Selaginella salinoi L.Góes & G.Heringer, 2015

Góes-Neto, Luiz Armando De Araújo, Heringer, Gustavo & Salino, Alexandre, 2015, Selaginella salinoi (Selaginellaceae), a new species from Brazil, Phytotaxa 224 (3), pp. 291-295 : 292

Selaginella salinoi L.Góes & G.Heringer , sp. nov. ( Figs. 1–2 )

Selaginella salinoi is morphologically similar to S. mucronata but differs by having lateral leaves with rounded (vs. hemicordate) bases and serrulate (vs. long-ciliate) margins; median leaves with margins denticulate throughout (vs. long-ciliate) and with obtuse to acute or rarely slightly cuspidate (vs. mucronate) apices; sporophylls with (vs. without) laminar flap.

Type: — BRAZIL. Espírito Santo: Divino de São Lourenço, Parque Nacional do Caparaó, Rio do Veado , 20˚33’07’’ S, 41˚45’44’’ W, 1190 m, 10 February 2011, F. S. Souza, L. L. Giacomin & T. M. Machado 1462 (holotype BHCB!; isotypes ALCB!, B!, CESJ!, UC!) .

Stems creeping, greenish to stramineous, 7–12 cm long, 0.5–0.6 mm diam., not articulate, not flagelliform, not stoloniferous, 1-branched when sterile, 2-branched when fertile. Rhizophores axillary, filiform, distributed along the stem. Leaves heteromorphic throughout, membranaceous, both surfaces glabrous, upper surfaces smooth, green to brownish, lower surfaces smooth, silvery green to brownish. Lateral leaves distant or slightly imbricate only toward apices, perpendicular to slightly ascending, ovate, 2.5–3.0 × 1.5–2.0 mm; bases rounded, acroscopic base overlapping the stem, basiscopic base not overlapping the stem; acroscopic margins hyaline, serrulate throughout, basiscopic margins narrowly hyaline, entire to serrulate along the basal third and serrulate toward apex; apices rounded or obtuse; upper surfaces with obscure idioblasts and stomata; lower surfaces with idioblasts and scattered stomata mainly on midribs. Median leaves distant or imbricate only at stem and branch apices, ascending, broadly ovate to ovate-elliptic or suborbicular near the branch apices, 1.6–2.2 × 1.4–1.8 mm; bases oblique; margins hyaline, denticulate throughout; apices obtuse to acute, or less frequent slightly cuspidate toward the branches apices; upper surfaces with conspicuous idioblasts and stomata; lower surfaces with a few obscure idioblasts and without stomata. Axillary leaves ovate; bases rounded; margins denticulate; apices rounded to obtuse; upper surfaces with obscure idioblasts and stomata; lower surfaces with idioblasts and scattered stomata mainly on midribs. Strobili terminal and lateral on branches, compact, 3– 8 mm long. Sporophylls slightly dimorphic; bases rounded; margins hyaline, serrulate; apices acute; dorsal sporophylls patent, ovate-lanceolate, 1.8–2.0 × 0.6–0.9 mm, with a conspicuous laminar flap and with a weakly developed and inconspicuously denticulate keel along midrib; upper surfaces green to dark green with few idioblasts and conspicuous stomata; lower surfaces silvery green to green; ventral sporophylls ascending, ovate, 1.5 × 0.8–1.0 mm, without a laminar flap or keel; upper surfaces sometimes slightly hyaline or usually pale green to silvery green with obscure idioblasts and with stomata. Megasporangia in two ventral rows; megaspores light yellow to cream when old; proximal face irregularly reticulate-granulate; distal face coarsely reticulate, with a slightly developed equatorial flange; 250 μm. Microsporangia in two dorsal rows; microspores orange; surfaces not examined; 25–35 μm.

Habitat and Distribution: —Known only from the type collection, in Parque Nacional do Caparaó, in Espírito Santo State. Growing on rocks in the Atlantic Rainforest at ca. 1200 m.

Etymology: —This species is named in honor of Dr. Alexandre Salino, for his outstanding contributions to pteridology, and especially for his guidance and training of several new Brazilian pteridologists.

Discussion: — Selaginella salinoi is characterized by ovate lateral leaves with rounded bases and rounded to obtuse apices, whose acroscopic portion overlapping the stem; further by median leaves which are broadly ovate to ovate-elliptic or near the branch apices suborbicular, and have denticulate hyaline margins, obtuse to acute or cuspidate apices, and upper surfaces with conspicuous idioblasts and stomata.

Selaginella salinoi is morphologically similar to the recently described S. mucronata , with which it shares the same habitat and geographical region. Both species have creeping stems, rhizophores distributed throughout stem length, and median leaves with stomata distributed throughout surface. However, S. salinoi has rhizophores always axillary (vs. ventral, axillary or dorsal); upper surfaces of leaves smooth (vs. corrugate); lateral leaves serrulate (vs. long-ciliate) with rounded (vs. hemicordate) bases; median leaves always distant (vs. imbricate) at the middle of stem, with denticulate (vs. long-ciliate) margins, acute to obtuse, or less frequent slightly cuspidate (vs. mucronate) apices; axillary leaves ovate (vs. commonly cordiform) with rounded (vs. cordiform) bases and denticulate (vs. long-ciliate especially on basal 1/2) margins; dorsal sporophylls with (vs. without) a conspicuous laminar flap; and megaspores subglobose to globose (vs. subtriangular).

Valdespino et al. (2015) included six South American species and one from southern Mexico in an informal Neotropical group of Selaginella , termed the “ Selaginella jungermannioides group”. Besides these seven species, S. mucronata (as highlighted by Valdespino et al. 2015) and S. salinoi may be part of this group, along with some other South American species (Góes-Neto, in prep.). Despite the authors having presented the main morphological characteristics of this group, more detailed morphological studies, as well as palynological and molecular studies are needed in order to characterize this species complex morphologically and test its monophyly.

Figures

FIGURE 1. Selaginella salinoi. A. Upper surface of stem showing distant median leaves. B. Upper surface of stem showing compact strobili and median leaves imbricate at branch apices. Photo by F.S. Souza.

FIGURE 2. SEM micrographs of Selaginella salinoi (F.S. Souza et al. 1462, BHCB). A. Upper surface of median and lateral leaves. B. Upper surface of median leaf. C. Lower surface of median leaf. D. Detail of upper surface of median leaf showing roundish cells, idioblasts, stomata, and denticulate margin. E. Lower surface of stem and lateral leaves. F. Lower surface of lateral leaf. G. Lower surface of axillary leaf with axillary rhizophore. H. Proximal face of megaspore. I. Detail of megaspore, proximal surface.