Selaginella crinita 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 : 68-69

Selaginella crinita Valdespino sp. nov. Figures 6 , 7

Diagnosis.

Selaginella crinita is morphologically similar to and may be confused with the Brazilian endemic, Selaginella jungermannioides (Gaudich.) Spring, but differs in its lateral leaves long-ciliate throughout the basiscopic margins (vs. along proximal ¼ and then serrulate distally), median leaves with margins long-ciliate throughout (vs. along proximal ¼, particularly on outer margins, otherwise short-ciliate to serrulate distally), and apices long-acuminate (vs. cuspidate to acuminate) with each acumen hyaline (vs. cusp or acumen green) tipped by 2-4 long cilia (vs. entire).

Type.

BRAZIL. Bahia: Mun. Água Quente, Pico das Almas, Vertente Oeste, trilho do povoado da Sta. Rosa, 35 km W of the city, 13°31'S, 42°00'W, 1100-1300 m, 1 Dec 1988, R. Harley & N. Taylor 27048 (holotype: NY!; isotypes: BM-n.v., CEPEC-n.v., K-n.v., PMA!, SPF-n.v.).

Description.

Plants terrestrial. Stems prostrate, stramineous, to 10 cm long, 0.3-0.5 mm diam., exarticulate, not flagelliform or stoloniferous, 1- or 2-branched. Rhizophores axillary, borne throughout stems, filiform, 0.1-0.2 mm diam. Leaves heteromorphic throughout, chartaceous, both surfaces glabrous, upper surfaces green or brownish (when old), lower surfaces silvery green or shiny brown (when old). Lateral leaves imbricate or distant, spreading to ascending, ovate-oblong, 1.5-2.0 × 0.5-1.0 mm; bases rounded, acroscopic bases strongly overlapping stems, basiscopic bases free from stems; acroscopic margins hyaline in a band 2-7 cells wide, the cells elongate and papillate parallel to margins, papillae in 1 or 2 rows over each cell lumen, long-ciliate along proximal ⅔ and short-ciliate along distal ⅓; basiscopic margins greenish to slightly hyaline in a band 1 or 2 cells wide, the cells as along acroscopic margins, long-ciliate throughout, apices obtuse to rounded, variously tipped by 1-5 cilia; upper surfaces comprising quadrangular to rounded, sinuate-walled cells, most of these covered by 15-30 papillae, without idioblasts or stomata, lower surfaces comprising elongate, sinuate-walled cells, most of these papillate and idioblast-like, papillae in 1 or 2 rows over each cell lumen, with stomata in 1 or 2 rows along midribs where cells are shortly elongate and sinuate. Median leaves imbricate, ascending, ovate-lanceolate to ovate-elliptic, 1.0-1.5 × 0.4-0.7 mm; bases rounded to truncate; margins hyaline in a band 2-5 cells wide, the cells elongate and papillate parallel to margins, papillae in 1 or 2 rows over each cell lumen, long-ciliate throughout; apices gradually tapering into a long-acumen, each acumen 0.12-0.15 mm, tipped by 2-5 cilia; both surfaces without idioblasts, upper surfaces comprising quadrangular to rounded, sinuate-walled cells covered by 15-30 papillae, with stomata along midribs, lower surfaces comprising elongate, sinuate-walled cells, without stomata. Axillary leaves ovate-oblong to oblong, otherwise similar to lateral leaves. Strobili terminal on branch tips, compact, quadrangular, 1.5-2.0 mm. Sporophylls monomorphic, without a laminar flap, ovate, 0.7-1.1 × 0.4-0.6 mm, each usually with a slightly developed and ciliate (cilia often caducous) keel along distal ½ of midribs; bases rounded; margins narrowly hyaline, long-ciliate; apices acute, tipped by 1 or 2 cilia; 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 to greenish, comprising elongate, sinuate-walled cells. Megasporangia in proximal portion in 2 ventral rows; megaspores white to creamy, rugulate-reticulate on proximal faces, reticulate-granular on distal faces, with granulate-echinulate and perforate microstructure on both faces, 250-258 μm diam. Microsporangia in 2 dorsal rows and, in distal portion, also in 2 ventral rows; microspores orange, rugulate-verrucate on proximal faces, broadly clavate or broadly baculate (if apices of projected, echinulate elements broken off) [Fig. 7F ] on distal faces, with echinulate microstructure on both faces, 25-33 µm.

Habitat and distribution.

Selaginella crinita is known only from the type collection from Pico das Almas, Serra do Rio de Contas, Bahia, Brazil, where it is probably a local endemic. It grows on shady rocky and sandy soil at 1100-1300 m.

Etymology.

The specific epithet is derived from the Latin crinitus, meaning long haired; this refers to the many, long cilia along leaf margins.

Conservation status.

There is insufficient data to definitively ascertain distributional range, abundance, and possible threats to this species. Nevertheless, since its type locality is in the Chapada Diamantina region of the Espinhaço Mountain Range, which is threatened by anthropomorphic activities ( Rapini et al. 2008), Selaginella crinita is tentatively considered vulnerable (VU), according to IUCN (2012) categories and criteria.

Discussion.

Selaginella crinita is a prostrate species that belongs to subg. Stachygynandrum and is characterized by its median leaves ovate-lanceolate to ovate-elliptic, with the inner and the outer margins symmetric, and apices tapering into a long-acumen with each acumen tipped by 2-5 cilia, lateral leaves ovate-elliptic to ovate-oblong, as well as long-ciliate leaf margins, and quadrangular to rounded sinuate-walled cells on upper surfaces of median and lateral leaves covered by many (15-30) papillae. Because of its imbricate and long-ciliate lateral leaves and leaves tipped by cilia, Selaginella crinita may be confused with Selaginella blepharodella . Selaginella crinita is easily separated from Selaginella blepharodella by its prostrate (vs. decumbent to suberect) habit, median leaves margins hyaline in a band 2-5 (vs. 5-15) cells wide, lateral leaves with obtuse to rounded (vs. acute) apices, and the cells of upper surfaces of median and lateral leaves covered by 15-30 (vs. 5-15) papillae.

Selaginella crinita belongs to a Neotropical group of Selaginella species, here informally termed the " Selaginella jungermannioides group", characterized mostly by creeping or prostrate habit, rhizophores usually distributed throughout the stems, median leaf apices acute, cuspidate, acuminate, or aristate, and lateral leaves often ovate-oblong or oblong with truncate, obtuse to broadly acute apices. The " Selaginella jungermannioides group" tentatively includes the South American taxa Selaginella applanata A. Braun (Colombia, Venezuela, and Peru), Selaginella homaliae A. Braun (Colombia and Brazil), Selaginella jungermannioides (Brazil), Selaginella schultesii Alston ex Crabbe & Jermy (Colombia), and Selaginella truncata H. Karst. ex A. Braun (Colombia, Peru, and Bolivia), as well as Selaginella lindenii Spring from southern Mexico. Among species in the " Selaginella jungermannioides group", Selaginella crinita is morphologically close to Selaginella applanata , Selaginella jungermannioides , and Selaginella lindenii . Selaginella crinita can be separated from Selaginella applanata by its median leaves with inner and outer margins symmetric (vs. inner margins straight and outer margins convex), long-acuminate (vs. long-aristate) apices tipped by cilia (vs. entire), and acroscopic margins of lateral leaves ciliate throughout (vs. along proximal ½). It can be easily distinguished from Selaginella lindenii by the upper surfaces of lateral and axillary leaves glabrous (vs. hispid), whereas from Selaginella jungermannioides it differs by the characters of marginal projections of leaves and form of the median leaf apices, as discussed in the diagnosis. Additionally, Selaginella crinita may be confused with Selaginella homaliae and Selaginella truncata , but it is set apart from them by its median leaf apices long-acuminate (vs. acute to short-cuspidate) and margins long-ciliate throughout (vs. dentate to serrate in Selaginella homaliae and in Selaginella truncata inner margins denticulate and outer margins sparingly long-ciliate along proximal ⅓, otherwise denticulate). Selaginella crinita also differs from the newly described Selaginella mucronata , which may be part of the " Selaginella jungermannioides group", by its median leaves ovate-lanceolate to ovate-elliptic (vs. orbiculate to broadly elliptic), with stomata on upper surfaces along midribs (vs. distributed throughout the leaf laminae), and apices long-acuminate (vs. mucronate or infrequently acute), as well as by having the cells on the upper surfaces of the lateral and median leaves covered by 15-30 (vs. 5-10) papillae.

Figures

Figure 6. Selaginella crinita Valdespino. A Section of upper surface of stem B Upper surface of median leaves C Section of lower surface of stem D Lower surface of lateral leaf A-D taken from holotype, Harley & Taylor 27048 (NY).

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).