A new combination and taxonomic notes in Pseudobombax Dugand (Malvaceae)

Abstract Taxonomic notes in the Neotropical genus Pseudobombax (Malvaceae) are presented. One new combination and two new heterotypic synonyms for taxa originally described from Brazil and Ecuador are proposed based on both morphological and previously published molecular evidence. The taxonomic changes will be adopted in a treatment of Pseudobombax for the upcoming Brazilian Flora 2020 and in a forthcoming revision of the genus throughout its range.


Introduction
Field and herbarium studies of the Neotropical genus Pseudobombax Dugand (Malvaceae) along with previously published molecular phylogenetic studies (Carvalho-Sobrinho et al. 2016) revealed that taxonomic changes are needed in the genus. Nomenclatural changes are proposed herein for taxa that will be included in a monograph of Pseudobombax for Brazil (Carvalho-Sobrinho in prep.), which is being prepared for the upcoming Brazilian Flora 2020 (http://floradobrasil.jbrj.gov.br/). The changes also will be incorporated in a taxonomic revision of the genus throughout its range.

Methods
Taxonomic literature related to Pseudobombax was evaluated in order to check typifications and synonymies of taxa. Information about type specimens was derived from protologues and checked against major online nomenclatu ral indices (Tropicos -http://www. tropicos.org/; JSTOR Global Plantshttps://plants.jstor.org). Herbarium abbreviations follow Index Herbariorum (Thiers 2017). Type specimens that have been examined in person by the first author are followed by exclamation marks. When digital images were discovered online, a barcode number is given for the specimen followed by its source. Notes. Robyns (1963) proposed Pseudobombax grandiflorum var. majus based on specimens with longer pedicels and staminal tubes as well as wider calyces and petals than are found in the nominate variety. Analysis of the protologue and type material of this variety and the nominate one, along with a comprehensive examination of herbarium specimens, reveals that P. grandiflorum var. majus is also morphologically distinct from the nominate variety in having mostly 9-11 (vs. mostly 5) leaflets (7 leaflets rarely occur in both taxa), often 3-7-flowered cymes (vs. flowers solitary, rarely 2-3-flowered cymes), and 5-angulate (vs. 5-costate) fruits in cross-section. Moreover, P. grandiflorum var. majus has calyces that are urceolate (vs. cupuliform) and often lobed (vs. truncate).

Nomenclatural changes
In addition to these morphological differences, the two taxa can be distinguished by their distribution in Eastern Brazil. Pseudobombax grandiflorum var. majus inhabits semi-deciduous forests and occasionally granitic outcrops in wet forests whereas the nominate variety inhabits mainly coastal restinga vegetation. Thus, morphological evidence along with the parapatric distribution are sufficient to recognize Pseudobombax grandiflorum var. majus at species rank.
Pseudobombax majus can be distinguished from its sister species P. longiflorum (Mart.) A. Robyns (Carvalho-Sobrinho et al. 2016: fig. 2), a widespread species in South American savannas, by its cuneate (vs. truncate) leaflets, shorter (c. 10 vs. 16-50 mm long) petiolules, and its 5-angulate (vs. circular) fruits in cross-section. Notes. The characters (leaflet shape, calyx dimensions, and pubescence of staminal tubes) used by Robyns (1963) to segregate Pseudobombax guayasense are not sufficient to distinguish it from P. millei based on a more comprehensive sampling of herbarium collections. Previously, phylogenetic analyses of DNA sequences were interpreted as supporting the accessions examined of these two taxa as sister groups (Carvalho-Sobrinho et al. 2016: fig. 2), but we now consider P. guayasense to be a synonym of P. millei on the basis of combined morphological and molecular evidence. Notes. The characters (tree height and pubescence of staminal tubes) used by Robyns (1967) to segregate P. amapaense do not permit it to be distinguished from P. munguba based on a more comprehensive sampling in the field and in herbarium collections. Previously, phylogenetic analyses of DNA sequences were interpreted as supporting the accessions examined of these two taxa as sister groups (Carvalho-Sobrinho et al. 2016: fig. 2), but we now consider P. amapaense to be a synonym of P. munguba on the basis of combined morphological and molecular evidence.

Acknowledgments
Thanks are due to curators and staff of herbaria visited by JGCS and to the institutions that loaned specimens; the Department of Botany of the Smithsonian Institution, Washington, D.C. for a José Cuatrecasas Fellowship to JGCS; the Fundação de Amparo à Pesquisa do Estado da Bahia -FAPESB (process APP0006/2011) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico -CNPq (process 158916/2014-0) for financial support; and Frank Almeda for reviewing the manuscript. This paper is part of the PhD thesis of JGCS prepared in the Programa de Pós-Graduação em Botânica (PPGBot -UEFS) and supported by a grant from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -CAPES and a sandwich fellowship through the Reflora program (CAPES process BEX 5415/13-6).