Selaginella phiara Valdespino, C. López & L. Góes, 2014

Valdespino, Iván A., López, Christian & De Araújo Góes-Neto, Luiz A., 2014, Additions to Cuban Selaginella (Selaginellaceae), Phytotaxa 184 (4), pp. 235-244 : 242-243

Selaginella phiara Valdespino, C. López & L. Góes , sp. nov. ( Fig. 5 )

Selaginella phiara differs from S. armata Baker (1884: 90) by acuminate to short-aristate (0.2–0.3 mm) median leaves (vs. long-aristate, 0.4–0.5 mm) and upper surface of median and lower surface of lateral leaves or at least one of them usually with conspicuous idioblasts (vs. without).

Type: — CUBA. Isla de Piñas [Isla de Pinos — Isla de la Juventud special municipality]: Sierra de Las Casas , 200 m, 22 March 1916, N . Britton & P . Wilson 15754 (holotype NY!, isotypes HAJB!, PMA!, US!).

Plants terrestrial or epipetric. Stem postrate, short-creeping, stramineous, 3–10 cm long, 0.5–0.8 mm diam., inarticulate, not flagelliform or stoloniferous, 2 or 3-branched. Rhizophores axillary, borne throughout stem, 0.1–0.3 mm diam. Leaves dimorphic throughout, chartaceous. Lateral leaves distant to imbricate, spreading, ovate to oblong-lanceolate, 1.8–2.2 × 1.0– 1.3 mm; base rounded or truncate, acroscopic base overlapping the stem, basiscopic base free from the stem; acroscopic margin hyaline, 2–5 cells wide, the cells elongate and papillate parallel to margin, papillae in a single row over cell lumen, with long cilia (0.1–0.3 mm) along basal ½, otherwise shortly ciliate (0.05–0.1 mm) to serrate apically, basiscopic margin hyaline, 1–3 cells wide, the cells elongate and papillate parallel to margin, papillae in a single row over cell lumen, with cilia (0.1–0.2 mm) along basal ½, otherwise serrate; apex acute to cuspidate (0.1–0.2 mm) tipped by 1–3 teeth; both surface glabrous, upper surface, made up of rounded to quadrangular, sinuate-walled cells without stomata and idioblasts, lower surface made up of elongated, sinuate or straight-walled cells, with stomata along midrib and papillate idioblasts. Median leaves imbricate, ascending, narrowly ovate to ovate-lanceolate, 1.0–1.2 × 0.3–0.4 mm; base oblique, inner base overlapping the stem, outer base free from stem; margins hyaline made up of 1–3 cells wide, the cells elongate and papillate parallel to margins, papillae in a single row over cell lumen, ciliate (0.1–0.2 mm) throughout, apex acuminate or short aristate, acumen or arista 0.2–0.3 mm long, with short hairy projections on upper side and tipped by 2–4 teeth, both surfaces glabrous, upper surface made up of quadrangular to rounded, sinuate-walled cells, with stomata along midrib and on submarginal region of outer base and with papillate idioblasts, lower surface made up of elongated, sinuate or straight-walled cells, without stomata and with obscure, papillate idioblasts. Axillary leaves similar to lateral leaves. Strobili terminal on branch tips, one per branch, loosely quadrangular to slightly flattened, 1.0–6.0 mm long. Sporophylls monomorphic, without a laminar flap, ovate, 1.0– 1.5 × 0.3–0.6 mm, with a well-developed serrate keel along midrib; base rounded; margins hyaline, ciliate (0.1–0.2 mm) throughout; apex acuminate (0.1–0.3 mm); both surfaces with idioblasts; dorsal sporophylls with upper surface greenish, except for the half that is overlapping the ventral sporophylls where it is hyaline, lower surface greenish; ventral sporophylls with both surfaces greenish-hyaline. Megasporangia in two ventral rows; megaspores buff or pale cream, proximal face rugose with slightly echinate microstructure, distal face reticulate with slightly echinate microstructure, 285–300 µm diam. Microsporangia in dorsal rows; microspores orange, proximal face rugose, distal face baculate, 27–30 µm diam.

Habitat and Distribution: — Cuba; terrestrial or epipetric; 0–671m.

Etymology: — The specific epithet is derived from the Greek phiaros, meaning shining, bright; referring to the bright papillae on leaf idioblasts.

Conservation Status: — The paucity of data does not allow ascertaining abundance and possible threats to this species and, therefore, we assign to it a Data Deficient (DD) conservation assessment according to IUCN (2012) categories and criteria.

Additional Specimens Examined (Paratypes): — CUBA. Isla de Pinos [Isla de la Juventud special municipality]: Vicinity of Los Indios, 13 February 1916, Britton et al. 14260 ( NY), Nueva Gerona, 1 July 1900, Palmer & Riley 944 ( S), 8 July 1900, Palmer & Riley 1035 (US) , May 1904, Curtiss s.n. ( B, NY, US) , along road to San Francisco de las Piedras, 23 December 1955, Killip 45250 ( US) , about 2 km southeast of Santa Fe , 18 March 1954, Killip 43634 ( US) , McKinley road, about 2 km west of Nueva Gerona, 1 February 1955, Killip 44644 ( US) , Isla de la Juventud, from Nueva Gerona on road to Santa Fe , 21º48’01”N, 82º47’28”W, 16 November 2012, Thomas et al. 15984 ( NY, PMA), Sierra Las Casas , 18 October 1920, Ekman 11719 ( S). Pinar del Río: Sierra Mendoza, [671 m], 25 December 1911, Shafer 11150 ( US) .

Discussion: — Selaginella phiara usually has conspicuous idioblasts on both surfaces of the sporophylls and on the upper surface of median and on lower surface of lateral leaves, which have several bright, interconnected, papillalike projections ( Fig. 5 ), as well as short hairy projections on the upper surface of median leaf apex ( Fig. 5C ). Selaginella phiara somewhat resembles S. armata , but they can be separated by the characters given in the diagnosis.

Another Cuban species, Selaginella urquiolae , has leaf idioblasts also, but it is a more robust plant. Selaginella phiara differs further from S. urquiolae by having the upper surface of lateral leaves glabrous (vs. hairy near basiscopic margin), ovate to oblong-lanceolate (vs. deltate-ovate to ovate-oblong), 1.8–2.2 mm long (vs. 2.6–3.5 mm) and median leaves ovate to ovate-lanceolate (vs. broadly ovate to ovate-elliptic), 1.0–1.2 × 0.3–0.4 mm (vs. 1.6–2.5 × 0.6–1.1 mm), and apices tipped by an acumen or short arista 0.2–0.3 mm long (vs. 0.5–0.7 mm).

Figures

FIGURE 5. SEM micrographs of stem and leaves of Selaginella phiara (Britton & Wilson 15754, NY). A. Upper surface of stem. B. Upper surface of median and lateral leaves; note papillate idioblasts on median leaf. C. Detail of median leaf apex showing roundish cells, stomata, papillate idioblasts, and stiff, short hairs on tip. D. Lower surface of stem. E. Lower surface of lateral leaf showing idioblasts. F. Detail of lateral leaf showing elongate, sinuate-walled cells, papillate idioblasts, and marginal, elongate and papillate cells.