied: Alcantarea acuminatifolia Leme, A. burle-marxii (Leme) J.R. Grant, A. extensa (L.B. Sm.) J.R. Grant, A. farneyi (Martinelli & A. Costa) J.R. Grant, A. geniculata (Wawra) J.R. Grant, A. glaziouana (Lem.) Leme, A. heloisae J.R. Grant, A. imperialis (Carrière) Harms, A. nahoumii (Leme) J.R. Grant, A. nevaresii Leme, A. nigripetala Leme & L. Kollmann, A. trepida Versieux & Wand., A. turgida Versieux & Wand., Vriesea cacuminis L.B. Sm., V. brusquensis Reitz, V. phillipocoburgi Wawra, V. gamba Wawra, V. pardalina Mez, V. pseudoatra Leme and V. simplex (Vell.) Beer. For the pollen analysis acetolysis was used. The pollen grains were measured under optical microscopy (LM) and photographed through LM and scanning electron microscopy (SEM). The data were analyzed statistically. Alcantarea pollen grains are monads, the faces proximal and distal configure heteropolarity; ellipsoidal in polar view; biconvex or plane-convex in equatorial view; of large size; monosulcate; bilaterally symmetrical; with a wide sulcus, as long as the major equatorial axis, with a ?Vriesea imperialis? margo (the diameter of the lumina decreased at the ends of the sulcus); with a reticulate heterobrochate exine (smooth simplicolumellate or duplicolumellate muri, narrow or wide, straight or curved,continuous or discontinuous muri); rounded or polyhedral lumina (in some species a narrower lumina occurs, surrounding the larger ones), psilolumina or lumina filled with bacula and pila. The diameters of the ?lumina? decreased at the ends of the pollen grains, which present microreticulate or sparsely perforated sexine, with equatorial calotas, where exine ornamentation is different. Sexine thicker than nexine. The pollen morphologyof Vriesea species was similar to that of Alcantarea species, which does not help in the species segregation through these characters. The monosulcate pattern was found in the four specimens analyzed of Alcantarea nahoumii, as well as in other species of Vriesea, however in this species heteromorphism was observed in the pollen grains, with extended sulcate aperture without calota and zona-aperture without calota, the latter never before described for Bromeliaceae.

Keywords:—Vrieseeae; Palynotaxonomy; Bromeliaceae.