Selaginella P. Beauv. from Minas Gerais, Brazil

Acta Botanica Brasilica - 30(1): 60-77. January-March 2016. ©2016 doi: 10.1590/0102-33062015abb0247 Selaginella P. Beauv. from Minas Gerais, Brazil Gustavo Heringer1, Iván A. Valdespino2 and Alexandre Salino3* Received: September 21, 2015 Accepted: October 23, 2015 ABSTRACT Selaginella P. Beauv. is the only genus in the family Selaginellaceae Willk. The genus is monophyletic, has a cosmopolitan distribution, contains about 750 species and can be characterized by the presence of rhizophores, leaves, a ligule, heterospory and adaxial, reniform sporangia. Twenty species were found in the study area: Selaginella alstonii, S. contigua, S. convoluta, S. decomposita, S. erectifolia, S. erythropus, S. flexuosa, S. jungermannioides, S. macrostachya, S. marginata, S. microphylla, S. muscosa, S. producta, S. sellowii, S. sematophylla, S. suavis, S. sulcata, S. tenella, S. tenuissima and S. vestiens. Two new species records for the state are presented (S. jungermannioides and S. tenella). We present descriptions of the genus and species, an identification key, the synonyms pertaining to Brazil, illustrations, and comments about the taxonomy and distribution of species in Brazil. Keywords: Lycophytes, pteridophytes, Selaginellaceae, Southeastern Brazil, taxonomy Introduction Selaginella is the only genus in the family Selaginellaceae, has a fossil record that dates back from the late Carboniferous (Rowe 1988; Thomas 2005) and is placed in the division Lycopodiophyta (Pryer et al. 2001; Banks 2009). The family is clearly monophyletic and is sister to Isoetaceae (Korall et al. 1999; Pryer et al. 2001; Korall & Kenrick 2002; Pryer et al. 2004). The genus is characterized by the presence of rhizophores, leaves, a ligule, heterospory and adaxial, reniform sporangia (Webster 1992). The genus has a cosmopolitan distribution (Tryon & Tryon 1982; Jermy 1986; 1990) and comprises approximately 750 species (Góes-Neto et al. 2015), of which circa 270 species are found in the Americas (Tryon & Tryon 1982) and 61 occur in Brazil (Valdespino et al. 2015). Various works exist about the infrageneric classification of Selaginella (e. g. Spring 1849; Baker 1883; Walton & Alston 1938; Alston et al. 1981; Jermy 1986; 1990). The most recent classifications (Jermy 1986; 1990) divide Selaginella into five subgenera based on morphology and 1 geographic distribution. Since then phylogenetic studies based on molecular characters have suggested that some of these subgenera may not be monophyletic (Korall et al. 1999; Korall & Kenrick 2002). Furthermore, Korall & Kenrick (2004) as well as the previously mentioned studies have suggested the infrageneric division of Selaginella into two groups: one group representing S. selaginoides (subg. Selaginella) and another group, with the majority of the species, called the “rhizophoric clade” by Korall & Kenrick (2002). The main studies about species of Selaginella from Brazil are the following: Spring (1840), Fée (1869; 1873), Alston (1936), Alston et al. (1981); and in a reginal scale: Silveira (1898; 1908), Bautista (1974a; 1974b), Bautista et al. (1975), Castellani & Freitas (1992), Hirai & Prado (2000), Prado & Freitas (2005), Hirai (2007), and Prado & Hirai (2008). Still, new species have been recently described (Valdespino et al. 2015; Góes-Neto et al. 2015) and the new records in this work show that taxonomic and floristic studies can significantly increase our knowledge about the genus. Therefore, our objective in this study was to develop a taxonomic treatment of Selaginella for the state of Minas Gerais, Brazil. Departamento de Biologia Vegetal, Universidade Federal de Viçosa, P.H. Rolfs, 36570-900, Viçosa, MG, Brazil Departamento de Botánica, Facultad de Ciencias Naturales, Exactas y Tecnología, Universidad de Panamá, Apartado Postal 0824-00073, Panamá, Panama 3 Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, P.O. Box 486, 31270-901, Belo Horizonte, MG, Brazil * Corresponding author: 2 Selaginella P. Beauv. from Minas Gerais, Brazil Materials and methods The taxonomic study was based on samples collected by a team of pteridologists from UFMG, which were processed according to standard techniques and deposited at BHCB. In addition, herbarium specimens from Brazilian (CESJ, HUFU, OUPR, R, RB,, SP and SPF) and foreign herbaria (B, BM, C, F, K, NY and P) with important historial and type specimens, including digitized images, were studied. The herbarium abbreviations used in this work are based on Index Herbariorum (Thiers 2015). The genus description was based on Tryon & Tryon (1982), Tryon & Stolze (1994), Fraile et al. (1995) and Mickel et al. (2004). Species descriptions were based on selected material and field observations. Measurements of leaves were made following Valdespino et al. (2014), whereas those of stems diameter were taken below the first branch and of the width of terminal branches on sterile branches (including leaves). Spore color given are based on observation under a dissecting scope with an incident yellow light at 6.7-80.0 magnification and taking care that these were not contaminated by debris or fungi. The terms employed in this work are based on those used by Lellinger (2002), except for carinate (Stearn 1992) and isophyllous and anisophyllous (Mickel et al. 2004). Additionally, we prefer to follow Mital (1969) and Valdespino (1995) as explained in Valdespino et al. (2014) in terming leaves surfaces as “upper” (in lateral leaves = adaxial, while in median leaves = abaxial) and “lower” (in lateral leaves = abaxial, whereas in median leaves = adaxial). Moreover, to keep descriptions manageable, the presence of idioblasts and other projections on leaf surfaces is only mentioned for those species where they are found. We present the discrepant morphological measures between parentheses to highlight the exception. Results and discussion Selaginella P. Beauv., Mag. Encycl. 5: 478. 1804; and Prod. Fam. Aethéog. p. 101. 1805, nom. cons. Type: Selaginella spinosa P. Beauv. nom. nov. for Lycopodium selaginoides L. [ Selaginella selaginoides (L.) Link]. Plants terrestrial, rupicolous or rarely epiphytic. Stem thin, branched, sometimes dichotomously, prostrate, creeping, ascending or erect, usually arising from a stoloniferous base, with numerous leaves. Leaves isophyllous, generally imbricate or anisophyllous, alternating in four rows, two ventral and not appressed to the stem and two dorsally appressed, axillary leaves present on stem branches. Sporangia wide, originating in the axils of sporophylls. Megasporangia deltate-ovoid to lobed, usually containing four megaspores. Microsporangia ovoid, containing numerous microspores. Megaspores large (ca. 150-1500 μm), tetrahedral-globose, trilete, often with an equatorial flange, surface, regulate, reticulate, rugulatereticulate, papillate, tuberculate, granulate or seemingly smooth on the proximal surface. Microspores small (ca. 18-63 μm) (...truncated)