Phytotaxa 405 (1): 015–026 https://www.mapress.com/j/pt/ Copyright © 2019 Magnolia Press Article PHYTOTAXA ISSN 1179-3155 (print edition) ISSN 1179-3163 (online edition) Accepted by Eric Gouda: 20 May 2019; published: 29 May 2019 https://doi.org/10.11646/phytotaxa.405.1.2 15 Tillandsia bandensis (Bromeliaceae): its lectotypification and a new subspecies from Uruguay ANDRÉS J. ROSSADO 1 , SABINA DONADÍO 2 & JOSÉ M. BONIFACINO 1,3 1 Laboratorio de Sistemática de Plantas Vasculares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay. E-mail: arossado@fcien.edu.uy 2 Instituto de Botánica Darwinion (CONICET-ANCEFN), San Isidro, Buenos Aires, Argentina. 3 Laboratorio de Botánica, Facultad de Agronomía, Universidad de la República, Montevideo, Uruguay. Abstract A new epilithic subspecies of Tillandsia bandensis (Bromeliaceae) is described based on the analysis of herbarium specimens as well as living plant material in the field and in cultivation. The new subspecies differs from the typical one mainly by its bigger and more lepidote reproductive structures. Detailed morphological descriptions for T. bandensis and its subspecies are provided, as well as images, illustrations and data on distribution, habitat, phenology and conservation status for the new subspecies here described. Lectotypes for T. bandensis, T. bandensis var. intermedia and T. recurvata var. majuscula are designated. Keywords: atmospheric plants, Diaphoranthema, Tillandsioideae Resumen Se describe una nueva subespecie epilítica de Tillandsia bandensis (Bromeliaceae) sobre la base de análisis de especímenes de herbario así como de material vivo en campo y bajo cultivo. La nueva subespecie difiere de la subespecie típica principalmente por sus estructuras reproductivas de mayor tamaño y de mayor pubescencia. Este trabajo incluye descripciones morfológicas detalladas de la especie y sus subespecies, e información sobre distribución, hábitat, fenología y estatus de conservación, así como imágenes e ilustraciones sobre la nueva subespecie aquí descrita. Se designan lectotipos para T. bandensis, T. bandensis var. intermedia y T. recurvata var. majuscula. Introduction Tillandsia Linnaeus (1753: 286) comprises 741 species and 151 infraspecific entities (Gouda et al. continuously updated) of mainly epiphytic and epilithic herbs, distributed from southern United States to central Argentina and central Chile (Smith & Downs 1977, Zizka et al. 2009, Barfuss et al. 2016, IBODA continuously updated). According to the phylogenetic study and the recent taxonomic revision of the subfamily Tillandsioideae by Barfuss et al. (2016), Tillandsia has been classified into seven subgenera and several species complexes. Tillandsia bandensis Baker (1887: 234) is a typically atmospheric species that was recently included (Donadío 2013, Granados et al. 2017) in Tillandsia subg. Diaphoranthema (Beer 1854: 349) Baker (1878: 236), a monophyletic group represented by ca. 30 xeromorphic species (Donadío 2013, Donadío et al. 2015, Barfuss et al. 2016). Tillandsia bandensis occurs mainly as an epiphyte in dry woods of Bolivia, Paraguay, Brazil, Argentina and Uruguay, and can be easily distinguished from the rest of the species in the genus by its distichously arranged leaves, conspicuous violet flowers (petals more than 4 mm wide) and floral bracts equal or slightly longer than the internodes. This species shows a relative low morphological variation throughout its distribution, and historically it has not presented significant taxonomic problems. Recently, Rossado (2018) reported new populations from Uruguay of Tillandsia bandensis that differ morphologically, geographically, and ecologically from the typical ones and correspond with a hitherto undescribed subspecies. In this sense, the aim of this work is to describe and illustrate a new subspecies of T. bandensis, providing