Selaginella philipsonii (Jermy & Rankin) Valdespino, comb. et, 2017

Valdespino, Ivan A., 2017, Novel fern- and centipede-like Selaginella (Selaginellaceae) species and a new combination from South America, PhytoKeys 91, pp. 13-38 : 22-24

Selaginella philipsonii (Jermy & Rankin) Valdespino, comb. et stat. nov. Figure 11

Selaginella philipsonii (Jermy & Rankin) Valdespino≡ Selaginella ovifolia Baker, subsp. philipsonii Jermy & Rankin, Bull. Brit. Mus. (Nat.Hist.) 9(4): 294. 1981. Type: Colombia. Meta / Vaupés: Sierra de la Macarena, Río Guapaya, 03°38'50.72"N, 72°50'45.05"W, 450 m, 29 Nov 1949, W.R. Philipson, J.M. Idrobo & A. Fernández 1607a (holotype: BM barcode BM000905679!).

Description.

Plants terrestrial or epipetric. Stems creeping, stramineous, 6-10 cm long, 0.2 to 0.3 mm diam., non-articulate, not flagelliform, not stoloniferous, 1-branched. Rhizophores axillary and dorsal throughout the stems, filiform, 0.05-0.1 mm diam. Leaves dimorphic, chartaceous. Lateral leaves imbricate, ascending to spreading, ovate, ovate-elliptic or ovate-oblong, (1.0)1.2-1.7 × 0.6-1.2 mm; bases rounded, acroscopic bases overlapping the stem, basiscopic bases free from the stem; acroscopic margins on upper surfaces greenish to greenish hyaline, made up of a band 1 or 2 cells wide, the cells elongate and papillate, parallel to margins, the papillae in one or two rows over each cell lumen, on lower surfaces hyaline, made up of a band 3-5 cells wide, the cells elongate and papillate, parallel to margin, the papillae in one or two rows over each cell lumen, long-ciliate throughout, the hairs long on proximal ¾ and distally smaller, basiscopic margins on upper and lower surfaces greenish, made up of a band 1 or 2 cells wide, the cells elongate and glabrous, parallel to margins, sparsely short-ciliate throughout or seemingly denticulate along proximal ¾ and with short hairs along distal ⅓ and with marginal stomata along proximal ½; apices obtuse to broadly acute or acute, tipped by (1) 2 (4), often divergent, long cilia; upper surfaces with elongate, idioblast-like cells at the base, the idioblasts papillate, the papillae in two rows, otherwise idioblast absent, most of the surface made up of irregular, quadrangular to rectangular, irregularly-walled, papillate cells, the papillae 9-15 irregularly arranged over each cell lumen or some cells glabrous, especially toward basiscopic bases, the laminae pubescent near basiscopic margins, the midrib not prominent, without stomata, the lower surfaces glabrous, made up of elongate, straight-walled, idioblast-like and papillate cells, the papillae 10-30 over each cell lumen, arranged in 2 or 3 rows and often interconnected, midrib not raised or prominent, with stomata in 2 or 3 rows concentrated along raised portion of midrib. Median leaves imbricate, ascending, narrowly lanceolate to narrowly lanceolate-elliptic, 0.5-1.2 × 0.3-0.6 mm; bases oblique to obtuse, glabrous; the inner margins broadly hyaline, made up of a band 2-7 cells wide, the cells elongate, idioblast-like, papillate and parallel to margins, papillae in 1 or 2 rows over each cell lumen and some of these interconnected, proximally entire and short-ciliate along distal ⅔, the outer margins greenish, made up of 2 or 3 elongate and glabrous cells and with the submarginal portion of the lamina conspicuously hyaline, made up of a band of 8-12 cells wide, the cells elongate, idioblast-like, papillate and parallel to the margins, papillae in 1 or 2 rows over each cell lumen and some of these interconnected; apices acute, attenuate to shortly acuminate, tipped by 1-5 long, divergent cilia or more often by two long, divergent cilia, the acumen or arista 0.1-0.3 mm long; both surfaces without idioblasts, except for the outer margins that have similar hyaline and papillate cells as the inner margins and submarginal portion of outer margins on the upper surfaces, the upper surfaces glabrous, made up of similar cells as the upper surfaces of the lateral leaves, the midrib not prominent and difficult to observe, stomata few, on a single row along distal ½ of each lamina, the lower surfaces glabrous, made up of elongate, straight-walled and papillate cells, papillae 10-30 over each cell lumen, arranged in 2 or 3 rows and often interconnected, midrib on lower surfaces not raised or prominent, stomata absent. Axillary leaves absent or, if seemingly present, corresponding to lateral leaves. Strobili terminal and single on branch and stem tips, quadrangular, 1.5-6.0 mm long. Sporophylls monomorphic, without a laminar flap, ovate-lanceolate, 0.8-1.2 × 0.5-0.6 mm, with a well-developed, puberulent to shortly ciliate keel along midribs on upper surfaces; bases rounded; margins hyaline, dentate to minutely ciliate; apices acuminate, the acumen 0.1-0.3 mm long; both surfaces without conspicuous idioblasts, glabrous; dorsal sporophylls with upper surfaces green, except for the halves that overlap the ventral sporophylls where they are hyaline, lower surfaces hyaline; ventral sporophylls with both surfaces hyaline. Megasporangia along distal ⅛ of ventral and dorsal rows; megaspore light- to deep yellow, proximal and distal faces smooth to slightly rugulate, the microstructure not observed, 180-200 μm diam. Microsporangia on ventral and dorsal rows along proximal ⅜; microspores deep orange, the ornamentation not observed, not measured.

Habitat, distribution and phenology.

Selaginella philipsonii grows on soil, wet slopes, wet rocks along riverbanks or on shaded bluffs; 100-600 m; it is known from the Meta Department of Colombia and in the State of Mérida, Venezuela and found fertile from February through to November.

Conservation Status.

Selaginella philipsonii was sporadically collected from 1949 through to 1981 in the Amazon basin of Colombia and Venezuela. No recent collections were seen. This could be, however, due to its being a minute and easily overlooked species. Consequently, based on the lack of reliable information to assign a conservation status, it is considered Data Deficient (DD), according to IUCN (2012) categories and criteria.

Additional specimens examined.

COLOMBIA. Casanare: Tauramena , 600 m, 13 Apr 1963, Uribe Uribe 4290 (US) . Guaviare: San Jose del Guariare [Guaviare], s.d., Schultes 11120 (GH) . Meta: Caño Piedra de Candela, 5 km from Remolino, 13 Feb 1969, Pinto & Sastre 841 (COL, P), Rio Guayabero , 10 km below Caño Lozada, 350 m, 18 Jan 1959, Pinto & Bischler 239 (COL [digital image]) . Vaupés: Angostura No. 2, Rio Guayabero , 23 Feb 1969, Pinto & Sastre 1024 (COL) . VENEZUELA. Mérida: on slope above dam site on Río Caparo, 31 km ESE of Santa Barbara, 07°41'N, 71°28'W, 100-250 m, 9 Mar 1980, Liesner & González 9263 (F, PMA); 2-4 km above dam site on Rio Guaimaral , 07°45'N, 71°29'W, 200-400 m, 16 Mar 1981, Liesner & González 10648a (MO) . Tachira: W of Ayarí, 200 m, 21 Aug 1966, Steyermark & Rabe 96652 (GH), along old highway, W of Ayarí, 07°32'N, 71°53'W, 250 m, 7 Nov 1979, Steyermark et al. 119488 (MO, UC) .

Discussion.

Selaginella philipsonii was originally described as a subspecies of S. ovifolia by Jermy and Rankin in Alston et al. (1981: 294). They indicated, however, that Alston considered it a new species, a conclusion with which the author fully concurs and hence its recognition here at that level. According to Alston (1955: 244), S. ovifolia is a taxon found in the Dominican Republic, Haiti, Jamaica, Puerto Rico and Belize. Certainly, these two taxa share a moss-like habit and median leaf apices ending in long cilia. Nevertheless, S. philipsonii is most distinguished by the median leaves on main stems imbricate, oblong-elliptic with the inner margins hyaline, made up of a band of 2-7, elongate and papillate cells and shortly ciliate and the outer margins greenish, made up of 2 or 3 elongate and glabrous cells and the submarginal portion of the laminae conspicuously hyaline, composed of a band of 8-12 cells wide, with the cells elongate and papillate, parallel to the margins, the papillae in 1 or 2 rows over each cell lumen and some of these interconnected (see Figs 11A-D , 16B in Alston et al. 1981: 296), entire and the apices acute, attenuate to shortly acuminate, tipped by 1-5 (Fig. 11C ) or often 2 long, divergent cilia, the acumen or arista 0.1-0.3 mm long. It is further characterized by the lateral leaves acroscopic margins long-ciliate, the basiscopic margins denticulate, the apices obtuse to broadly acute or acute, tipped by (1) 2 (4), often divergent, long cilia (Fig. 11E-G ). In addition, SEM images of the median leaves show stomata along the outer margins, as well as on the midribs (Fig. 11B-D ). Conversely, S. ovifolia is characterized by median leaves on main stems distant, elliptic to ovate-elliptic, the margins sparingly short- to long-ciliate, having the outer margins and the outer submarginal portion of the laminae greenish, composed of rounded cells or the outer margins only slightly hyaline on distal ¼ and made up of only 1 or 2 elongate and papillate cells, while the inner margins are greenish, comprised of roundish cells, the apices long-acuminate, tipped by 2 long cilia, the lateral leaf acroscopic margins long-ciliate, while the basiscopic margins are short- to long-ciliate and the apices acute or short- to long-acuminate, tipped by 1-3 teeth or short cilia.

Jermy and Rankin in Alston et al. (1981: 294) cited two specimens from Norte de Santander: Catatumbo, Campo Oru, 08°30'30"N, 73°15'52"W, 350-500 m, 13 May 1959, Bischler 2397 (COL!) and Campo Tibú, Río Tibú, 08°28'19"N, 72°55'08"W, 200 m, 16 May 1959, Bischler 2493 (COL!) as S. ovifolia subsp. philipsonii . These specimens, however, have soboliferous stems, median leaves narrowly elliptic to ovate-lanceolate, 0.3-0.6 × 0.15-0.3 mm with the inner and outer margins dentate to shortly ciliate, the outer margins and the submarginal portion of the laminae greenish, made of rounded cells or the outer margins only slightly hyaline composed of only 1-3 elongate cells and puberulent bases with 1-3 stiff, short hairs or tooth-like projections. Therefore, the author believes it is best to exclude those specimens from S. philipsonii .

Selaginella philipsonii is morphologically close and may be confused with S. homaliae A. Braun and S. schultesii Alston ex Crabbe & Jermy, which are both from South America, because of their moss-like habit, slender rhizophores, minute leaves and keeled sporophylls with the keel short-ciliate to dentate. Selaginella philipsonii differs noticeably from S. homaliae and S. schultesii by its median leaf outer margins greenish (vs. conspicuously hyaline) with the submarginal portion of the laminae conspicuously hyaline (vs. greenish), which is made up of a band of 8-12 elongate and papillate (vs. composed of roundish and glabrous) cells that are parallel to the margins, the apices acute, attenuate to shortly acuminate, tipped by 1-5 (Fig. 11C ) or often 2 long, divergent cilia (vs. apices aristate, denticulate with the tip gradually tapering into a long arista and tipped by 1-3 teeth in S. schultesii and mucronate to shortly acuminate and tipped by 1 or 2 teeth in S. homaliae ) and the outer margins entire (vs. long-ciliate in S. schultesii and short-ciliate in S. homaliae ). Selaginella philipsonii is set aside further from S. homaliae by ovate or ovate-elliptic (vs. oblong) lateral leaves with the leaf apices obtuse to broadly acute or acute, tipped by (1) 2 (4), often divergent, long cilia (vs. truncate to obtuse, not tipped by cilia) and axillary and dorsal (vs. axillary) rhizophores.

Selaginella valdepilosa Baker is another South American moss-like species that could be confused with S. philipsonii ; however, the former has the lateral leaves broadly ovate-orbicular or broadly ovate-elliptic with the basiscopic bases distinctly, albeit sparsely, short- to long-ciliate and the median leaves broadly ovate-orbicular to ovate-deltate with both margins distinctly long-ciliate and the outer bases noticeably knobbed with the submarginal portion composed of round cells.

Selaginella philipsonii stands out from other moss-like taxa such as S. achotalensis Shelton & Caluff, S. apoda (L.) C. Morren, S. armata Baker, S. cristalensis Shelton & Caluff, S. eatonii Hieron. ex Small [syn.: S. armata var. eatonii (Hieron. ex Small) B.F. Hansen & Wunderlin, S. bracei Hieron. ex Small], S. ludoviciana A. Braun, S. orbicularifolia Shelton & Caluff, S. prasina Baker (syn.: S. undata Shelton & Caluff) and S. rotundifolia Spring by its main stems median leaves imbricate, oblong-elliptic and widely hyaline submarginal portion of the laminae, as well as lateral leaves long-ciliate along acroscopic margins. In keeping with Valdespino (1993) by following Buck (1978), Buck and Lucanski (1976) and Somers and Buck (1975) and contrary to Hansen and Wunderlin (2000), S. eatonii is considered a different species from S. armata as is S. ludoviciana from S. apoda . Finally, following Valdespino et al. (2015) S. undata is considered a synonym of S. prasina .

Figures

Figure 11. Selaginella philipsonii (Jermy & Rankin) Valdespino. A Section of upper surface of stem showing median and lateral leaves B Close-up of median leaf, upper surfaces; note, inner margin and submarginal portion of outer margin composed of elongate, idioblast-like and papillate cells and stomata (a) along outer margin C Close-up of median leaf distal portion, upper surface; note, apex tipped by long, divergent cilia, cells with papillae and stomata along outer margin D Close-up of median leaf, upper surface; note, marginal stomata (a), submarginal portion of outer margin composed of elongate, idioblast-like and papillate cells and lumen of lamina cells with multiple papillae E Section of lower surface of stem showing lateral leaves, outer halves of median leaves and rhizophore F Close-up of (E) G Close-up of lateral leaf, lower surface (one of the leaf shown in E) H Close-up of lateral leaf, lower surface (same leaf shown in G); note, stomata along midrib, elongate, idioblast-like and papillate cells and long cilia along acroscopic margin. A-H taken from Steyermark & Rabe 96652 (GH).