From the Guiana Highlands to the Brazilian Atlantic Rain Forest: four new species of Selaginella (Selaginellaceae – Lycopodiophyta: S. agioneuma, S. magnafornensis, S. ventricosa, and S. zartmanii)

We describe four new species in the genus Selaginella (i.e., S. agioneuma, S. magnafornensis, S. ventricosa, and S. zartmanii) from Brazil, all presently classified in subg. Stachygynandrum. For each of the new taxa we discuss taxonomic affinities and provide information on habitat, distribution, and conservation status. In addition, line drawings and scanning electron microscope (SEM) images of stems sections, leaves, and spores (when present) are included. Selaginella agioneuma and S. magnafornensis are from the State of Espíritu Santo where they inhabit premontane to montane Atlantic rain forests in the Reserva Biológica Augusto Ruschi and Parque Estadual Forno Grande, respectively. Selaginella ventricosa was collected in upper montane forests at Parque Nacional Serra da Mocidade, State of Roraima and S. zartmanii in premontane Amazon rain forests on upper Rio Negro at Mpio. São Gabriel da Cachoeira, Amazonas State in both Serra Curicuriari and the Morro dos Seis Lagos Biological Reserve.


MATERIALS & METHODS
This study is based on examination of herbarium specimens from INPA, NY, P, and PMA, and digitized images from P (herbarium acronyms follow Thiers, 2018). Additional virtual herbaria consulted included RB (JBRJ, 2018), Reflora (2018), andSpecies Link (2018). Scanning electron microscopy (SEM) micrographs from selected specimens to document leaf surfaces and sculpturing patterns of mega-and microspores (when available), from designated holotypes were prepared, viewed, digitized and post-processed according to standard techniques using an image-handling software as referenced in Valdespino (2017a) and Valdespino (2017b). Terminology, measurements, and conservation status provided for each taxon follow relevant glossaries (Punt et al., 2007;Hesse et al., 2009;Beentje, 2016), andValdespino (2016), Valdespino (2017b), and references therein. Nonetheless, we believe it appropriate to further explain some terms such as ''idioblasts,'' which refer to those cells that differ from surrounding ones in shape (i.e., in this case they are elongate), size or function (see Beentje, 2016), regardless of the chemical composition of their intercellular or cell wall projections, which look like a continuous stripe or line. Equally, we use the term ''papilla (pl. papillae)'' to refer to single, discrete, round and small, nipple-like, cell surface projections. On the other hand, ''idioblast-like'' denote cells with independent papillae closely arranged in one or more rows, which may appear line-like or cells with interconnected papillae resembling a continuous stripe or line. Furthermore, we termed ''papillate cells'' those leaf cells that do not significantly differ from surrounding cells, which may have a single or many papillae and tend to be roundish to quadrangular with sinuate walls. Additionally, we define ''prickles'' or ''tooth-like'' projections as few, scabridulous, leaf surface hairs (similar to those often found in denticulate margins), which are only visible with high magnification. We abstain from referring to any of these cells or projections as being made of silica bodies because determining their chemical composition (see Prychid, Rudall & Gregory, 2004, for review) was not part of the scope of the present study. Furthermore, Valdespino (1995) discussed the term ''laminar flap'' and defined it as a laminar projection formed by a partial or continuous, incomplete fusion of the lower (adaxial) epidermis of the lower half of the dorsal sporophyll, which has the rest of that surface free and usually standing at an angle of ca. 90 • . It was depicted in Valdespino (2015a, Fig. 8F) for S. pellucidopuctata Valdespino and Valdespino (2017a, Fig. 2D) for S. hyalogramma Valdespino.
The electronic version of this article in Portable Document Format (PDF) will represent a published work according to the International Code of Nomenclature for algae, fungi, and plants (ICN), and hence the new names contained in the electronic version are effectively published under that code from the electronic edition alone. In addition, new names contained in this work which have been issued with identifiers by IPNI will eventually be made available to the Global Names Index. The IPNI LSIDs can be resolved and the associated information viewed through any standard web browser by appending the LSID contained in this publication to the prefix ''http://ipni.org/''. The online version of this work is archived and available from the following digital repositories: PeerJ, PubMed Central, and CLOCKSS. Diagnosis:-Selaginella agioneuma differs from S. contigua Baker by its dentate (vs. ciliate) median leaves with entire outer bases (vs. tufted with two to five cilia) and aristate apices with each arista 0.5-1.5 mm (vs. apices acuminate to aristate with each acumen or arista 0.05-0.7 mm) long, oblong or broadly ovate-oblong (vs. narrowly oblong) lateral leaves, each 4.0-7.5 × 1.5-3.5 mm (vs. 7.0-10 × 2.0-2.7 mm) with dentate (vs. ciliate at least along proximal 1/2) acroscopic bases, broad and abruptly tapering (vs. narrow and gradually tapering) apices ending in an acute tip, and axillary leaf margins denticulate or the inner margins denticulate along proximal 1/2 and entire distally and the outer margins denticulate throughout (vs. both margins ciliate at least along proximal 1/3-1/2, otherwise denticulate to entire). Description:-Plants terrestrial. Stems decumbent to ascending, stramineous, 15-30 cm long, 1.0-1.5 mm diam., non-articulate, not flagelliform or stoloniferous, 2-to 3-branched. Rhizophores ventral and dorsal, borne on proximal 1/3-1/2 of stems, stout, 0.4-0.8 mm diam. Leaves heteromorphic throughout, chartaceous to coriaceous, strongly imbricate, upper surfaces smooth and green, lower surfaces smooth and green and yellowish green. Lateral leaves perpendicular to the stems or slightly ascending, oblong or broadly ovateoblong, 4.0-7.5 × 1.5-3.5 mm; bases rounded to semicordate, glabrous, acroscopic bases strongly overlapping stems, basiscopic bases free from stems; acroscopic margins hyaline in a band two to four cells wide with the cells elongate, straight-walled and papillate parallel to margins, papillae in one row over each cell lumen, denticulate along proximal 1/2, then becoming entire and again denticulate along distal 1/4 or denticulate throughout, basiscopic margins narrowly hyaline, comprised of quadrangular, sinuate-walled, glabrous cells, entire along proximal 3/4, otherwise denticulate on distal 1/4; apices acute to apiculate, variously tipped by three to five teeth; upper surfaces comprised of quadrangular or rounded, sinuate-walled cells, with many idioblasts on both sides of the midribs and without stomata or sometimes with submarginal to marginal stomata along basiscopic margins, lower surfaces comprised of elongate, sinuate-walled cells, papillate idioblast on both side of the midribs, papillae in one row over each cell lumen, with stomata in six to nine irregular rows along midribs and sparsely distributed on submarginal to marginal portion of the acroscopic half of the leaf. Median leaves ascending, ovate to broadly ovate, 2.3-3.2 × 1.5-2.2 mm; bases subcordate, glabrous; margins hyaline in a band two to four cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in 1 row over each cell lumen, inner margins dentate to short-ciliate throughout, the outer margins entire along proximal 1/2, dentate to short-ciliate along distal 1/2; apices long-aristate, each arista 1/4-1/2 the length of the laminae (0.5-1.5 mm long), dentate and variously tipped by one to three teeth and with one to four short tooth-like projections on its upper surfaces; upper surfaces with conspicuous idioblasts, comprised of quadrangular, rectangular or rounded, sinuate-walled cells, with stomata in two to four rows along the midribs and sparsely present on submarginal portion along outer and inner halves of the laminae, lower surfaces comprised of elongate, sinuate-walled cells, without stomata. Axillary leaves similar to lateral leaves or more ovate or narrowly ovate, 4.0-5.0 × 1.5-3.0 mm; bases subcordate, glabrous; margins hyaline, denticulate or the inner margins denticulate along proximal 1/2 and entire distally and the outer margins denticulate throughout; apices acute to apiculate, variously tipped by one to three teeth; both surfaces as in lateral leaves.

Discussion
S. agioneuma is a very distinct species characterized by its decumbent to ascending habit, ventral and dorsal, stout rhizophores, upper surfaces of leaves usually with idioblasts, median leaf apices long-aristate with each arista denticulate and tipped by one to three teeth, and lemon yellow megaspores. In addition, the acroscopic halves of the lateral leaves are twice as wide as the basiscopic halves (i.e., 2.0 × 1.0 mm wide), while the inner halves of the median and axillary leaves are 1/2 wider than the outer halves (i.e., 1.5 × 1.0 mm wide) and the halves of the dorsal and ventral sporophylls that overlap with each other are 1/2 smaller than the halves that do not overlap. Selaginella agioneuma is morphologically similar to S. contigua by having a decumbent to ascending habit, idioblasts on the upper leaf surfaces, median leaf apices which taper into a long arista (which are long-acuminate to short-or long-aristate in S. contigua), and yellow megaspores. In addition, it somewhat resembles S. nanuzae Valdespino, and S. mendocae Hieron., because of its habit, stem width (including lateral leaves), and overall leaf shape. Nevertheless, S. agioneuma differs from S. contigua by the characters listed under the diagnosis, while from S. nanuzae it is easily distinguished by its smooth, green upper and lower leaf surfaces (vs. upper surfaces bumpy and green, and lower surfaces corrugate to striate and silvery green), median leaf inner margins dentate to short-ciliate throughout and the outer margins entire along proximal 1/2, otherwise dentate to short-ciliate along distal 1/2 (vs. margins long-ciliate throughout and more obviously so on outer margins, where the cilia are half to one time longer than the inner cilia), the bases subcordate and glabrous (vs. truncate or oblique with outer bases auriculate, the auriculae tufted with 10-18 cilia), the axillary leaves 4.0-5.0 × 1.5-3.0 mm (vs. 1.5-2.6 × 0.8-1.1 mm); the lateral leaf bases denticulate along proximal 1/2, then becoming entire and again denticulate along distal 1/4 or denticulate throughout (vs. long-ciliate along proximal 3/4, otherwise denticulate distally), basiscopic margins entire along proximal 3/4, otherwise denticulate on distal 1/4 (vs. long-ciliate along proximal 1/8, otherwise entire distally or denticulate on distal 1/8); apices acute to apiculate (vs. falcate and acute or gradually tapering and acute). Selaginella agioneuma differs from S. mendocae (which has obscure idioblasts on the upper and lower surfaces of the leaves and sporophylls, and yellow megaspores) by the upper surfaces of the leaf smooth (vs. strongly corrugate), median leaf outer margins entire along proximal 1/2, otherwise dentate to short-ciliate along distal 1/2 (vs. long-ciliate throughout), long-aristate (vs. cuspidate to shortly acuminate) apices, each arista 1/4-1/2 the length of the laminae (vs. 1/20-1/10), 0.5-1.5 (vs. 0.1 or 0.2) mm long, and oblong or broadly ovate-oblong (vs. oblong) lateral leaves with the basiscopic bases entire (vs. long-ciliate along ca. 1/10 of the proximal base), and with broad and abruptly tapering apices ending in an acute tip (vs. truncate).
Additionally, similarities in habit and stem width (including lateral leaves) might cause S. agioneuma to be confused with other Brazilian species of the genus such as S. breynii Spring, S. falcata (P. Beauv.) Spring, and S. flexuosa Spring. Nevertheless, S. falcata has ovate-deltate median leaf with bases cordate, each lobe ciliate, margins ciliate, and acuminate toothed apices that tend to lift up, the acroscopic 1/4 of the lateral leaf ciliate, and axillary leaves narrowly lanceolate to lanceolate. On the other hand, S. breynii has median leaf outer margins distinctly ciliate throughout, incurved midribs with the longaristate apices interlocking with the distal portion of the leaf apices above, the outer bases ciliate, the lateral leaf proximal 1/4 long-ciliate, otherwise distally dentate with the midribs on lower surfaces distinctly marked, the basiscopic margins long-ciliate along proximal 1/8, the apices mostly gradually tapering into a broad acute tip, and the axillary leaf narrowly lanceolate to lanceolate. Finally, S. flexuosa has leaves upper surfaces distinctly corrugate, median leaf margins denticulate with long toothed aristae abruptly born at the apices, which frequently interlock with the laminae of the leaves above them, the lateral and axillary leaves margins entire to minutely denticulate, and the lower surfaces of the leaves with many, elongate, idioblasts. corrugate) upper leaf surface, ovate-oblong (vs. oblong) lateral leaves with acroscopic margins shortly ciliate to dentate along proximal 1/3-1/2 of each lamina (vs. denticulate along proximal 1/3, otherwise entire), and ovate, ovate-oblong, ovate-cordate or narrowly ovate (vs. elliptic to oblong-elliptic) axillary leaves, and yellow (vs. white) megaspores. Description:-Plants terrestrial. Stems ascending, stramineous, 15-25 cm long, 0.4-0.8 mm diam., non-articulate, not flagelliform or stoloniferous, 2-or 3-branched. Rhizophores ventral, axillar, and dorsal, borne on proximal 1/8-1/3 of stems, stout, 0.1-0.5 mm diam. Leaves heteromorphic throughout, chartaceous to slightly coriaceous, strongly distant, upper surfaces smooth and green, lower surfaces smooth and silvery green. Lateral leaves perpendicular to the stems or slightly ascending, ovate to ovate-oblong, 1.7-2.5 × 0.8-1.5 mm; bases rounded to semicordate, glabrous, acroscopic bases strongly overlapping stems, basiscopic bases free from stems; acroscopic margins hyaline in a band one to six cells wide (usually one to three cells wide on basiscopic margins) with the cells elongate, straight-walled and papillate parallel to margins, papillae in one row over each cell lumen, shortly ciliate to dentate along proximal 1/3-1/2, otherwise denticulate apically, basiscopic margins narrowly hyaline to greenish hyaline in a band one to three cells wide, the cells as in acroscopic margins, denticulate; apices acute, variously tipped by two to four teeth; upper surfaces comprised of quadrangular or rounded, sinuate-walled cells, many of these along submarginal portion of basiscopic halves and apical 1/4 of the laminae covered by 2-12 papillae, without idioblasts or stomata, lower surfaces comprised of elongate, sinuate-walled cells and many papillate idioblast on both sides of the midribs, the idioblasts three to six longer than surrounding cells and somewhat interconnecting as to appear veins (i.e., false veins), papillae in one row over each cell lumen, with stomata in one or two rows along proximal 3/4 of the midribs and at least one or few scattered on proximal, submarginal 1/2 of acroscopic margins and on distal 1/3 of the margins. Median leaves ascending, ovate-elliptic, 1.0-1.8(2.0) × 0.8-1.4 mm; bases oblique, glabrous; margins hyaline in a band two to four cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in one row over each cell lumen, margins dentate; apices long-aristate, each arista 1/3-1/2 the length of the laminae (0.4-0.7 mm long), dentate and variously tipped by one to four teeth; both surfaces without conspicuous idioblasts, upper surfaces comprised of quadrangular, rectangular or rounded, sinuate-walled cells, many of these covered by 6-14 papillae, with stomata in one row along distal 1/2 of the midribs, sparsely present on submarginal portion along proximal 1/4 of outer halves of the laminae, lower surfaces comprised of elongate, sinuate-walled cells, without stomata. Axillary leaves similar to lateral leaves or broadly ovate, 1.8-2.4 × 1.0-1.5 mm; bases rounded, glabrous; margins narrowly hyaline, margins dentate to denticulate; apices acute, variously tipped by one to three teeth; both surfaces as in lateral leaves, except for stomata along distal 1/2 of the laminae and margins. Strobili terminal on main stem and branch tips, quadrangular, 3.0-8.0 cm. Sporophylls monomorphic, without a laminar flap, each with a well developed and seemingly glabrous keel (as observed with SM) along midribs, ovate-lanceolate, 0.9-1.2 × 0.5-0.7 mm; bases rounded; margins slightly hyaline, dentate; apices acuminate to aristate, each acumen or aristae 0.  Discussion S. magnafornensis is a very distinct species with slender stems with well-spaced branches (1.0-1.5 cm apart) that bear strobili at their tips. It does not seem to have close morphological affinities with other Brazilian Selaginella species but its creeping stems, somewhat stiff and long-aristate median leaves are reminiscent of slender forms of S. flexuosa, however, the characters listed in the diagnosis set them apart.  apices tipped by four to six teeth (vs. by three to five long cilia), with (vs. without) stomata on the upper surfaces, and stomata lacking (vs. present) on the lower surfaces. It also differs from S. microphylla by the median leaf inner hyaline margins along distal 1/2 and the outer hyaline margins along distal 2/3 with the papillae of the cells interconnected (vs. papillae distinct) and appearing (vs. not) idioblast-like, and lower surfaces of lateral leaves with many (vs. some) papillate idioblasts, the idioblasts long (vs. short) with papillae mostly in 2 (vs. two to four) rows or in a single interconnected row (vs. always in two or more distinct rows) of papillae. Description:-Plants epiphytic. Stems creeping, stramineous, 7.0-14.5 cm long, 0.4-0.6 mm diam., non-articulate, not flagelliform or stoloniferous, one-to two-branched. Rhizophores axillary, borne throughout the stem, filiform, 0.1-0.3 mm diam. Leaves heteromorphic throughout, membranaceous, both surfaces glabrous, upper surfaces green, lower surfaces silvery green. Lateral leaves spreading, broadly ovate or ovate-oblong, 2.0-2.7 × 1.2-2.2 mm; bases rounded, glabrous, acroscopic bases strongly overlapping the stems, basiscopic bases free from stems; acroscopic margins hyaline along proximal 1/3 in a band three to seven cells wide with the cells elongate, straight-walled and papillate parallel to margins, papillae in two rows over each cell lumen, long-ciliate along proximal 3/4, otherwise denticulate distally; basiscopic margins greenish, comprised of quadrangular, sinuate-walled, glabrous and papillate cells, short-ciliate along proximal 1/8; otherwise entire distally or denticulate on distal 1/8, apices broadly acute to obtuse, with prickles or tooth-like projections on the upper surface; upper surfaces comprised of quadrangular or rounded, sinuate-walled cells, many of these covered by 7-20 papillae, without idioblasts or stomata, lower surfaces comprised of elongate, sinuate-walled cells, with many of these papillate and with idioblasts on both side of the midribs (more so on basiscopic halves of the laminae), papillae in two to three rows over each cell lumen, with stomata in three to four rows along midribs. Median leaves distant on the main stem, ascending, broadly ovate to ovate-orbicular, 0.8-1.4 × 0.7-1.3 mm; bases truncate to oblique, glabrous, inner margins hyaline in a band two to six cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in one row over each cell lumen and often interconnected along distal 1/2 and appearing as a single line or idioblast, long-ciliate along proximal 4/5, otherwise dentate to serrate on distal 1/5, outer margins greenish along proximal 1/3 and the cells similar to those of the leaf upper surfaces, otherwise hyaline on distal 2/3 in a band one or two cells wide with the cells similar to those found on distal 1/2 of inner margins, entire along proximal 1/3, except for a single long-ciliate at proximal most portion near the base, otherwise short-ciliate on median 1/3 and dentate to serrate on distal most 1/3; apices broadly acute, 0.1-0.2 mm long, variously tipped by four to six teeth and with tooth-like or prickle projections along its length on upper surfaces; upper surfaces comprised of quadrangular, rectangular or rounded, sinuate-walled cells, many of these covered by 5-15 papillae, with stomata in one to two rows along distal 1/2-2/3 of the midribs ending before distal most apical portion of the lamina and along proximal 1/3 of outer margins, lower surfaces comprised of elongate, sinuate-walled cells, with papillate idioblasts concentrated on proximal 1/3 of the outer margins, the papillae in two rows of each cell lumen, without stomata. Axillary leaves narrowly ovate or ovate-oblong, 1.3-1.6 × 1.0-1.3 mm; bases truncate, glabrous; margins hyaline, long-ciliate along proximal 2/3, especially on inner margins, otherwise denticulate on distal 1/3; apices acute to broadly acute, variously tipped by one to three teeth; both surfaces as in lateral leaves. Strobili, sporophylls, sporangia and spores not observed because plants where unfertile. Habitat and distribution:-S. ventricosa grows as an epiphyte in upper montane Amazon forests at 1,732 m in an isolated tepui complex in the southern portion of the Guiana Plateau; it is only known from the type locality in Roraima State, Brazil, where it might be a local endemic. Recently, other plant and insect species were described from the Serra da Mocidade mountain range (see for example Bastos, Sierra & Zartman, 2016;Da Silva-Neto, Aldrete & Rafael, 2016;Dantas & Hamada, 2017) that also has an herpetofauna richness comparable to other Guiana Shield mountains (Moraes et al., 2017), thus highlighting its biodiversity importance within the region. Etymology:-The species name is derived from the Latin ''ventricosus'', meaning swollen, especially on one side, and refers to the median leaf outer halves somewhat ventricose or bulging. Conservation status:-S. ventricosa was collected in Serra da Mocidade National Park, a poorly explored and isolated tepui complex of the Brazilian Guiana Shield, that is closed to the public and thus this species is considered as Data Deficient (DD), according to IUCN categories and criteria (IUCN, 2012).

Discussion
S. ventricosa is characterized by its broadly ovate to ovate-orbicular median leaves with asymmetric halves, the outer halves 1/4 or less wider than the inner halves and somewhat appearing ventricose or bulging, truncate to oblique bases. It is further characterized by its median leaf inner margins long-ciliate along proximal 4/5, the inner margins distal 1/2 and the outer margins distal 2/3 hyaline, composed of papillate cells with the papillae interconnected appearing as a single line or idioblast, stomata along proximal 1/3 of outer margins, broadly acute apices tipped by four to six teeth, and each apex upper surface with prickles or tooth-like projections along its length and with many of the cells lumina covered by 5-15 papillae. Selaginella ventricosa is a unique species that might be confused with S. microphylla, a taxon within the species group of the same name that is also found in Brazil, by its similar creeping habit and leaves. S. ventricosa is set easily aside from the latter by the characters listed in the diagnosis and by its median leaves with truncate to oblique (vs. distinctly oblique) bases, with the inner margins long-ciliate along proximal 4/5 and outer margins short-ciliate on median 1/3 (vs. inner and outer margins usually long-ciliate throughout), and the upper surfaces with 5-15 [vs. 1-4(6)] papillae.   Lateral leaves ascending, lanceolate-oblong or ovate-oblong, 1.3-1.8 × 0.4-0.9 mm; bases rounded, glabrous, acroscopic bases overlapping stems, basiscopic bases free from stems; acroscopic margins slightly hyaline in a band two or three cells wide with the cells elongate, straight-walled and papillate parallel to margins, papillae in one row over each cell lumen, serrate throughout, basiscopic margins greenish, often revolute, comprised of quadrangular, sinuate-walled cells, serrate throughout; apices acute, variously tipped by three to five teeth; both surfaces glabrous or upper surface sometimes with marginal prickles or tooth-like projections along the distal region of basiscopic margins, upper surfaces comprised of quadrangular or rounded, sinuate-walled cells (often difficult to distinguish because of waxy deposits), many of these covered by one or two papillae, without idioblasts or stomata or sometimes with submarginal to marginal stomata along both margins, lower surfaces comprised of elongate, sinuate-walled cells, with many of these papillate and idioblast-like on both sides of the midribs, papillae in one row over each cell lumen, with stomata in four or five rows along midribs. Median leaves ascending, distant to slightly imbricate in the apical region of stems and branches, ovate-elliptic or ovate, 0.6-1.2 × 0.4-0.7 mm; bases truncate and glabrous; margins slightly hyaline in a band one to three cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in one row over each cell lumen, serrate throughout; apices aristate, arista 0.2-0.5 mm long, tipped by five or six teeth and with prickles or tooth-like projections along its length on upper surfaces; both surfaces without conspicuous idioblasts, upper surfaces comprised of quadrangular, rectangular or rounded, sinuate-walled cells (often difficult to distinguish because of waxy deposits), many of these covered by one or two papillae, with stomata in one or two rows along distal 1/2 of the midribs, sparsely present on submarginal portion along proximal 1/3 of outer halves of the laminae, lower surfaces comprised of elongate, sinuate-walled cells, without stomata. Axillary leaves lanceolate, 0.   & Forzza, 2012) and was reported in the type collection information as consisting of abundant populations there. Therefore, it presently should be classified as a least concern (LC) taxon according to IUCN criteria (IUCN, 2012).

Discussion
Selaginella zartmanii is easily confused with S. boomii because of their overall similar habit and leaves, and often having their lateral leaves basiscopic margins revolute when dry. In fact, Valdespino (2015b), included specimens here cited as paratypes of S. zartmanii under the latter. Nevertheless, a recent study conducted to identify the type collection of S. zartmanii prompted us to reassess the circumscription of S. boomii and to segregate from it those specimens from São Gabriel da Cachoeira, Amazonas State, Brazil, ascribing them to the former species. Selaginella zartmanii differs most noticeably from S. boomii by the characters listed in the diagnosis. In addition, as already advanced by Valdespino (2015b) specimens here assigned to S. zartmanii differ from typical S. boomii in having its megaspores proximal faces coarsely rugulate-reticulate (vs. slightly rugulate-reticulate to rugulate-granulate) with (vs. without) a slightly developed equatorial flange and spheroid to spheroid-perforate (vs. echinulate and perforate) microstructure and coarsely reticulate (vs. slightly rugulate-reticulate to rugulate-granulate) distal faces, the reticula with broad and coarse (vs. fainted or vestigial) muri and spheroid to spheroid-perforate (vs. echinulate and perforate) microstructure [see Figs. 16A-16D depicted here and Fig. 2A -D in Valdespino (2015b), for megaspore sculpturing pattern comparison]. This new species further differs from S. boomii by having the lower surfaces of the lateral leaves with scattered (vs. variously assembled in continuous rows of three to nine) idioblasts mostly along distal 1/2 or occasionally few proximal (vs. throughout both sides) of each leaf midrib, and glabrous leaf base cells (vs. papillate and idioblasts-like with papillae in one or two rows on each cell lumen).