Selaginella nanuzae differs from typical S. contigua Baker by its coriaceous (vs. chartaceous) leaves with the upper surfaces shiny and bumpy (vs. dull and smooth to slightly corrugate), the acroscopic margins of the lateral leaves and both margins of the median and axillary leaves broadly (vs. faintly) hyaline, median leaves with long-aristate (vs. acute to short-acuminate) apices, each arista 0.4–0.6 mm (vs. acumen 0.05–0.2 mm), midribs straight (vs. arcuate) with the outer bases auriculate (vs. lacking auricles) and bearing10–18 long-cilia (vs. outer bases ciliate with 2–5 cilia), and the lateral leaves 2.5–3.0 × 1.0–1.5 mm (vs. 7.0–10 × 2.0–2.7 mm).

BRAZIL. São Paulo: [Mpio.] Ubatuba, Parque Estadual da Serra do Mar, Núcleo Picinguaba, trail to Pico Corcovado, 23°26'56.6"S, 45°11'35.8"W, 450 m, 1 Nov 2001, A. Salino, V.A.O. Dittrich, P.O. Morais, F.A. Carvalho, L.C.R.S. Teixeira & A.M. Oliveira 7788 (holotype: PMA! [PMA103268]; isotype: BHCB [BHCB65041]-n.v.).

Plants terrestrial. Stems decumbent to ascending or suberect, stramineous, 3–5 cm long, 0.5–1.0 mm diam., non-articulate, not flagelliform or stoloniferous, 2–3-branched. Rhizophores ventral or ventro-axillary, borne on proximal ½ of stems, stout, 0.5–1.0 mm diam. Leaves heteromorphic throughout, coriaceous, strongly imbricate, upper surfaces bumpy and green, lower surfaces corrugate to striate and silvery green. Lateral leaves ascending, ovate-oblong or ovate, 1.5–3.0 × 0.9–1.5 mm; bases rounded to semicordate, acroscopic bases strongly overlapping stems, basiscopic bases free from stems; acroscopic margins broadly hyaline in a band 5–10 cells wide with the cells elongate, straight-walled and papillate parallel to margins, papillae in 1 row over each cell lumen, long-ciliate along proximal ¾, otherwise denticulate distally, basiscopic margins greenish, comprising quadrangular, sinuate-walled, glabrous and papillate cells, long-ciliate along proximal ⅛, otherwise entire distally or denticulate on distal ⅛; apices falcate and acute or gradually tapering and acute, variously tipped by 1–3 teeth; upper surfaces comprising quadrangular or rounded, sinuate-walled cells (often difficult to distinguish because of waxy deposits), many of these covered by 6–40 papillae, without idioblasts or stomata, lower surfaces comprising elongate, sinuate-walled cells, with many of these papillate and idioblast-like on both side of the midribs (more so on acroscopic halves of the laminae), papillae in 1–3 rows (or rows not clearly distinguishable) over each cell lumen, with stomata in 2–5 rows along midribs and along distal ⅙ of basiscopic margins. Median leaves ascending, ovate to ovate-elliptic or orbicular, 1.2–1.8 × 0.6–1.2 mm; bases truncate or oblique with outer bases auriculate, auriculae tufted with 10–18 cilia; margins broadly hyaline in a band 2–8 cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in 1 row over each cell lumen, long-ciliate throughout and more obviously so on outer margins (cilia on outer margins half to one time longer than the inner cilia); apices long-aristate, each arista ⅓–½ the length of the laminae (0.4–0.9 mm), variously tipped by 1–3 teeth; both surfaces without conspicuous idioblasts, upper surfaces comprising quadrangular, rectangular or rounded, sinuate-walled cells (often difficult to distinguish because of waxy deposits), many of these covered by 7–25 papillae, with stomata in 2–5 rows along distal ½ of the midribs, few on submarginal portion along proximal ⅕ of outer halves of the laminae, lower surfaces comprising elongate, sinuate-walled cells, without stomata. Axillary leaves ovate or ovate-lanceolate, 1.5–2.6 × 0.8–1.1 mm; bases rounded; margins broadly hyaline, long-ciliate along proximal ⅓, short-ciliate on central ⅓, otherwise dentate on distal ⅓; apices acute to broadly acute, variously tipped by 1–3 teeth; both surfaces as in lateral leaves. Strobili terminal on main stem and branch tips, loosely quadrangular, 0.4–1.6 cm. Sporophylls monomorphic, without a laminar flap, each with a strongly developed and seemingly glabrous keel along midribs, broadly ovate to ovate-deltate, 1.0–1.2 × 0.6–1.1 mm; bases truncate; margins broadly hyaline, dentate to short-ciliate; apices short-acuminate to cuspidate, each acumen (cusp) 0.1–0.2 mm, tipped by 1–3 teeth; dorsal sporophylls with upper surfaces green and cells as in median leaves, lower surfaces silvery green and comprising elongate, sinuate-walled cells; ventral sporophylls with both surfaces hyaline or greenish hyaline, comprising elongate, sinuate-walled cells. Megasporangia in 2 ventral rows; megaspores yellow, rugulate-reticulate on proximal faces with verrucate, perforate, and echinulate microstructure, reticulate on distal faces with verrucate and perforate microstructure (Fig. 3A–D), 260–355 µm. Microsporangia in 2 dorsal rows; microspores orange, rugulate on proximal faces with echinulate microstructure, capitate or clavate on distal faces with each caput and the rest of the surface with echinulate microstructure (Fig. 3E, F), 25–30 µm.

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.

This 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. Through 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 first exposure to, and study of, Brazilian Selaginella.

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).

(paratype). BRAZIL. São Paulo: Mpio. Ubatuba, Morro Corcovado, 8 Sep 1998, Ribas & Dittrich 2729 (NY).

Selaginella nanuzae is characterized by the upper surfaces of the leaves shiny (due to waxy deposits) and bumpy (Figs 1, 2), the median leaves long-aristate (Fig. 1A, B, E, F), the acroscopic margins of the lateral leaves (Fig. 2B–D, E, G) and both margins of the axillary and median leaves (Fig. 1B–D, F–H) broadly hyaline, as well as the apices of the lateral leaves acute (Fig. 1A, E; Fig. 2A, B, E, G).

Figure 1. 

Selaginella nanuzae Valdespino. A Section of upper surface of stem B Upper surface of median leaf C Close-up of base and proximal portion of median leaf, upper surface; note marginal (a) and submarginal (b) stoma, and outer base tufted with long cilia (c) D Close-up of distal portion and apex of median leaf, upper surface E Section of upper surface of stem F Close-up of outer half of median leaf, upper surface G Close-up-of inner half of median leaf, upper surface H Lower surface of median leaf. A–H taken from the holotype, Salino et al. 7788 (PMA).

Figure 2. 

Selaginella nanuzae Valdespino. A Section of lower surface of stem B Lower surface of lateral leaf C Close-up of base and distal portion of lateral leaf, lower surface D Close-up of acroscopic half of lateral leaf near base, lower surface E Close-up of distal portion and apex of lateral leaf, lower surface F Close-up of portion of basiscopic margin of lateral leaf near apex, lower surface; note marginal stoma (a) G Upper surface of lateral leaf H Close-up of upper surface of lateral leaf. A–H taken from the holotype, Salino et al. 7788 (PMA).

Figure 3. 

Selaginella nanuzae Valdespino. A Megaspore, proximal face B Close-up of megaspore, proximal face C Megaspore, distal face D Close-up of megaspore, distal face E Microspore, proximal face F Microspore, distal face. A–F taken from the holotype, Salino et al. 7788 (PMA).

The 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 differs from typical S. contigua, as lectotypified by Hirai and Prado (2000), by the characters given in the diagnosis. Selaginella nanuzae further differs 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.

Selaginella neoespringiana differs 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).

BRAZIL. Rio de Janeiro: Petrópolis, Morro de Cubiçado, Gularte area, [ca. 1650 m], 7 Jul 1879, A. Glaziou 11723 (holotype: C!; isotypes: BM!, P [P01282486]-image!, P [P01282487]-image!, PMA! [PMA103270], US!).

Plants terrestrial (or epipetric?). Stems ascending to erect, stramineous, 3–5 cm long, 0.05–0.1 mm diam., non-articulate, flagelliform on branches, stoloniferous, 1- or 2-branched. Rhizophores axillary, borne on proximal ¼ of stems, filiform, 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, sinuate-walled 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 flap, 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 flange and perforate microstructure, reticulate on distal faces with echinulate and perforate microstructure (Fig. 6A–D), 185–265 µm. Microsporangia in 2 dorsal rows; microspores orange, rugulate on proximal faces with echinulate microstructure, echinulate or baculate on distal faces with echinulate microstructure (Fig. 6E–I), 24–30 µm.

Figure 4. 

Selaginella neospringiana Valdespino. A Section of upper surface of stem B Upper surface of median leaf C Close-up of base and proximal portion of median leaf, upper surface D Close-up of distal portion and apex of median leaf, upper surface E Section of lower surface of stem F Lower surface of lateral leaf; note marginal stoma (a) G Close-up of proximal portion and base of lateral leaf, lower surface; note marginal stoma (a) on basiscopic margin and on outer margin of median leaf (far, lower right) H Close-up of distal portion and apex of lateral leaf, lower surface; note marginal stoma (a). A–H taken from the isotype, Glaziou 11723 (PMA).

Figure 5. 

Selaginella neospringiana Valdespino. A Lateral leaf and portions of median leaves, upper surfaces; note papillae on cells lumen and stomata (a) along midrib of median leaf B Close-up of upper surface of lateral leaf; note papillae on cells lumen. A–B taken from the isotype, Glaziou 11723 (PMA).

Figure 6. 

Selaginella neospringiana Valdespino. A Megaspore, proximal face B Close-up of megaspore, proximal face C Megaspore, distal face D Close-up of megaspore, distal face E Microspore, proximal face F Close-up of microspore, proximal face G Microspore, distal face H Close-up of microspore, distal face I Microspore, equatorial view. A–I taken from the isotype, Glaziou 11723 (PMA).

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 fields or high-altitude fields) vegetation is common. The 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.

The specific 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 first major classification of this ancient lycophyte genus. His contribution to our knowledge of Selaginella was significant. Therefore, it is fitting that this species collected at high elevations bears his name.

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).

Discussion.Alston et al. (1981) cited the type of Selaginella neospringiana under S. vestiens, but as pointed out by Valdespino et al. (2015) they are morphologically different and can be separated by the characters discussed under the diagnosis.

Selaginella pellucidopunctata differs from the similar S. muscosa Spring by its median leaves elliptic or ovate-lanceolate (vs. broadly ovate to cordate), lateral leaves with the upper surfaces with few submarginal prickle- or tooth-like projections on basiscopic halves near basiscopic margins (vs. upper surfaces glabrous), with the acroscopic margins ciliate along proximal ½ (vs. denticulate throughout), axillary leaves ovate to broadly ovate (vs. broadly ovate or cordate), and megaspores deep yellow (vs. light yellow).

BRAZIL. Alagoas: Mpio. Ibateguara, Engenho Coimbra, Grota do Vargão, [ca. 09°00'02"S, 35°51'12"W], [ca. 500 m], 12 Nov 2001, M. Oliveira 1094 (holotype: UFP! [UFP 39685]; isotype: PMA! [PMA103269]).

Plants terrestrial or epipetric. Stems ascending to erect, stramineous, 9–13 cm long, 0.4–0.7 mm diam., non-articulate, not flagelliform, shortly stoloniferous, 2–3-branched. Rhizophores axillary, borne on proximal ⅛–¼ of stems, filiform, 0.1–0.3 mm diam. Leaves heteromorphic throughout, membranaceous, both surfaces glabrous, upper surfaces green, lower surfaces silvery green. Lateral leaves spreading or slightly ascending, ovate to broadly ovate, 2.0–2.4 × 1.0–1.3 mm; bases rounded to almost semicordate, acroscopic bases strongly overlapping stems, basiscopic bases free from stems; acroscopic margins narrowly to 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, ciliate along proximal ½, otherwise dentate distally, basiscopic margins on upper surfaces greenish, comprising rounded or quadrangular, sinuate-walled cells, on lower surfaces narrowly to broadly hyaline in a band 2–4 cells wide with the cells as along acroscopic margins, denticulate throughout; apices acute to short-acuminate, each acumen 0.05–0.1 mm, variously tipped by 1–3 cilia; upper surfaces comprising rounded or quadrangular, sinuate-walled cells, some of these, particularly along submarginal and distal regions of the laminae, covered by 12–30 papillae, without idioblasts and with stomata along proximal ½ of basiscopic margins, lower surfaces comprising elongate, sinuate-walled cells, without conspicuous idioblasts (when viewed with stereomicroscope, EM) or these conspicuous (when viewed with SEM) and papillate on both sides of midribs, papillae in 1 or 2 rows over each cell lumen, with stomata in 2 or 3 rows along midribs and throughout acroscopic halves of the laminae. Median leaves distant, ascending, elliptic or ovate-lanceolate, 1.0–1.4 × 0.5–0.7 mm; bases rounded to slightly oblique; margins broadly hyaline in a band 1–7 cells wide, the cells elongate, straight-walled and papillate parallel to margins, papillae in 1 or 2 rows over each cell lumen, short-ciliate throughout or along proximal ⅔ and dentate distally or dentate throughout; apices long-aristate, each arista 0.5–0.7 mm, denticulate on upper surfaces, tipped by 1–3 cilia; both surfaces without idioblasts, upper surfaces comprising quadrangular or rounded, sinuate-walled cells, many of these covered by 7–20 papillae, with stomata in 4 rows along midribs, few stomata along proximal ¼ of outer margins, lower surfaces comprising elongate, sinuate-walled cells, without stomata. Axillary leaves similar to lateral leaves, except for both margins hyaline and long-ciliate along proximal ½, distally dentate. Strobili terminal on branch tips, dorsiventral, 0.2–1.0 cm. Sporophylls dimorphic; dorsal sporophylls spreading, with an adaxial laminar flap, each with a strongly developed and dentate keel along midribs, narrowly ovate to ovate-lanceolate, 1.5–1.8 × 0.5–0.7 mm; bases rounded; margins broadly hyaline, dentate to denticulate; apices acuminate, each acumen 0.1 or 0.2 mm with margins dentate and tipped by 2–4 teeth; upper surfaces green and cells as in median leaves, including many stomata, except for the half that overlaps the ventral sporophylls where the surfaces are hyaline with elongate, sinuate-walled cells, lower surfaces silvery green and comprising elongate, sinuate-walled cells; ventral sporophylls ascending, without a laminar flap, each with a slightly developed and dentate keel along midribs, ovate to ovate-lanceolate, 1.0–1.2 × 0.4–0.6 mm; bases rounded; margins broadly hyaline, dentate to denticulate; apices long-acuminate, each acumen 0.2 or 0.3 mm with margins dentate and tipped by 2–4 teeth; both surfaces hyaline, comprising elongate, straight-walled cells and papillate idioblasts. Megasporangia in 2 ventral rows; megaspores yellow, rugulate-reticulate on proximal faces with a prominent equatorial flange, reticulate on distal faces, with granulate-echinulate and perforate microstructure on both faces (Fig. 9A–D), 250–280 µm. Microsporangia in 2 dorsal rows; microspores orange, rugulate-echinulate on proximal faces, capitate on distal faces, with echinulate microstructure on both faces (Fig. 9E–H), 27–35 µm.

Figure 7. 

Selaginella pellucidopunctata Valdespino. A Section of upper surface of stem B Upper surface of median leaf C Close-up of base and proximal portion of median leaf, upper surface; note marginal stoma (a) on outer margin D Close-up of median leaf, distal region, upper surface E Close-up of apex of median leaf, upper and lower surfaces; note marginal stoma (a) on basiscopic margin of lateral leaf, upper surface F Upper surface of lateral leaf; note marginal stoma (a) on basiscopic margin and submarginal tooth (b) G Close-up of base and proximal portion of lateral leaf, upper surface; note marginal stoma (a) on basiscopic margin H Close-up of distal portion and apex of lateral leaf, upper surface; note submarginal tooth (b). A–H taken from the isotype, Oliveira 1094 (PMA).

Figure 8. 

Selaginella pellucidopunctata Valdespino. A Section of lower surface of stem B Lower surface of lateral leaf C Close-up of distal portion and apex of lateral leaf, lower surface; note elongate, straight-walled, and papillate cells (idioblasts) D Close-up of lateral leaf, lower surface; note elongate, straight-walled, and papillate cells (idioblasts) E Strobilus, upper surface; note dorsal (Ds) and ventral (Vs) sporophyll F Dorsal sporophylls, adaxial- (F-1) and abaxial surfaces (F-2); note acroscopic margin (Ma) and basiscopic margin (Mb), this usually referred to as laminar flap (lf), stomata (a) throughout lamina and midrib, as well as tooth-like projections (b) on midrib and lamina, abaxial (upper) surface, marginal tooth projections (c), and ligule (d) G Strobilus, lower surface; note dorsal- (Ds) and ventral (Vs) sporophyll H Ventral sporophyll, adaxial (lower) surface. A–H taken from the isotype, Oliveira 1094 (PMA).

Figure 9. 

Selaginella pellucidopunctata Valdespino. A Megaspore, proximal face B Close-up of megaspore, proximal face C Megaspore, distal face D Close-up of megaspore, distal face E Microspore, proximal face F Close-up of microspore, proximal face G Microspore, distal face H Close-up of microspore, distal face. A–H taken from the isotype, Oliveira 1094 (PMA).

Selaginella pellucidopunctata grows along stream banks or near bushes in flagstones 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.

The specific 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.

Given that few collections are available, I cannot provide a definitive 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 five percent of the original vegetation present (WWF 2015). Therefore, S. pellucidopunctata is preliminarily considered Endangered (En).

(paratypes). BRAZIL. Alagoas: Mpio. Ibateguara, Usina Serra Grande, Engenho Coimbra, [ca. 09°00'02"S, 35°51'12"S], [ca. 500 m], 15 Oct 2003, Pietrobom et al. 5637 (UFP, PMA); Mpio. São José da Lage, Usina Serra Grande, 08°59'42.4"S, 36°07'28.9"W, ca. 380–415 m, 8 Feb 2001, Pietrobom & Santiago 4807 (UFP, PMA). Pernambuco: Mpio. Jaqueira, Usina, Colônia, 08°04'15"S, 35°50'13"W, ca. 650 m, 17 Oct 2001, Lopes & Pietrobom 350 (RB-image, UFP-n.v.), 08°43'21.1"S, 35°50'22.1"W, ca. 545 m, 20 May 2002, Lopes, 593 (RB-image, UFP-n.v.); Mpio. Timbaúba, Complexo da Serra do Mascarnhas, Usina Cruangi, Engenho Água Azul, ca. 07°36'31.5"S, 35°22'42.9"W, ca. 304–394 m, 13 Nov 2000, Pietrobom et al. 4646 (UFP, PMA).

Among Brazilian Selaginella, S. pellucidopunctata most resembles S. muscosa. They differ most noticeably by the characters of the median leaf shape and the projections on the upper surfaces and margins of the lateral leaves, as discussed in the Diagnosis. In addition, the leaf surfaces of S. pellucidopunctata, when viewed with EM, seem to lack (vs. exhibit) conspicuous idioblasts. However, idioblasts are seen on SEM images of the lower surfaces of lateral leaves of S. pellucidopunctata.

One specimen, Lopes & Pietrobom 350 at RB ([RB 375875]–image!) is identified as Selaginella arenaria Baker, a synonym of S. brevifolia Baker (Valdespino 2015c), which 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 identified as S. tenuissima Fée, which is a creeping to prostrate species with usually cordate median leaves.

Selaginella stomatoloma differs from the recently described S. saltuicola Valdespino by having the upper surfaces of the leaves with glabrous (vs. papillate) cells, the lateral leaf lower surfaces without (vs. with) papillate idioblasts and with marginal cells glabrous (vs. papillate), and acute (vs. rounded to broadly acute) apices, the median leaf margins comprising slightly elongate and glabrous (vs. strongly elongate and papillate) cells, these denticulate (vs. entire), with short-acuminate (vs. acute) apices, and upper surfaces with few submedial and submarginal stomata (vs. stomata throughout laminae).

BRAZIL. Pará: Canaã dos Carajás, S11D, UTM-Zone 22M: 9293819 575625 [06°23'08"S, 50°18'58.24"W], 31 Aug 2010, T.E. Almeida et al. 2518 (holotype: PMA! [PMA103369]; isotype: BHCB [BHCB142524]-n.v.).

Plants epipetric. Stems decumbent to ascending, stramineous, 3–6 cm long, 0.2–0.5 mm diam., non-articulate, not flagelliform, stoloniferous, 1- or 2-branched. Rhizophores axillary, borne on proximal ¼–¾ of stems, filiform, 0.05 or 0.15 mm diam. Leaves heteromorphic throughout, membranaceous, both surfaces glabrous, upper surfaces green, lower surfaces silvery green. Lateral leaves spreading to ascending near branches and stem apices, ovate-elliptic to ovate-oblong, 1.5–2.0 × 0.8–0.9 mm; bases rounded, acroscopic bases slightly overlapping stems, basiscopic bases free from stems; margins greenish with the cells quadrangular, sinuate-walled, glabrous, mostly entire and denticulate near apices or denticulate throughout; apices acute and variously tipped by 1 or 2 teeth; both surfaces without idioblasts, upper surfaces comprising quadrangular to rounded, sinuate-walled, glabrous cells, with stomata submarginal, particularly on distal ½ and throughout margins, lower surfaces comprising elongate, sinuate-walled, glabrous cells, with stomata in 3–5 rows along midribs and throughout acroscopic halves of the laminae. Median leaves distant or imbricate near branches and stem apices, ascending, ovate-elliptic or elliptic, 0.7–1.1 × 0.3–0.6 mm; bases rounded to slightly oblique; margins greenish or narrowly hyaline in a band 2 or 3 cells wide, the cells slightly elongate, straight-walled and glabrous parallel to margins, denticulate throughout; apices short-acuminate, each acumen 0.05–1.05 mm, denticulate on upper surfaces, tipped by 1 or 2 teeth; both surfaces without idioblasts, upper surfaces comprising quadrangular to rounded, sinuate-walled, glabrous cells, with stomata in 1–3 rows along midribs, with a few submedial and submarginal and throughout margins, lower surfaces comprising elongate, sinuate-walled cells, without stomata. Axillary leaves similar to lateral leaves. Strobili terminal on branch tips, quadrangular, 1.5–6.0 mm. Sporophylls monomorphic, without a laminar flap, each with a strongly developed and seemingly entire or denticulate keel along midribs, ovate or the ventral ones broadly ovate, 0.9–1.2 × 0.4–0.7 mm; bases rounded; margins narrowly hyaline (less so on ventral sporophylls), denticulate; apices acute to short-acuminate, each acumen 0.05–0.1 mm with margins dentate and tipped by 1–2 teeth; dorsal sporophylls with upper surfaces green and cells as in median leaves, including stomata, lower surfaces greenish and comprising elongate, sinuate-walled cells; ventral sporophylls with both surfaces greenish, comprising elongate, sinuate-walled cells. Megasporangia in 2 ventral rows or few and intermixed with microsporangia; megaspores yellow, mostly immature, rugulate-reticulate on proximal faces, reticulate on distal faces, microstructure not examined, ca. 200 µm. Microsporangia in 2 dorsal rows and on ventral rows or also in axil of median leaves immediately below strobili; microspores light orange, ornamentation and diameter not determined.

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.

The specific 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.

Selaginella stomatoloma is known only from three collections made in de Carajás National Forest, Brazil. This area is threatened by deforestation due to cattle ranching and large-scale mining (Pinheiro et al. 2012). Therefore, S. stomatoloma is considered Vulnerable (VU).

(paratypes). BRAZIL. Pará: Canaã dos Carajás, S11D, [ca. 06°23'08"S, 50°18'58.24"W], 23 May 2012, Salino et al. 15284 (BHCB, PMA), 27 Aug 2012, Salino et al. 15492 (BHCB, PMA).

The minute plant size, stomata along leaf margins (Fig. 10), and microsporangia in the axils of the median leaves near the strobili are features that Selaginella stomatoloma shares with S. saltuicola. They differ, however, by the characters discussed in the diagnosis.

Figure 10. 

Selaginella stomatoloma Valdespino. A Section of upper surface of stem B Upper surface of median leaf C Close-up of base and proximal portion of median leaf, upper surface; note marginal (a) and submarginal stomata (b) D Close-up of proximal portion and apex of median leaf, upper surface; note marginal (a) and submarginal (b) stomata E Section of lower surface of stem F Lower surface of lateral leaf; note marginal stomata (a) G Close-up of base and proximal portion of lateral leaf, lower surface; note marginal (a) and submarginal (b) stomata H Upper surface of lateral leaf. A–H taken from the holotype, Almeida et al. 2518 (PMA).

The presence of stomata along leaf margins seems to be a more common feature in Selaginella than previously realized. This 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 inefficient 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.

Figure 11. 

Selaginella trygonoides Valdespino. A Section of upper surface of stem B Upper surface of median leaf; note submarginal stomata (a) on inner half of the lamina C Close-up of inner margin of median leaf, upper surface; note submarginal stomata (a) D Close-up of median leaf upper surface; note papillae on cell lumen E Upper surface of median leaf; note submarginal stomata on inner half of the lamina F Close-up of base, portion of inner margin and inner half of lamina (note stomata), and portion of outer margin and outer half of lamina of median leaf, upper surface G Upper surface of lateral leaf and portion of median leaves, upper surface H Close-up of distal portion and apex of lateral leaf, upper surface. A–H taken from the holotype, Almeida et al. 1994 (PMA).

Figure 12. 

Selaginella trygonoides Valdespino. A Section of lower surface of stem B Lower surface of lateral leaf C Close-up of base and proximal portion of lateral leaf, lower surface; note marginal stomata (a) D Close-up of distal portion and apex of lateral leaf, lower surface E Lower surface of axillary leaf and portions of lateral leaves F Upper surface of lateral leaf G Close-up of base and proximal portion of lateral leaf, upper surface H Close-up of distal portion and apex of lateral leaf, upper surface; note marginal stoma (a). A–H taken from the holotype, Almeida et al. 1994 (PMA).

Selaginella trygonoides differs from the similar S. glazioviana Hieron. by having the upper surfaces of the leaves dull (vs. shiny due to thick waxy deposits covering cell walls), median leaf margins short-ciliate (vs. entire to denticulate) with the arista ½ (vs. usually ¼–⅓) the length of the lamina, and lateral leaves acuminate (vs. broadly acute to acute).

BRAZIL. Minas Gerais: Serra do Azeite, Pocrane, 19°30'12"S, 41°37'47"W, 300 m, 1 Jun 2009, T.E. Almeida, D.T. Souza & M.M.T. Cota 1994 (holotype: PMA! [PMA103371]; isotype: BHCB [BHCB130573]-n.v.).

Plants terrestrial or epipetric. Stems ascending to erect, stramineous, 3–5 cm long, 0.2–0.5 mm diam., non-articulate, not flagelliform or stoloniferous, 1- or 2-branched. Rhizophores axillary, borne on proximal ¼–½ of stems, filiform, 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 without 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 flap, each with a strongly developed and dentate keel along midribs, ovate to ovate-lanceolate, 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 flange, 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 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.

The specific epithet is derived from the Latin “trigon/trygonus”, meaning stingray; it alludes to the shape of the median leaf, which resembles these marine fish.

Selaginella trygonoides is known only from two collections made within or nearby populated areas; most likely it is subjected to anthropomorphic pressures. Thus, I tentatively consider it Vulnerable (VU).

(paratype). BRAZIL. Minas Gerais: Santa Rita do Itueto, Região da Cachoeira do Pontão, 19°24'52"S, 41°22'45"W, 185 m, 27 May 2009, Almeida et al. 1960 (BHCB-n.v., PMA).

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 conspecific with S. erectifolia Spring by Alston (1936), Reed (1965–1966), and Alston et al. (1981), but I consider these taxa to be distinct species (see discussion under S. glazioviana). Selaginella trygonoides differs 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. This collection is similar to S. trygonoides in having lateral leaves acuminate and median leaves aristate; however it differs 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.