Abstract
Butia is a neotropical genus whose identification is based mostly on characters from external morphology, which are sometimes variable or inadequate for species differentiation. We aimed to verify if leaf anatomy of 18 Butia species brings new characters suitable for species identification and if it corroborates the phylogenetic relationship within the genus. Moreover, we propose an anatomical key to assist in species identification. Pinnae were collected and subjected to the usual techniques for light and scanning electron microscopies. The anatomical key was created with the aid of Xper2 software, based on the importance of characters to distinguish species according to the Jaccard index. All species have isobilateral mirrored mesophyll, amphistomatic leaves and secondary vascular bundles with sclerenchymatic sheath reinforcement connected to the hypodermis. Among the species studied, B. marmorii and B. matogrossensis showed exclusive characters. For the other species, up to five characters are sufficient for delimitation. Our anatomical key presents relevant characters that allow the identification of the recognized species of Butia. Reliable anatomical characters of easy observation, especially the raphides, are valuable in species distinction. Leaf anatomy, already used to support new taxa in related genera like Allagoptera and Syagrus, can also be useful to validate questionable Butia species and differentiate between similar species but do not reflect the proposed relationship between Butia species.
Highlights
In spite of its monophyly (Merrow et al 2009, 2015), Butia is morphologically highly diverse (Glassman 1970; Dransfield et al 2008; Noblick 2010, 2014), causing difficulties in species delimitation (Soares et al 2014) and considerable changes on the taxonomy of the genus
Samples of Butia archeri, B. campicola, B. capitata, B. catarinensis, B. eriospatha, B. exospadix, B. lallemantii, B. leiospatha, B. leptospatha, B. lepidotispatha, B. marmorii, B. matogrossensis, B. microspadix, B. paraguayensis, B. pubispatha, B. purpurascens e B. yatay were collected from specimens cultivated in the Botanic Garden of the Plantarum Institute, in Nova Odessa municipality, São Paulo State, Brazil
The broader sampling of Butia in the present study confirms the presence of many characters common to the genus, such as isobilateral mirrored mesophyll, amphistomatic leaves and vascular bundles with a sclerenchymatic sheath reinforcement connected to the hypodermis, as previously described (Tomlinson 1961; Tomlinson et al 2011)
Summary
In spite of its monophyly (Merrow et al 2009, 2015), Butia is morphologically highly diverse (Glassman 1970; Dransfield et al 2008; Noblick 2010, 2014), causing difficulties in species delimitation (Soares et al 2014) and considerable changes on the taxonomy of the genus. According to Noblick (2014), between 2004 and 2014, the number of accepted species included in the genus has risen from 9 to 24, and more species are expected to be described. There is no consensus regarding the present total number of species, some of them being still questionable according to Noblick (2014). The World Checklist of Selected Plant Families—WCSP—(2018) lists 22 species, while the Flora do Brasil 2020 (Heiden et al 2018) recognizes 19 species and two varieties occurring in Brazil
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