Selaginella mucugensis Valdespino, 2015

Valdespino, Ivan A., Heringer, Gustavo, Salino, Alexandre, Goes-Neto, Luiz A. de Araujo & Ceballos, Jorge, 2015, Seven new species of Selaginella subg. Stachygynandrum (Selaginellaceae) from Brazil and new synonyms for the genus, PhytoKeys 50, pp. 61-99 : 72-73

Selaginella mucugensis Valdespino sp. nov. Figures 10 , 11

Diagnosis.

Selaginella mucugensis differs from Selaginella blepharodella in having median leaves distant (vs. imbricate), ovate (vs. broadly-ovate to ovate-elliptic), with margins hyaline in a band 2-5 (vs. 5-15) cells wide with cilia 30-50 (vs. 130-180) µm long, stomata on upper surfaces on submarginal and marginal regions of the outer bases (vs. restricted to midribs), apices acute to short-acuminate (vs. long-acuminate), the acumen, if present, 0.02-0.08 (vs. acumen 0.1-0.3) mm, and lateral leaves with basiscopic margins entire along proximal ¼-½ and serrate to short-ciliate distally (vs. usually ciliate throughout).

Type.

BRAZIL. Bahia: Mucugê, campo defronte ao cemitério, [ca. 13°00'S, 41°22'19"W], [ca. 984 m], 20 Jul 1981, A.M. Giulietti et al. [CFCR 1430] (holotype: NY!; isotypes: PMA- fragment!, SPF-n.v.).

Description.

Plants terrestrial. Stems ascending to suberect, stramineous, 3-7 cm long, 0.2-0.4 mm diam., exarticulate, not flagelliform, probably shortly stoloniferous, 2- or 3-branched. Rhizophores axillary and axillary-dorsal, restricted to the bases of stems, filiform, 0.1-0.2 mm diam. Leaves heteromorphic throughout, chartaceous, both surfaces glabrous, upper surfaces green, lower surfaces silvery green or brownish (when old). Lateral leaves distant, slightly ascending, ovate to slightly ovate-oblong, 1.2-1.5 × 0.9-1.1 mm; bases rounded, acroscopic bases slightly to strongly overlapping stems, basiscopic bases free from stems; acroscopic margins hyaline in a band 2-8 cells wide, the cells elongate and papillate parallel to margins, papillae in 1 row over each cell lumen, long- to short-ciliate along proximal ¾ and serrate to entire along distal ¼; basiscopic margins narrowly hyaline or greenish in a band 1 or 2 cells wide, the cells as along acroscopic margins, entire along proximal ¼-½ and serrate to short-ciliate distally, apices acute, tipped by 1-3 teeth; upper surfaces comprising rounded to quadrangular, sinuate-walled cells, some of these covered by 4-8 papillae, without idioblasts or stomata, lower surfaces comprising elongate, sinuate-walled cells, some of these papillate and idioblast-like, papillae in 2 rows over each cell lumen, with stomata in 2 or 3 rows along midribs and along proximal ½ of basiscopic margins. Median leaves distant, ascending, ovate, 0.8-1.3 × 0.5-0.7 mm; bases oblique, inner bases plane in profile, outer bases ventricose (i.e., swollen); margins hyaline in a band 2-5 cells wide, the cells elongate and papillate parallel to margins, papillae in 1 row over each cell lumen, shortly ciliate throughout; apices acute to short-acuminate, each acumen 0.02-0.08 mm, occasionally with 1 or 2 hairs on upper surfaces, tipped by 1-3 teeth; both surfaces without idioblasts, upper surfaces comprising rounded to quadrangular, sinuate-walled cells covered by 4-8 papillae, with stomata along midribs and some on submarginal and marginal regions of the outer bases, lower surfaces comprising elongate, sinuate-walled cells, without stomata. Axillary leaves similar to lateral leaves. Strobili terminal on branch tips, compact, quadrangular, 2.0-7.0 mm. Sporophylls monomorphic, without a laminar flap, ovate, 0.8-1 × 0.4-0.5 mm, each with a well-developed, frequently puberulous keel along the midribs; bases rounded; margins hyaline, short-ciliate to serrate; apices acute, 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, there 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 frequently proximal in 2 ventral rows or the proximal megasporangia abortive and a few intermixed with microsporangia; megaspores lemon-yellow, mostly immature or absent, proximal faces not observed, reticulate on distal faces, 275-285 µm. Microsporangia in 2 dorsal rows and, in distal portion, also in 2 ventral rows; microspores orange, gemmate-rugulate or broadly baculate-rugulate with psilate to echinulate microstructure on proximal faces, vermiculate with echinulate microstructure on distal faces, 30-40 µm.

Habitat and distribution.

Selaginella mucugensis is known only from the type collection from Mucugê, Serra do Sincorá, in the Chapada Diamantina region of the Espinhaço Mountain Range, where it is probably a local endemic. It grows terrestrially on damp soil in Campos Rupestres vegetation at ca. 984 m.

Etymology.

This species is named for the type locality.

Conservation status.

At present, there is limited information available to allow a conclusive determination of the conservation status of Selaginella mucugensis . Nevertheless, according to IUCN (2012) categories and criteria, we tentatively considered this species to be vulnerable (VU) on account that it is so far known from a single locality in the Espinhaço Mountain Range, which is threatened by human activities ( Rapini et al. 2008).

Discussion.

Selaginella mucugensis is a member of subg. Stachygynandrum and may be confused with Selaginella blepharodella because they have similar leaf margins and indument on the upper surfaces in the distal region of median leaves and sporophylls (Fig. 7B ). In fact, these two species may prove to be sympatric in the Serra do Sincorá, where both were collected. According to Harley and Simmons (1986), this area is an important center of diversity of the Brazilian montane flora. Selaginella mucugensis is distinguished from Selaginella blepharodella by the characters discussed under the diagnosis.

Figures

Figure 7. Selaginella crinita Valdespino. A Megaspore proximal face B Close-up of megaspore proximal face surface C Megaspore distal face D Close-up of megaspore distal face surface E Microspore proximal face F Microspore distal face A-F taken from holotype, Harley & Taylor 27048 (NY).

Figure 10. Selaginella mucugensis Valdespino. A Section of upper surface of stem B Upper surface of median leaf C Section of lower surface of stem D Lower surface of lateral leaf A-D taken from holotype, Giulietti et al. [CFCR 1430] (NY).

Figure 11. Selaginella mucugensis Valdespino. A Microspore proximal face B Close-up of microspore proximal face surface C Microspore distal face D Close-up of microspore distal face surface A-D taken from holotype, Giulietti et al. [CFCR 1430] (NY).