A Synopsis of Sloanea ( Elaeocarpaceae ) in the Neotropical extra – Amazonian Region

Th e genus Sloanea is comprised of 150 species, of which about 50 occur in Brazil among several vegetation types but mainly the Amazon and Atlantic forests. Th e present work provides a synopsis of the Neotropical species of Sloanea in the extra–Amazonian region based on a recent revision of the genus. In general, morphologically Sloanea comprises large trees endowed with buttressed roots; simple leaves; fl owers with sepals that may or may not cover the reproductive organs in pre–anthesis phases; stamens with the connective prolonged into an awn that is acuminate, acute or aristate and fruit covered with rigid or fl exible bristles or sometimes unarmed. Th is synopsis describes 17 species, and provides an identifi cation key, illustrations and comments on their diagnostic characters, geographical distribution and main bibliographic references.


Introduction
Sloanea, the largest genus of the family Elaeocarpaceae, contains about 150 species distributed in Australia, Asia, Madagascar, South America, Central America and Mexico (Steyermark 1952;1978;1988;Smith 1954;1965;1967;1996 In Brazil, the genus can be found throughout the country but particularly in more humid and preserved forest formations.Th e main contributions to the genus for the Neotropics were the taxonomic treatments published by Schumann (1886) and Smith (1954).Th e latter proposed the division of Sloanea into two subgenera and four sections (Subgenus Sloanea: Sections Sloanea and Brevispicae; Subgenus Quadrisepala: Sections Paniculi and Corymbo-racemi), based on the number of sepals and the position of the calyx in the fl oral bud, the persistence of the stipules and the type and position of the infl orescence.In this work, the infra-generic classifi cation proposed by Smith (1954) is recognized in part because we consider that the position of the calyx in relation to the bud is a good taxonomic character for the recognition of subgen.Sloanea (calyx not covering essential organs in the bud) and subgen.Quadrisepala (calyx covering the essential organs in the bud).Th e other characters used by Smith (1954) were not considered because of their overlapping distribution among the two subgenera and the four sections (Sampaio & Souza 2011a).
Th is synopsis is derived from a recent revision of the genus for the Neotropical extra-Amazon region (Sampaio 2009) and aims to contribute to the identification of recognized species by providing an identifi cation key and diagnostic morphological characters, illustrations and current geographic distribution.

Materials and methods
This work is the result of a review and analysis of collections and nomenclatural types available in 55 Brazilian and foreign herbaria cited throughout the paper, whose acronyms follow Holmgren & Holmgren (1998).Field expeditions were conducted in the following Brazilian states: Amazonas, Bahia, Espírito Santo, Goiás, Minas Gerais, Rio de Janeiro, Santa Catarina, São Paulo and Paraná.Collected material was deposited in the following herbaria: Escola Superior de Agricultura "Luiz de Queiroz", University of São Paulo (ESA) and University of Campinas (UEC).
Dimensions of vegetative and reproductive structures presented in the descriptions were measured from dried herbarium material (except for floral structures, which were rehydrated prior to measurement).Information concerning habit, flower coloration and other floral structures were obtained from data provided in the labels of herbarium material and, when possible, from in situ observations.
The morphological terminology used for vegetative and reproductive structures was based on Smith (1954), which is the standard for the genus, and Radford et al. (1976).The venation pattern of leaves followed the classification of Hickey (1979), and the terminology used for inflorescences was adapted from Weberling (1989).Abbreviations for the works cited in this study were based on Stafleu & Cowan (1981), whereas those of authors of genera and species followed Brummitt & Powell (1992).
According to Sampaio & Souza (2011a), the genus Sloanea can be recognized by the size of the tree (2 to 35 meters high), single leaves with swelling at both ends of the petiole, monochlamydeous flowers and fruits covered by flexible bristles.However, as exceptions, some species are of smaller adult size, such as S. hirsuta; have dichlamydeous flowers, such as S. petalata, or have glabrous and unarmed fruits, such as S. floribunda.
Neotropical species of the genus Sloanea are characterized by having simple leaves with alternate or opposite insertions, distributed along the branches or concentrated at the apex.In contrast, Coode (1983) noted that Sloanea sogorensis, an Old World species (New Guinea), has compound young leaves.Several juvenile individuals of species of Sloanea were observed during field expeditions for this work, but none exhibited compound leaves.Another important characteristic of Sloanea sogorensis, is the presence of a pair of stipules lateral to the petiole.In extra-Amazonian species the stipules may fall prematurely, and so these structures can be seen more easily in young branches.Some species have persistent stipules that remain until the maturation of the branches, but they soon fall (S.garckeana, S. lasiocoma, S. hirsuta, S. pubescens, S. retusa, S. terniflora, S. hatschbachii, S. uniflora, S. filiformis and S. fasciculata).In extra-Amazonian species stipules vary in size (from 1.5 -9 mm length) and shape (lanceolate, filiform or ovate).
The most important diagnostic characteristics used to differentiate species of Sloanea are the type of inflorescence, the position of the sepals in the bud, the shape of the anther connective extension and, to a lesser extent, the arrangement and structure of the bristles on the capsule.
In the extra-Amazonian region, flowers of Sloanea are monochlamydeous with only the calyx present.They are formed by one or two whorls of sepals (S. lasiocoma) with variable shape and size.The presence of sepals covering (Fig. 1A) or not the reproductive organs in the bud (Fig. 1B) is another useful taxonomic character.Likewise, the anther connective extension is an important character and is used to circumscribe many species of the genus.In this work, the genus was divided into three informal groups (acuminate, aristate and acute) based on the length and shape of the anther connective extension (Fig. 2).
The acuminate extension of S. guianensis, Sloanea hatschbachii, S. subsessilis and S. terniflora is about 1 mm long, and emerges from the anther maintaining constant width towards the apex (Fig. 2A-D).In other species, the extension of the aristate connective varies between 2 and 4 mm in length and arises abruptly from the anther, tapering towards the apex.Among the species with these characteristics are: S. garckeana, S. filiformis, S. floribunda, S. petalata and S. uniflora (Fig. 2E-I).The acute connective extension is less than or equal to 0.5 mm in length in S.eichleri, S.fasciculata, S. lasiocoma, S. hirsuta, S. obtusifolia and S. retusa (Fig. 2J-O).
The gynoecium also possesses characters useful for the delimitation of species of Sloanea (Fig. 3).The shape, size and, especially, type of indument covering the ovaries are used to separate some groups of species: S. garckeana and S. petalata, for example, have the ovary covered with a long-velutinous indument with branched hairs (Fig. 3H-I).This type of indument does not occur in other species of the extra-Amazonian region, and although branched hairs are also common in S. uniflora and S. terniflora, the type of indument covering the ovaries in these species is of the short-pubescent type (Fig. 3G, J).
The style, whose length varies between 1.5 and 8 mm, is also important for circumscribing some species of Sloanea.Sloanea eichleri, S. hatschbachii and S. filiformis, for example, have styles of 6 to 8 mm, the largest among extra-Amazonian species (Fig. 3K, N-O).Styles can be straight or twisted; however, since this is a highly variable character, it was not used for diagnosing taxa.The apex of styles can be whole, divided only at the apex or entirely divided throughout their length.In some species (e.g., S. floribunda, S. garckeana, S. petalata, S. terniflora and S. uniflora) the apex of the style is always entire (Fig. 3A, G-J), while in S. filiformis the style is deeply divided (Fig. 3N).
The fruits of species of Sloanea are loculicidal, woody capsules covered by an indument, which varies widely, and ornamented with stiff or flexible bristles, or is unarmed.Although the fruits, in general, are not good diagnostic characters, they may help in the recognition of some species.For example, in S. uniflora the bristles overlaying fruits are variable in length and indument, and may be an irritant, whereas in other species, such as S. floribunda, bristles may be completely absent.long.Seeds 1, ca. 5 x 3 mm, elliptical, aril not visible.
Geographical distribution: Sloanea uniflora occurs in gallery forests, often at waterlogged sites or close to watercourses in the Brazilian states of Mato Grosso, Mato Grosso do Sul and Goiás.