Novelties in Selaginella (Selaginellaceae – Lycopodiophyta), with emphasis on Brazilian species

Abstract In this paper, I describe five new species of Selaginella from Brazil (Selaginella nanuzae, Selaginella neospringiana, Selaginella pellucidopunctata, Selaginella stomatoloma, and Selaginella trygonoides), compare them to morphologically similar species, and provide a preliminary conservation status assessment for each. The new species are illustrated with scanning electron photomicrographs of stem sections, leaves, and spores, when available. Also discussed in this paper are ten species, mainly from Brazil and with new distribution records, and the forthcoming resurrection of three species also occurring in Brazil. Three further non-native and presumed naturalized species are recognized in Brazil, and publication of one additional taxon is planned. Eighty-six Selaginella species are now known from Brazil and, of these, 80 are native (including 26 / 32.5%, endemic), and six are introduced. Brazil and Mexico have the second highest number of native Selaginella species in the Neotropics after Venezuela, which is estimated to have about 100. Of the newly documented species, Selaginella cabrerensis is now known to occur in French Guiana, Brazil, and Bolivia, in addition to Colombia, and Selaginella arroyoana and Selaginella chiquitana are synonymized under it. Likewise, Selaginella potaroensis is also recorded from Costa Rica and Brazil, and Selaginella seemannii from Panama and Brazil. Finally, leaf marginal stomata are reported on the newly described species and their functionality is discussed under Selaginella stomatoloma.


Introduction
In a recent paper, Valdespino et al. (2015) described seven new species of Selaginella from Brazil, raising the number of the known native species of that country to 58, and suggested that additional ones could be uncovered as further work in this genus continued. Th at prediction has proven accurate: Valdespino (2015a) has proposed S. boomii Valdespino, a new species widely distributed in South America, including Brazil. In addition, Goés-Neto et al. (2015) described S. salinoi Goés-Neto & G. Heringer, and Valdespino (2015b) published, S. monticola Valdespino. Th ese two species are restricted to Brazil. As part of my revisionary work on Brazilian Selaginella initiated in 1992, studying collections in R and RB, I now describe fi ve additional new heteromorphic species from Brazil: S. nanuzae Valdespino, S. neospringiana Valdespino, S. pellucidopunctata Valdespino, S. stomatoloma Valdespino, and S. trygonoides Valdespino. Moreover, 10 species are now recorded or confi rmed for the fi rst time mainly for that country: S. beitelii A.R. Sm., S. cabrerensis Hieron., S. falcata (P. Beauv.) Spring, S. lechleri Hieron., S. microdonta A.C. Sm., S. potaroensis Jenman, S. seemannii Baker, S. umbrosa Lem. ex Hieron., S. vernicosa Baker, and S. wurdackii Alston. Another species previously known to occur in Venezuela and just recently recognized in Brazil, included in Table 1 as Selaginella sp. A, will be described in the near future (Valdespino in prep.). Th ree species previously recorded from Brazil (i.e., S. chromatophylla Silveira, S. deltoides A. Braun [see also Valdespino in press], and S. glazioviana Hieron. [see discussion under S. trygonoides]), which were placed in synonymy by other authors (e.g., Alston et al. 1981), are in the midst of being reinstated in a separate paper (Valdespino, in prep.). Th ree non-native species are  Spring, and S. willdenowii (Desv.) Baker. Of the newly recorded species, S. cabrerensis (with updated synonymy), S. potaroensis, and S. seemannii are also documented for other neotropical countries. Th e novelties reported here increase the number of Selaginella species in Brazil to 86 (see Table 1), of which 80 are native and six are introduced and presumed naturalized. Among the native species, 26 are endemic (see taxa with an asterisk in Table 1). Th ese statistics represent an increase of 44% and 35% in the number of Selaginella species recorded in Brazil over previous accounts by Alston et al. (1981) and , respectively, and also increases the percentage of estimated endemic species from 27.2% (Prado and Hirai 2014) to 32.5%. After Venezuela, which is estimated to have ca. 100 species (Valdespino in press), Brazil (Table 1) and Mexico also with 80 native species (Mickel et al. 2004) have the second highest diversity of Selaginella in the Neotropics. With these new data, and based on information by Prado and Hirai (2014) for Brazilian lycophytes and ferns diversity, Selaginella is now the third most diverse genus and twelfth in endemism for that country.

Material and methods
Th is study is based on examination of herbarium specimens from AAU , B, BHCB, BM,  BR, C, CAS, COL, CR, E, F, G, GH, IAN, INPA, K, L, M, MG, MICH, MO, NY, OXF, P, PMA, RB, R, S, U, UC, UFP, US, W, and digitized images from B, BM, C, P, and UC (herbarium acronyms follow Th iers 2015). Further digitized Selaginella specimens from Brazil were consulted from RB (JBRJ 2015), Refl ora (2015), and Species Link (2015) virtual herbaria. Additionally, stem sections and spore samples from selected specimens were viewed with Scanning Electron Microscope (SEM) to determine upper and lower surfaces of leaves and spore sculpturing patterns and diameter (when available). Th e SEM study and measurement of leaves was conducted following Valdespino et al. (2014Valdespino et al. ( , 2015. Spore sculpturing and leaf terminology follow Valdespino et al. (2015 and references therein). Th e raw SEM images were processed with Adobe Photoshop to make the background black, adjust brightness and contrast, and for assembly in multipart fi gures according to species. Figures are provided only for new species, although additional SEM digitized images were taken for comparison from some other species discussed. Species descriptions are given only for new taxa and follow the order of characters and states used by Valdespino et al. (2015 and references therein). Entries for taxa newly recorded for Brazil and other countries are provided only for native species in a concise form, as most will be dealt with in separate papers, while non-native and yet unpublished ones are documented within Table 1 with herbarium vouchers examined or published references. Unique identifi er numbers (usually barcode numbers) in square brackets were provided for type specimens when available.
Conservation statuses were assessed for only new taxa and follow the IUCN Red list Categories and Criteria version 3.1, second edition (IUCN 2012).
Habitat and distribution. Selaginella nanuzae grows in dense premontane wet forests at 450 m in Atlantic forest vegetation. It is known only along the trail to Morro Corcovado in Parque Estadual da Serra do Mar, São Paulo.

Etymology.
Th is species is named for Professor, Dra. Nanuza Luiza de Menezes, an outstanding Brazilian botanist, who has been instrumental in advancing botanical and conservation sciences in her country and, in the course of her career, has mentored new generations of botanists at the University of São Paulo. Th rough her involvement with the Latin American Botanical Association, in 1992, I attended a plant morphology and anatomy course with emphases in taxonomy and evolution at that University; this led to my fi rst exposure to, and study of, Brazilian Selaginella.
Conservation status. Selaginella nanuzae was collected in a state park, where it may be adequately conserved. Nevertheless, given that there is large visitation along the trails of this park, particularly to ascend to Morro Corcovado where the only two known collections of the new taxa were made, and that some degree of deforestation occurs there, it is considered Vulnerable (VU).
Additional specimen examined ( Th e two specimens cited here under Selaginella nanuzae were previously determined as S. contigua, which as currently circumscribed is a morphologically variable species needing additional study. Selaginella nanuzae diff ers from typical S. contigua, as lectotypifi ed by Hirai and Prado (2000), by the characters given in the diagnosis. Selaginella nanuzae further diff ers from S. contigua by its ovate-oblong or ovate (vs. oblong) lateral leaves with the apices acute (vs. truncate or broadly obtuse), and ovate or ovate-lanceolate (vs. ovate-lanceolate) axillary leaves with rounded bases (vs. rounded to cordate). In addition, S. nanuzae has strongly imbricate leaves, while S. contigua has leaves that are usually distant. Diagnosis. Selaginella neoespringiana diff ers from S. vestiens Baker by the median leaves elliptic (vs. ovate or ovate-lanceolate), each 0.6-0.8 × 0.3-0.45 mm (vs. 0.9-2.0 × 0.4-1.0 mm) with bases rounded (vs. bases truncate or with the inner bases truncate and the outer bases auriculate or bases oblique), hyaline margins 10-30 μm (vs. 100-180 μm) wide and long-ciliate (vs. dentate to short-ciliate), each cilia 80-180 μm (vs. 40-50 μm), the lateral leaves ovate to ovate-elliptic (vs. ovate-deltate) with the upper surfaces glabrous (vs. with submarginal prickle-or tooth-like projections along basiscopic halves), the basiscopic margins entire on proximal ⅔ and denticulate along distal ⅓ (vs. dentate throughout), and sporophylls short-ciliate (vs. dentate). Description. Plants terrestrial (or epipetric?). Stems ascending to erect, stramineous, 3-5 cm long, 0.05-0.1 mm diam., non-articulate, fl agelliform on branches, stoloniferous, 1-or 2-branched. Rhizophores axillary, borne on proximal ¼ of stems, fi liform, 0.05 mm diam. Leaves heteromorphic throughout, membranaceous, both surfaces glabrous, upper surfaces green, lower surfaces silvery green. Lateral leaves spreading or slightly ascending, ovate to ovate-elliptic, 1.0-1.4 × 0.5-0.7 mm; bases rounded, acroscopic bases overlapping stems, basiscopic bases free from stems; acroscopic margins hyaline (more conspicuously so on lower surfaces), in a band 2-8 cells wide with the cells elongate, straight-walled and papillate parallel to margins, papillae in 1 or 2 rows over each cell lumen, long-ciliate throughout, basiscopic margins greenish or slightly hyaline in a band 1 or 2 cells wide with the cells rectangular, straight to sinuate-walled and papillate parallel to margins, papillae in 1-3 rows, long-ciliate throughout; apices cuspidate to short-acuminate, cusps 0.05 mm, variously tipped by 1-3 cilia; upper surfaces comprising quadrangular or rounded, sinuate-walled cells, many of these covered by 4-17 papillae, without idioblasts and with stomata along margins, lower surfaces comprising elongate, sinuate-walled cells, with few of these papillate and idioblast-like on both sides of the midribs, papillae in 2 rows over each cell lumen, with stomata in 2 rows along midribs. Median leaves distant, ascending, elliptic, 0.6-0.8 × 0.3-0.45 mm; bases rounded; margins hyaline in a band 2-6 cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in 1 or 2 rows over each cell lumen, long-ciliate throughout; apices long-aristate, each arista 0.1-0.3 mm, denticulate distally on upper surfaces, tipped by 1 or 2 teeth; both surfaces without idioblasts, upper surfaces comprising quadrangular or rounded, sinuatewalled cells, many of these covered by 2-17 papillae, with stomata in 1 row along distal ¾ of the midribs and some along proximal ¼ of outer margins, lower surfaces comprising elongate, sinuate-walled cells, without stomata. Axillary leaves similar to lateral  leaves. Strobili terminal on branch tips, quadrangular, 1.0-1.2 mm. Sporophylls monomorphic or the ventral ones slightly shorter, ascending, without a laminar fl ap, each with a slightly developed and glabrous keel along midribs, ovate to ovate-lanceolate, 0.7-1.2 × 0.5-0.8 mm; bases rounded; margins hyaline (this more obviously so on dorsal sporophylls), short-ciliate; apices acuminate to short-aristate, each acumen (arista) 0.05-0.1 mm, tipped by 1 or 2 teeth; dorsal sporophylls with upper surfaces green and cells as in median leaves, except for the half that overlaps the ventral sporophylls where the surfaces are hyaline with elongate, papillate, and slightly sinuate-walled cells, lower surfaces silvery green and comprising elongate, sinuate-walled cells; ventral sporophylls with both surfaces hyaline, comprising elongate, sinuate-walled cells. Megasporangia in 2 ventral rows; megaspores yellow, rugulate-reticulate on proximal faces with a slightly developed equatorial fl ange and perforate microstructure, reticulate on distal faces with echinulate and perforate microstructure ( Habitat and distribution. Selaginella neospringiana is known only from the type collection made in Morro de Cubiçado, Petrópolis, Brazil. No information on the label exists as to its habitat, but in this region Campos de Altitude (highland fi elds or high-altitude fi elds) vegetation is common. Th e type collection was probably made at or around the peak of the Morro at ca. 1650 m and has some mosses associated with it; thus, Selaginella neospringiana may be terrestrial or epipetric.

Selaginella neospringiana
Etymology. Th e specifi c epithet honors Anton Friedrich Spring (1814-1872), a German physician and botanist who is the author of the only worldwide monograph of Selaginella. Spring described many species and proposed the fi rst major classifi cation of this ancient lycophyte genus. His contribution to our knowledge of Selaginella was signifi cant. Th erefore, it is fi tting that this species collected at high elevations bears his name.
Conservation status. As mentioned, Selaginella neospringiana is known only from the type collection made 135 years ago. It has apparently not been collected since, even though the area where it was gathered is visited by trekkers and adventurers. Taking this into account, this species is considered Endangered (En).

Selaginella pellucidopunctata
Habitat and distribution. Selaginella pellucidopunctata grows along stream banks or near bushes in fl agstones of inselbergs in the Atlantic semi-deciduous forest vegetation at 300-650 m. It is known only from the states of Alagoas and Pernambuco in Brazil.
Etymology. Th e specifi c epithet is derived from the Latin pellucidus, meaning translucent, and punctatus, dotted; this alludes to many, conspicuous stomata on the greenish upper surfaces of dorsal sporophylls that resemble translucent dots.
Conservation status. Given that few collections are available, I cannot provide a defi nitive conservation status assessment of Selaginella pellucidopunctata. Nevertheless, this species occurs in one of the most critically endangered ecoregions of Brazil, the Atlantic Pernambuco interior forest of Northeaster, which is highly deforested with only fi ve percent of the original vegetation present (WWF 2015). Th erefore, S. pellucidopunctata is preliminarily considered Endangered (En).
Additional specimens examined ( is a species characterized by its lateral leaves with the upper surfaces hispidulous with prickle-or tooth-like projections usually found submarginally, marginally, and apically along the basiscopic halves of the laminae, and with conspicuous, straw-colored midribs. Another specimen, Lopes 593 at RB ([RB 375877]-image!) is identifi ed as S. tenuissima Fée, which is a creeping to prostrate species with usually cordate median leaves.
Habitat and distribution. Selaginella stomatoloma is an epipetric species known only from the state of Pará in Brazil. It grows in dense lowland to premontane wet forests, probably at 200-800 m.
Etymology. Th e specifi c epithet is derived from the Greek stoma, meaning mouth, and loma, fringe or border; together these refer to the many stomata found on leaf margins.
Conservation status. Selaginella stomatoloma is known only from three collections made in de Carajás National Forest, Brazil. Th is area is threatened by deforestation due to cattle ranching and large-scale mining (Pinheiro et al. 2012). Th erefore, S. stomatoloma is considered Vulnerable (VU).
Th e presence of stomata along leaf margins seems to be a more common feature in Selaginella than previously realized. Th is distribution was shown to occur in several species by, for example, Harvey-Gibson (1897), Schulz et al. (2010), Youguang and Tan (2013), and Valdespino et al. (2015), and are described here in S. nanuzae (Fig. 1, 2), S. neospringiana (Fig. 4), S. pellucidopunctata (Fig. 7, 8), S. stomatoloma (Fig. 10), and S. trygonoides (Fig. 12), as well as being present on the outer margin of median leaves of S. roraimensis Baker (see Fig. 11C in Alston et al. 1981: 284, shown as S. scintillata Alston). Youguang and Tan (2013) hypothesized that leaf marginal stomata were non-functional; however, the widespread occurrence of this feature in morphologically distinct species from diverse regions of the world indicate the contrary, particularly when one considers their fundamental role in plant physiology. It seems evolutionarily ineffi cient for Selaginella to develop leaf marginal stomata (as well as on other parts of the lamina), besides those along the midribs, if they were not active in playing key roles in plant photosynthesis. In the absence of experimental evidence to the contrary, they are here considered functional. Nevertheless, these competing explanations for the distribution and physiological importance of stomata on Selaginella highlight the need for detailed experimental studies, to address functional issues. Description. Plants terrestrial or epipetric. Stems ascending to erect, stramineous, 3-5 cm long, 0.2-0.5 mm diam., non-articulate, not fl agelliform or stoloniferous, 1-or 2-branched. Rhizophores axillary, borne on proximal ¼-½ of stems, fi liform, 0.1 or 0.2 mm diam. Leaves heteromorphic throughout, chartaceous, both surfaces glabrous, upper surfaces green, lower surfaces silvery green. Lateral leaves spreading or ascending, ovate-deltate or ovate-elliptic, 1.5-2.2 × 0.8-1.1 mm; bases rounded, acroscopic bases strongly overlapping stems, basiscopic bases free from stems; acroscopic margins broadly hyaline in a band 2-6 cells wide with the cells elongate, straight-walled, and papillate parallel to margins, papillae in 1 row over each cell lumen, short-ciliate along proximal ½, otherwise dentate distally; basiscopic margins on upper surfaces greenish comprising quadrangular, sinuate-walled, glabrous and papillate cells, on lower surfaces broadly hyaline in a band 2-6 cells wide with the cells as along acroscopic margins, dentate to denticulate throughout; apices acuminate, each acumen 0.1 or 0.2 mm, variously tipped by 1-3 teeth; upper surfaces comprising rounded or quadrangular, sinuate-walled cells, some of these covered by 3-11 papillae, without idioblasts or stomata, lower surfaces comprising elongate, sinuate-walled cells, with few of these papillate and idioblast-like on both sides of the midribs, papillae in 1 row over each cell lumen, with stomata in 2 or 3 rows along midribs and throughout acroscopic half of the lamina. Median leaves imbricate or distant, ascending, broadly ovate-elliptic, 0.8-1.2 × 0.5-0.9 mm; bases rounded to slightly oblique; margins broadly hyaline in a band 3-7 cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in 1 row over each cell lumen, short-ciliate throughout or along proximal ⅔ and dentate distally; apices long-aristate, each arista 0.4-0.6 mm, denticulate on upper surfaces, tipped by 1-3 teeth; both surfaces with- out idioblasts, upper surfaces comprising rounded or quadrangular, sinuate-walled cells, many of these covered by 4-14 papillae, with stomata in 4 rows along midribs, few scattered throughout inner halves and on margins of outer halves of the laminae, lower surfaces comprising elongate, sinuate-walled cells, without stomata. Axillary leaves similar to lateral leaves, except for both margins hyaline and short-ciliate along proximal ½ and distally dentate. Strobili terminal on branch tips, loosely quadrangular, 0.5-1.0 cm. Sporophylls monomorphic to subdimorphic, without a laminar fl ap, each with a strongly developed and dentate keel along midribs, ovate to ovatelanceolate, 0.9-1.2 × 0.4-0.6 mm; bases rounded; margins broadly hyaline (this more obviously so on dorsal sporophylls), short-ciliate or dentate on ventral sporophylls; apices acuminate to short-aristate, each acumen (arista) 0.2-0.4 mm with margins dentate and tipped by 1 or 2 teeth; dorsal sporophylls with upper surfaces green and cells as in median leaves, including stomata, lower surfaces silvery green and comprising elongate, sinuate-walled cells; ventral sporophylls with both surfaces hyaline, comprising elongate, sinuate-walled cells. Megasporangia in 2 ventral rows; megaspores yellow, mostly immature, rugulate-reticulate on proximal faces with a prominent equatorial fl ange, reticulate on distal faces, microstructure not determined, ca. 200 μm. Microsporangia in 2 dorsal rows; microspores light orange, ornamentation and microstructure not determined.

Selaginella trygonoides
Habitat and distribution. Selaginella trygonoides is known only from the state of Minas Gerais, Brazil, where it may be endemic. It grows on creek banks in Gallery forests or Atlantic semi-deciduous forests vegetation at 185-300 m.
Etymology. Th e specifi c epithet is derived from the Latin "trigon/trygonus", meaning stingray; it alludes to the shape of the median leaf, which resembles these marine fi sh.
Conservation status. Selaginella trygonoides is known only from two collections made within or nearby populated areas; most likely it is subjected to anthropomorphic pressures. Th us, I tentatively consider it Vulnerable (VU).
Discussion. Selaginella trygonoides is morphologically close to S. glazioviana, but it is distinguished from the latter by the characters of leaf surfaces and apex type, as well as median leaf marginal projections, as discussed in the diagnosis. In addition, S. trygonoides grows in lowland vegetation at 185-300 m, whereas S. glazioviana is found in montane vegetation at 900-1600 m. Selaginella glazioviana was thought to be conspecifi c with S. erectifolia Spring by Alston (1936), Reed (1965Reed ( -1966, and Alston et al. (1981), but I consider these taxa to be distinct species (see discussion under S. glazioviana). Selaginella trygonoides diff ers from S. erectifolia by its lateral leaves ovate-deltate (vs. ovate) with the acroscopic margins short-ciliate along proximal ½ (vs. dentate) and apices acuminate (vs. acute), the median leaves with short-ciliate (vs. dentate) margins, apices long-aristate (vs. short-aristate) with each arista ½ (vs. ¼) the length of the lamina, the upper surface with (vs. lacking) stomata on the inner half of the leaf lamina and some cells with the lumen covered by 4-8 (vs. 14-25) papillae. Another collection, Almeida & Souza 336 (PMA!), gathered in the same general locality of Selaginella trygonoides, is provisionally referred to S. decomposita Spring. Th is collection is similar to S. trygonoides in having lateral leaves acuminate and median leaves aristate; however it diff ers by its prostrate to ascending habit, stems to 3-branched, dorsal and ventro-axillary rhizophores, shiny leaves, median leaves dentate throughout with prominent outer bases, lateral leaves ovate-oblong to oblong, and axillary leaves ovate-lanceolate to ovate-elliptic.  (Smith 1990). It is now known from the Brazilian side of this mountain. It is terrestrial or epiphytic and characterized by having axillary rhizophores, median leaves broadly ovate to semicordate with the outer base prominently lobed and the inner base oblique, the margins narrowly hyaline (more so on inner ones) and denticulate, and the lamina abruptly tapering towards the apex, the lateral leaves broadly ovate to semicordate with the acroscopic half almost twice as wide as the basiscopic half, the acroscopic margin narrowly hyaline to greenish, the basiscopic margin greenish, and both margins denticulate to entire.  Alston et al. (1981) considered Selaginella cabrerensis endemic to Colombia and , Cremers et al. (2007), and  recorded it in Venezuela. However, as already pointed out in , I consider specimens determined as such from Venezuela as a diff erent taxon (i.e., S. boomii). Kessler et al. (2006) considered Selaginella cabrerensis as a synonym of S. xiphophylla Baker and then described S. arroyoana M. Kessler &A.R. Sm. andS. chiquitana M. Kessler, A.R. Sm. &M. Lehnert from Bolivia. Later, Huaylla et al. (2010) synonymized S. chiquitana under S. arroyoana. Valdespino (2015c) suggested that S. arroyoana and S. chiquitana might be the same taxon as S. cabrerensis, and not conspecifi c with S. xiphophylla. After examining type material of all these taxa and SEM studies, I conclude that: a) S. arroyoana and S. chiquitana are conspecifi c with S. cabrerensis, which has nomenclatural priority; b) S. cabrerensis and S. xiphophylla are related but distinct taxa as advanced by Valdespino (1993Valdespino ( , 2015c; and c) S. cabrerensis and S. xiphophylla and, at least, S. densifolia Spruce, S. falcata, and S. kochii Hieron., form a morphologically similar alliance (Valdespino 1993) here termed the "Selaginella falcata group". Th is group is currently under revision (Valdespino in prep.), and a preliminary key to distinguish them is provided below.

Selaginella cabrerensis
I conclude that S. cabrerensis is more widely distributed in South America than previously thought, occurring in French Guiana and of more widespread occurrence in Brazil (states of Goiás and Mato Grosso); it was previously known in Brazil only from Mato Grosso do Sul, where it was identifi ed as S. chiquitana by Assis and Labiak (2009).
Preliminary key to species of the Selaginella falcata group 1 Median leaf apices acute to short-acuminate, if the latter each acumen less than ¼ the length of the lamina. 2 Lateral leaves strongly imbricate along main stem, the apices obtuse to truncate or broadly acute; median leaves margins hyaline, in a band 4-6 cells wide, the outer bases prominent with 1 or 2 cilia .  Alston (1936), Reed (1965Reed ( -1966, Alston et al. (1981), and Hirai and Prado (2000). As currently circumscribed, however, S. marginata is morphologically variable and ill-defi ned. My preliminary revisionary work on S. marginata, including SEM studies of leaves and spores, indicates it is a species complex (here termed the "Selaginella marginata complex") that could include, at least, fi ve taxa (Valdespino in prep.). Among these, S. chromatophylla and S. parviarticulata Buck are very similar because of their small leaf size. Selaginella chromatophylla diff ers from the latter by its lateral and axillary leaves with peltate (vs. basally attached) bases, lateral leaves with acroscopic margins short-ciliate along proximal ½ (vs. entire), median leaves with the peltate auricles ciliate (vs. entire or almost so), and microspores gemmate or globular (vs. corrugate). It diff ers from typical S. marginata by its lateral leaves broadly ovate-elliptic (vs. ovate-deltate) with the peltate auricles ⅙ (vs. ⅓-½) the length of the laminae, both halves of the laminae of equal width (vs. acroscopic halves wider than the basiscopic ones) with obtuse to broadly acute (vs. acuminate) apices, axillary leaves obovate-oblong (vs. ovate-deltate) with obtuse to broadly acute (vs. acuminate) apices, median leaves with acute (vs. long-acuminate) apices, and gemmate or globular (vs. echinulate) microspores. Selaginella chromatophylla diff ers further from the previously discussed S. marginata and S. parviarticulata by its stems usually branching in a zig-zag pattern.
Th e name Selaginella chromatophylla is provisionally used here for the taxon documented with specimens cited pending a full nomenclatural and taxonomic revision of the rest of the species in the "Selaginella marginata complex". Other names that could potentially apply to that taxon are Selaginella excurrens Spring and S. distorta (Spring) Spring, which if proven to be conspecifi c would both have priority over S. chromatophylla.  Reed (1965Reed ( -1966 treated S. deltoides as a valid species and, apparently, subsumed S. trifurcata under it. Later, Alston et al. (1981) synonymized S. deltoides and S. trifurcata under S. muscosa. Valdespino (1995) considered S. deltoides and S. trifurcata as conspecifi c but not the same species as, or closely related to, S. muscosa. In Alston et al. (1981: 298) a possible inadvertent lectotypifi cation for S. deltoides and S. trifurcata, in the sense outlined by Prado et al. (2015), could be inferred. Furthermore, specimens of Spruce 2535 at BR! and RB! [RB 168977] are mixed collections which I have determined as: a = S. dendricola and b = S. calceolata Jermy & Rankin, while the same collection at G! and P! [P04026284] is S. dendricola.

Selaginella deltoides
Another duplicate of Spruce 2535 at P ([P01244267]-image!) was also determined by Cremers as S. dendricola. Th ese nomenclatural and taxonomic matters will be further discussed in a separate paper (see comment about this under S. glazioviana).
Selaginella deltoides is characterized by its ovate-deltate lateral leaves, with midribs conspicuously hyaline and upper surfaces hispidulous with prickle-or tooth-like projections usually found submarginally, marginally, and apically along the basiscopic halves of the laminae, and median leaves orbiculate or broadly ovate-elliptic. Selaginella deltoides, along with a species currently being described with the epithet of "aculeatifolia" (Venezuela), S. brevifolia (Colombia, Venezuela, and Brazil), and S. sandwithii Alston (Guyana and French Guiana) form a closely related group of taxa referred as the "Selaginella deltoides group" (Valdespino in press).

Selaginella falcata (P. Beauv.) Spring
Selaginella falcata (P. Beauv.) Spring (1981), Selaginella falcata was documented only in French Guiana; here its range is extended to include Brazil. Th is is a very distinct species because of its creeping to prostrate habit, ovate-deltate or deltate median leaves, large oblong, lateral leaves each 4-7.5 mm long, and main stem width (including lateral leaves) 8.0-15 mm. In Brazil, S. falcata may be confused with S. mendocae Hieron., because of their similar habit and stem width (including lateral leaves). However, the former diff ers from the latter by ovate-deltate or deltate (vs. orbiculate) median leaves, with both halves equal in width (vs. outer halves wider than inner ones), and leaf bases cordate (vs. bases oblique or inner ones truncate and outer bases lobed). Another species with similar median leaves as those of S. falcata is S. kochii. Th ese two taxa are part of the S. falcata group and can be separated by the characters provided in the key under S. cabrerensis.  Cremers et al. (2007) and  also cited it in Venezuela, and Tropicos (2015a) registered it from Ecuador. I believe that specimens from Costa Rica and Panama are most likely S. anceps (C. Presl) C. Presl, while those from Venezuela are best referred to another species. Selaginella lechleri is documented here to occur in the states of Acre and Amazonas, Brazil. It is characterized by its erect habit, lateral leaves with the basiscopic bases geniculate and usually glabrous, with the acroscopic margins short-ciliate along proximal ⅓ or dentate, otherwise sparsely denticulate to entire or serrate distally, and acuminate median leaves.  ); its range is now extended to include Brazil. Th is species is characterized by being a minute, creeping plant with coriaceous leaves, the median leaves ovate, ovate-deltate with oblique to rounded bases with the outer ones prominent. Furthermore, these leaves have prominent, often arcuate midribs (making the halves of the laminae unequal), serrate to serrulate margins, and acute apices; the lateral leaves are broadly ovate-elliptic with thickened margins, these denticulate to entire, and acute apices tipped by 1-3 teeth. In Brazil, Selaginella microdonta may be confused with S. wurdackii, from which it diff ers by its creeping habit and smaller median leaves with acute apices. According to Valdespino (1992), S. microdonta is morphologically related to S. cardiophylla Valdespino and S. hemicardia Valdespino. Th e possible interrelationships and distinguishing characters are further discussed in Valdespino (1992).  , but Cremers et al. (2007) reported it recently from Guyana, a report that needs to be confi rmed. Its range is also here documented in Brazil.

Selaginella potaroensis Jenman
Selaginella vernicosa is most distinct by its ascending to erect habit, coriaceous, strongly imbricate and shiny leaves due to waxy deposits, the median leaves ovate to ovate-deltate with the midribs raised or prominent, with short-ciliate margins at least along proximal ⅔, otherwise dentate on distal ⅓, carinate, acute apices, lateral leaves ovate-deltate with acroscopic margins short-ciliate along proximal ½, otherwise dentate distally, and basiscopic margins ciliate along proximal ¼-½, otherwise entire distally with the apices entire or tipped by a tooth.   and is reported here for the fi rst time from Brazil. It is characterized by its ascending to erect habit with axillary rhizophores, median leaves ovate, narrowly ovate-deltate to ovatelanceolate with prominent or keeled midribs that may be displaced (i.e., curved) to one side making the halves of the laminae unequal, leaf margins greenish to faintly hyaline, seemingly entire or denticulate along distal ½ and with long-acuminate to short-aristate apices, and lateral leaves ovate-elliptic with margins thickened and apices acute to short-acuminate.