Selaginella pubimarginata Valdespino, 2020

Valdespino, Ivan A., 2020, Taxonomic innovations in South American Selaginella (Selaginellaceae, Lycopodiophyta): description of five new species and an additional range extension, PhytoKeys 159, pp. 71-113 : 71

Selaginella pubimarginata Valdespino sp. nov. Figures 9 , 10 , 11 , 12

Diagnosis.

Selaginella pubimarginata differs from S. albolineata by its ovate-deltate (vs. ovate to ovate-elliptic) lateral leaves with upper surfaces lacking (vs. with) conspicuous idioblasts, acroscopic margins long-ciliate along proximal ½, otherwise dentate to denticulate distally (vs. denticulate throughout), acute to attenuate to shortly acuminate (vs. obtuse to rounded) apices, and axillary leaves ciliate (vs. dentate) along proximal ½ -⅔.

Type.

Venezuela. Amazonas: Atabapo: Río Cunucunuma, entre las comunidades de Culebra y Huachamacari, entre el Cerro Duida y Huachamacari, 180-210 m, 03°40'N, 65°45'W, 28-30 Jan & 6-8 Feb 1982, J.A. Steyermark et al. 125655 (holotype: NY!; isotypes: MO!, NY!, PMA!, UC!).

Description.

Plants epipetric, terrestrial or epiphytic, moss-like. Stems creeping, stramineous, 2.0-12 cm long, 0.25-0.4 mm diam., not-articulate, not flagelliform or stoloniferous, straw-colored to brownish, 1- or 2-branched, the branches arising at ca. 45° angle. Rhizophores axillary, borne throughout the stems, filiform, 0.1-0.15 mm diam.

Leaves heteromorphic throughout, membranaceous, upper surfaces green, golden brown (in old leaves) or dark brown (in alcohol-preserved specimens), lower surfaces silvery. Lateral leaves distant, spreading, perpendicular to stems or less often slightly ascending, broadly ovate, ovate-deltate or ovate-elliptic, 1-1.5 × 0.5-1.2 mm; bases rounded, glabrous, acroscopic bases slightly overlapping stems, basiscopic bases free from stems; acroscopic margins on both surfaces plane or sometimes revolute on upper surfaces, along proximal ½ -⅔ bordered by a hyaline band comprised of idioblasts, the band 1-6 cells wide, the idioblasts elongate, straight-walled, and papillate, the papillae in a single or double row over each cell lumen, long-ciliate, otherwise on distal ⅓- ½, greenish, bordered by quadrangular to rounded cells, entire or sparse- and minutely denticulate, especially along distal ⅓, basiscopic margins on both surfaces greenish, bordered by quadrangular to rounded cells, entire throughout or sparse- and minutely denticulate, along distal ⅓; apices attenuate to shortly acuminate, each acumen ca. 0.1 mm long, tipped by 1-3 teeth; upper surfaces mostly glabrous, except for many, short, teeth-like hairs marginally to submarginally along basiscopic margins and distally towards and at the apices, comprising rounded to quadrangular, slightly sinuate, and broad-walled cells on basiscopic ⅔ of the laminae, the cells papillate, the papillae 1-5 and irregularly arranged on each cell lumen, on acroscopic ⅓ of the laminae comprising strongly sinuate, thin-walled, and glabrous cells, without idioblasts, stomata present on acroscopic margins along distal ⅓ and on basiscopic margins along distal ¾, lower surfaces glabrous, comprised of elongate, sinuate-walled, laevigate cells and of straight-walled, papillate idioblasts, the papillae 7-28 in one or two rows on each cell lumen, the idioblasts evenly distributed on the laminae and strongly grouped on proximal, basal region of the laminae, with stomata on 1-5 rows along midribs. Median leaves distant to slightly imbricate near branch tips, ascending, broadly elliptic to orbicular or broadly ovate-elliptic with both inner and outer halves equal in width, 0.7-1.2 × 0.5-0.8 mm; bases glabrous, oblique, not decurrent, without auricles; margins plane or outer margins on proximal ¼ revolute, along proximal ½ bordered by greenish, quadrangular cells, on distal ½ bordered continuously by a narrow hyaline band comprised of idioblasts, the band 1 or 2 cells wide, the idioblasts similar to those in the hyaline marginal bands of proximal ½ -⅔ of acroscopic margins of the lateral leaves, dentate on outer margins and short-ciliate along proximal ½, otherwise dentate along distal ½ on inner margins; apices short acuminate, each acumen 0.1 or 0.2 mm long and tipped by 1-3 teeth; upper surfaces glabrous, except for few, submarginal, short, teeth-like hairs on mid portion of outer margins, comprised of round to quadrangular slightly sinuate, thick-walled, papillate cells and one, papillate idioblast along mid-section of outer margins, the papilla 10-13 on a single row on each cell lumen, stomata on midrib along distal ½ and submarginally to marginally along proximal ½ of outer margins, lower surfaces glabrous, comprised of elongate, sinuate-walled, laevigate cells, without stomata. Axillary leaves broadly ovate, ovate-deltate or ovate-elliptic, 1.2-1.6 × 0.7-1.2 mm; bases attenuate; margins bordered continuously by a hyaline band comprised of papillate idioblasts along proximal ⅔, the band 1-6 cells wide, the papillae in a single row, on distal ⅓ bordered by greenish, quadrangular cells, long-ciliate along proximal ½ -⅔, otherwise entire to denticulate distally; apices attenuate, each 0.1 mm long, tipper by 1-5 teeth. Strobili terminal, loosely quadrangular, 1.5-9 mm long. Sporophylls monomorphic, without a laminar flap, each with a slightly developed keel along midribs, the keel puberulent with short, tooth-like projections distally, ovate to ovate-lanceolate, (0.6)0.9-1.5 × (0.3)0.5-0.7 mm; bases rounded; margins obscurely hyaline bordered by 1-3(4) elongate, papillate idioblasts (especially apically), serrate; apices long-acuminate, tipped by 1-3 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 greenish hyaline to hyaline with elongate and slightly sinuate-walled cells, lower surfaces hyaline and comprising elongate, sinuate-walled cells; ventral sporophylls with both surfaces, hyaline, comprised of elongate, papillate, sinuate-walled cells. Megasporangia few and proximal, along two ventral rows; megaspores light to lemon-yellow, 240-250 µm diam., proximal faces rugulate with a slightly developed equatorial flange, the microstructure sparsely, short echinate and perforate, distal faces rugulate to reticulate, the rugulae or reticulae open (incomplete) to closed, each reticulum with low walls, the microstructure sparsely, short echinate and perforate. Microsporangia light orange in two dorsal rows and distally along two ventral rows; 22-250 µm diam., microspores light orange, rugulate on proximal and distal faces, with the microstructure perforate.

Habitat and distribution.

Selaginella pubimarginata grows on shaded or exposed moist boulders, along streambeds, and waterfalls in tropical rainforests at 80-700 m; it is known at and around Cerro Huachamacari, along the rivers Sipapo and Coromoto in Amazonas state, and along Río Caura in Bolívar state, Venezuela.

Etymology.

The epithet derives from the Latin " puberulus," slightly pubescent, and " marginatus," having a border. Together these refer to the presence of submarginal hairs on lateral leaves upper surfaces near the basiscopic and apical portion of leaf laminae.

Conservation status.

Selaginella pubimarginata is known from four collections made in two states in the Guiana Highland region of Venezuela. Current available data, however, is scanty and does not allow for a reliable conservation assessment. Accordingly, this new species is considered Data Deficient (DD) based on IUCN (2012).

Additional specimens examined (paratypes).

Venezuela. Amazonas. Atabapo: Cerro Huachamacari, E slope, 03°49'N, 65°42'W, 600-700 m, 2 Nov 1988, Liesner 25697 (MO, UC); Río Cunucunuma, entre las comunidades de Culebra y Huachamacari, entre el Cerro Duida y Huachamacari, 03°40'N, 65°45'W, 180-210 m, 28-30 Jan & 6-8 Feb 1982, Steyermark et al. 125639 (NY, UC), 200-400 m, 28-30 Jan & 6-9 Feb 1982, Guariglia et al. 1676 (NY-2 sheets); Atures: 125 km de la boca (delta) del Guayapo en Sipapo, 04°22'N, 67°06'W, 130 m, May 1989, Foldats & Velazco 9203 (NY); 40 km S of Puerto Ayacucho, Tobogán de la Selva, 05°35'N, 67°30'W, 70-100 m, 21 Jan 1985, Beitel & Buck 85010 (NY, UC); Río Coromoto, above Tobogán de la Selva, 35 km SE of Puerto Ayacucho, 05°27'N, 67°33'W, 80 m, 7 Sep 1985, Steyermark et al. 131528 (MO, UC). Bolívar: alrededor del campamento "Las Pavas", vecindad del Salto Para, Río Caura (lado derecho del río abajo), 230-280 m, 15-17 Jan 1977, Steyermark et al. 112992 (GH, MO); Medio Caura, selva del Salto de Para, 300 m, 5 Mar 1939, Williams 11385 (BM, F).

Discussion.

Selaginella pubimarginata is characterized by its moss-like habit, lateral leaf ovate-deltate, with tooth-like, short hairs on the upper surfaces along basiscopic halves of leaf laminae, long-ciliate margins along proximal ½, and acute to attenuate to shortly acuminate apices, axillary leaves similar in overall shape and apices to lateral leaves and long-ciliate margins along proximal ½.

Selaginella pubimarginata belongs in the " Selaginella deltoides group", and among species in this alliance it is morphologically close to S. albolineata and S. papillosa . It is set aside from S. albolineata by characters listed in the diagnosis. Selaginella pubimarginata is distinct from S. albolineata by its axillary leaves ovate-deltate (vs. ovate-elliptic) with acute to attenuate to shortly acuminate (vs. obtuse to rounded) apices, lateral leaf upper surfaces without (vs. with many) idioblasts, and median leaf upper surfaces with a single, elongate and papillate idioblast on either the outer or inner halves of the laminae (vs. with two or three, elongate, and papillate idioblasts on the outer and inner halves of the laminae). Selaginella pubimarginata differs most noticeable from the also similar S. papillosa by its median leaf upper surfaces with a single (vs. lacking) elongate and papillate idioblasts on either the outer or inner halves of the laminae, with (vs. lacking) one or two, teeth-like hairs on mid, submarginal portion of the outer half of the laminae, and laminae comprised of rounded, sinuate-walled cells with the cell lumina including 1-5 (vs. 4-15) rounded (vs. conical) and not protruding (vs protruding or elevated) papillae, as well as apices covered by (vs. without) teeth-like, short hairs. In addition, the lateral leaf upper surfaces of S. pubimarginata are covered by many (vs. few) ca. 40 (vs. 3-5) short hairs or teeth-like projections along submarginal portion of basiscopic margins and on distal, apical portion (vs. concentrate on distal most portion) of apices. Finally, S. pubimarginata is further distinct from S. papillosa by its rugulate (vs. rugulate-reticulate) megaspores on proximal faces with a slightly developed (vs. with a well-developed) equatorial flange, with microstructure sparsely (vs. abundantly) covered by short- (vs. long-) echinae and distal faces slightly (vs. strongly) reticulate with open (vs. with open and closed) reticulae delimited by low (vs. high) muri.

All specimens of S. pubimarginata here cited were previously identified either as S. brevifolia or S. brevifolia vel aff. Selaginella pubimarginata is set aside from S. brevifolia by its median leaf ovate-orbicular to orbicular (vs. ovate) with the laminae almost as wide as long (vs. longer than wider) with outer and inner leaf halves about the same width (vs. outer leaf half frequently wider than the inner leaf half), attenuate to shortly acuminate (vs. long-aristate) apices, each acumen ⅕- ¼ (vs. ⅓- ½) the length of the leaf lamina, and margins obscurely hyaline or greenish (vs. conspicuously hyaline, especially the outer margin). Selaginella pubimarginata differs further from S. brevifolia by its lateral leaf upper surfaces when viewed with a dissecting scope with midribs not marked and of the same color as the laminae (vs. well-marked and straw-colored) and laminae epidermal cells inconspicuously (vs. conspicuously) rounded, and long-ciliate along proximal ½ (vs. ½-¾) margins.

Figures

Figure 9. Distribution of Selaginella papillosa *, S. pubimarginata ◊, S. rostrata ■.

Figure 10. Selaginella pubimarginata Valdespino. A Section of upper surface of stem showing median and lateral leaves B median leaf, upper surface C distal half of median leaf, upper surface (same leaf shown in B) D proximal half of median leaf, upper surface (same leaf shown in B) E section of median leaf outer half, upper surface; note prominent elongate, papillate idioblast (a) and submarginal stomata (b) F detail of midsection of inner half of median leaf, upper surface G detail of median leaf, upper surface; note papillate cells H lateral leaf, upper surface I section of proximal, acroscopic half of lateral leaf, upper surface (same leaf shown in H) J section of distal and basiscopic half of lateral leaf, upper surface (same leaf shown in H) K detail of section of basiscopic margin of lateral leaf, upper surface (same leaf shown in H); note submarginal stomata (a) and teeth-like hairs (b) L detail of lateral leaf, upper surface; note papillate cells. A-L taken from the holotype.

Figure 11. Selaginella pubimarginata Valdespino. A Section of lower surface of stem showing lateral and median leaves and axillar leaf B lateral leaf, lower surface C proximal half of lateral leaf, upper surface (same leaf shown in B) D section of proximal acroscopic margin and base of lateral leaf, lower surface (same leaf shown in B); note elongate, papillate idioblasts (a) E distal half of lateral leaf, lower surface (same leaf shown in B); note elongate, papillate idioblasts (a) F mid-section of lateral leaf, lower surface (same leaf shown in B); note elongate, papillate idioblasts (a) and stomata along midrib (b) G axillary leaf (a) and portions of lateral and median leaves, lower surfaces H detail of outer half of median leaf (a) and axillary rhizophores (b), lower surfaces (same leaf shown in G). A-H taken from the holotype.

Figure 12. Selaginella pubimarginata Valdespino. A Megaspore, proximal face B detail of megaspore, proximal face C megaspore, distal face D detail of megaspore, distal face E microspore, proximal face F detail of microspore, proximal face G microspore, distal face H detail of microspore, distal face. A-H taken from the holotype.