Selaginella altheae Valdespino, 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 : 14-17

Selaginella altheae Valdespino sp. nov. Figures 1 , 2 , 3 , 4 , 5

Diagnosis.

Selaginella altheae differs from S. lechleri Hieron. by the main stem leaves becoming obviously dimorphic above or 1-4 cm (vs. 3-6 cm) below the first branches of the stems, its lateral leaves bases oblique with a seemingly inner [actually it is an acroscopic] (vs. lacking) auricle that is tufted with 3-15 hairs (vs. bases glabrous) and the axillary leaves rounded to cordate or truncate with two, distinct, incurved and ciliate (vs. lacking) auricles at least up to the third or fourth branches along the stems.

Type.

BRAZIL. Amazonas: Río Negro, Río Cuaburí, along Rio Tucano , vicinity of Base Camp , 20 Nov 1965, B. Maguire, J.A. Steyermark & C.K. Maguire 60249 (holotype: NY) .

Description.

Plants terrestrial. Stems erect, stramineous, (20)30-65 cm long, 1.4-3.0 mm diam., non-articulate, usually not flagelliform, stoloniferous, 2-4-branched. Rhizophores axillary, ventral and dorsal, borne on lower-most part of the stems and throughout stolons, filiform or stout, 0.2-1.0 mm diam. Leaves seemingly monomorphic and strongly appressed to the stem shortly before or after first branches, then dimorphic throughout, coriaceous, upper surfaces dull to shiny green, slightly corrugate, lower surfaces shiny yellowish green to silvery green, striate, the outer bases short- to long-auricled (these tend to disappear on leaves above first branches), the auricle short- to long-ciliate, cilia 2-10, each 0.2-0.5 mm long. Lateral leaves on main stem after first branches distant to slightly imbricate, strongly ascending to slightly spreading, ovate-deltate to ovate-oblong, 2.0-4.2 × 0.9-2.2 mm; bases truncate, on main stem before first branches with an inner, acroscopic bases strongly overlapping stems, rounded, entire, basiscopic bases free from stems, geniculate, usually ciliate, cilia 1-5, each 0.1 to 0.2 mm long; acroscopic margins on main stem leaves after second branches greenish to narrowly hyaline along proximal ⅔, 1-3 cells wide with the cells elongate, sinuate-walled and glabrous, parallel to margins, otherwise greenish, on branch leaves narrowly hyaline along proximal ¾ and cells as those on main stem, otherwise greenish distally, long-ciliate along proximal ½-¾, otherwise becoming short-ciliate to dentate distally, basiscopic margins greenish, comprising similar cells as in acroscopic margins, entire along proximal ⅔, otherwise sparsely denticulate distally; apices gradually tapering, acute to broadly acute, tipped by 1-3 teeth; upper surfaces comprising irregularly shaped, somewhat rectangular to quadrangular, sinuate-walled cells (often difficult to distinguish because of waxy deposits), with some obscure, idioblast-like, short quadrangular to round or elongate and variously papillate cells, without stomata or with some obscure along basiscopic margins, lower surfaces comprising elongate, sinuate-walled cells, with many of these idioblast-like, elongate and papillate, papillae 5-14 in 1 or 2 rows on each cell lumen, stomata on 1-5 rows along midribs. Median leaves on main stems after first branches distant to slightly imbricate, ascending, ovate, broadly ovate to ovate-elliptic, 1.4-3.0 × 0.8-1.7 mm; bases truncate to truncate-oblique, the outer base tufted with (4)6-20 long hairs, without auricles; margins greenish to narrowly hyaline, 1 or 2 cells wide with the cells elongate, slightly sinuate-walled and mostly glabrous or papillate, parallel to margins, the inner margins short-ciliate along proximal ⅔, denticulate along distal ⅓, the outer margins entire along proximal ⅓, becoming short-ciliate along medial ⅓, otherwise denticulate on distal ⅓; apices acute to slightly acuminate, the acumen ca. 0.1 mm, tipped by 1-3 teeth; upper surfaces comprising irregular (jigsaw puzzle-like), sinuate-walled cells (often difficult to distinguish because of waxy deposits), some of these papillate, papillae 3-14, irregularly arranged, without elongate idioblasts, stomata in 3-7 rows along the midribs and marginal to submarginal along basiscopic ⅓ of outer margins, lower surfaces comprising elongate (jigsaw puzzle-like), sinuate-walled cells, without elongate idioblasts and stomata. Axillary leaves on main stem after first branches ovate-lanceolate, 2.0-3.0 × 0.9-1.5 mm; bases rounded to cordate or truncate, with two small, long-ciliate auricles up to, at least, the fifth branch and then becoming small lobes; margins narrowly hyaline as in median leaves, long-ciliate along proximal ⅘, otherwise short-ciliate to denticulate distally; apices gradually tapering, acute, tipped by 1-3 teeth; both surfaces as lateral leaves. Strobili terminal on main stem and each branch tip, quadrangular, 0.3-1.7 cm. Sporophylls monomorphic, without a laminar flap, each with a slightly developed and seemingly glabrous keel along midribs, ovate to ovate-lanceolate, 0.8-1.0 × 0.4-0.6 mm; bases rounded to truncate; margins narrowly hyaline, 1 or 2 cells wide with the cells elongate, slightly sinuate-walled and glabrous, parallel to margins, short-ciliate along proximal ½, otherwise denticulate to entire distally; apices acute to acuminate, the acumen 0.1 to 0.2 mm, tipped by 3 tooth-like projections; dorsal sporophylls with upper and lower surfaces as in vegetative leaves; ventral sporophylls with both surfaces, silvery green to hyaline, comprising elongate, papillate, sinuate-walled cells. Megasporangia in 2 ventral rows; megaspores white, rugulate-reticulate on proximal faces with a slightly developed equatorial flange and microstructure granulate, perforate and sparsely echinate, mostly open to somewhat closely reticulate on distal faces with the microstructure sparse and minutely echinate and perforate, 180-250 µm diam. Microsporangia in 2 dorsal rows; microspores orange, echinate-rugulate on proximal faces with punctate microstructure, capitate or baculate on distal faces with each caput or bacula and the rest of the surface with echinate microstructure, 20-30 µm diam.

Habitat, distribution and phenology.

Selaginella altheae grows on lowland and montane rainforests at 140-450 m; it is known from the Amazon basin of Colombia, Venezuela and Brazil and found fertile from April through to November.

Eponomy.

I am delighted to dedicate this graceful, fern-like species with shiny idioblasts on leaf surfaces to my mother, Althea Quintero (1939-), whose gentle, selfless demeanor, as well as strength and enlightening life-long support has guided and buttressed my life and professional career. She has adorned my path in life in the same manner as her lovely and resilient namesake flower does in nature.

Conservation status.

This is a widely distributed species that grows at low elevations in Tropical rainforests of the Amazon basin; therefore, it is considered here of Least Concern (LC), according to IUCN (2012) categories and criteria.

Additional specimens examined (paratypes).

COLOMBIA. Amazonas: Río Amazonas, along a road 8-14 km N of Leticia, 450 m, 3-5 Jul 1974, Breedlove 36331 (CAS) . VENEZUELA. Amazonas: Rivers Casiquiare, Vasiva [Pasiba] and Pasimoni , 1853-54, Spruce 3380 (GH, OXF, W); Depto. Rio Negro , along river that flows out of the Canyon Grande of Cerro de la Neblina , 2-4 km upriver from base, 10 Feb 1984, Funk & Liesner 6148 (NY, RB [digital image], US), trail leading N-NE, 28 Feb 1984, Funk 6419 (MO, NY, US), Rio Mawarinuma , 00°50'N, 66°10'W, 140 m, 27 Nov 1984, Anderson 13372 (CAS, F, UC), Cerro de la Neblina Base Camp on Rio Bario ( Rio Mawarinuma ), SE of camp, 00°49'50"N, 66°09'40"W, 140 m, 26 Jan 1985, Beitel & Buck 85042 (NY), 27 Jan 1985, Beitel & Buck 85064 (MO, NY, UC), Beitel & Buck 85068 (NY), 17 Feb 1985, Beitel & Buck 85210 (NY-2 sheets), 4 Dec 1984, Bell 406 (UC), 2-3 Jul 1984, 00°50'N, 66°10'W, 25 Nov 1984, Croat 59312 (MO, NY), 2-3 Jul 1984, Davidse & Miller 26886 (UC), 4-5 Jul 1984, Davidse & Miller 26972 (MO, UC), ca. 160 m, 27 Nov 1984, Kral & Liesner 71851 (UC), ca. 180 m, 4 Dec 1984, Kral 71997 (UC), 0 to 2 km W of Cerro de La Neblina Base Camp, which is on Rio Mawarinuma , 140 m, 00°50'N, 66°10'W, 7 Feb 1984, Liesner 15716 (MO), Rio Mawarinuma , below Cerro Neblina Camp, 00°50'N, 66°11'W, 140 m, 16 Apr 1984, Gentry & Stein 46677 (MO), ca. 2 km S of Base Camp [Cerro Neblina base camp], along Marawanumi River , 00°50'N, 66°10'W, 140 m, 11 Apr 1984, Thomas & Plowman 3014 (NY), along Rio Marawinuma , SE of Base Camp [Cerro Neblina base camp], 00°50'N, 66°09'W, 140 m, 30 Apr 1984, Thomas & Samuels 3291 (NY, PMA) .

Discussion.

Selaginella altheae is characterized by its erect, fern-like habit, axillary, lateral and dorsal rhizophores, leaves on main stems becoming obviously dimorphic above or 1-4 cm below the first branches and, below this point, the lateral leaf bases oblique with an acroscopic auricle that is tufted with 3-15 stiff hairs and median leaves above first branches in main stems with oblique, not auricled bases, with the outer bases slightly prominent and tufted with (4)6-20stiff hairs.

Selaginella altheae , S. lechleri and other members of the S. flabellata group, have microspores distal faces with echinate microstructure. Likewise, S. altheae and S. oaxacana Spring have dorsal rhizophores, as do other members of the S. flabellata group. These two characters, therefore, might represent synapomorphies that define the S. flabellata group. Nevertheless, dorsal rhizophores, which are typical of articulate Selaginella species, are also found in other taxa such as S. psittacorhyncha ( Valdespino 2017) and S. philipsonii , suggesting that this character is under-reported and, perhaps, of a wider presence in the genus than hitherto acknowledged. Similarly, different degrees of spore echinate microstructure could occur in other unrelated taxa. Therefore, the occurrence of these characters in morphologically unrelated species warrants further morphological, anatomical and molecular studies throughout the genus to ascertain their evolutionary and phylogenetic implications. Interestingly, a specimen of S. altheae (i.e. Thomas & Samuels 3291, NY) has flagelliform tertiary branch apices that develop strobilus at their tips.

Selaginella altheae is morphologically close to S. flabellata and S. lechleri . Their leaves on the main stems below the first branches are seemingly monomorphic and have similar median leaf above the first branches with the outer bases slightly prominent and tufted with either few or many short- to long cilia, as well as submarginal to marginal stomata along the proximal ⅓ on each outer half of the laminae. Nevertheless, S. altheae is set aside from S. flabellata by its median leaves on main stems ovate, broadly ovate to ovate-elliptic (vs. broadly ovate to ovate-oblong) with the inner and outer halves on the main stems equal in width or the inner halves slightly wider than the outer halves (vs. usually the outer halves distinctly wider) and lateral leaves acroscopic margins long-ciliate along proximal ½-¾ (vs. ¼-½), otherwise distally short-ciliate to dentate (vs. entire or denticulate). It differs further from S. flabellata by its megaspores proximal faces rugulate-reticulate (vs. rugulate) with granulate, perforate and sparsely echinate and perforate (vs. tuberculate, mostly psilate to minutely echinate and perforate) microstructures and distal faces mostly open or somewhat closely reticulate (vs. mostly closely reticulate) with minutely echinate and perforate (vs. prominently tuberculate, psilate and perforate) microstructures. Selaginella altheae differs from S. lechleri , with which it has been confused in the past, by the characters discussed under the diagnosis and by the megaspores proximal faces rugulate-reticulate (vs. reticulate) with granulate, perforate and sparsely echinate (vs. with strongly echinate and perforate) microstructures, while the distal faces are mostly open or somewhat closely reticulate (vs. mostly closely reticulate) with sparse and minutely echinate and perforate (vs. abundantly echinate and perforate) microstructures.

Selaginella altheae may also be confused with the Central and South American S. anceps (C. Presl) C. Presl because of their auriculate leaf bases (i.e. auriculae present on lateral leaves of S. altheae and on seemingly monomorphic leaves of S. anceps ) on main stems below the first branches. Selaginella altheae is set aside from the latter by its obviously dimorphic leaves immediately above or 1-4 cm below the first (vs. above fourth) branches of the main stems and median leaf bases on main stems above the first branches without auricles (vs. with inner and outer ciliate auricles or only with an outer ciliate auricle). It is further distinguished from S. anceps by its megaspores proximal faces with a slightly developed (vs. lacking) equatorial flange, rugulate-reticulate (vs. reticulate) ornamentation with granulate, perforate and sparsely echinate (vs. with perforate and strongly echinate) microstructures, while the distal faces ornamentation is mostly open or somewhat (vs. mostly) closely reticulate with sparse and minutely echinate and perforate (vs. shortly echinate, granulose and perforate) microstructures.

Figures

Figure 1. Selaginella altheae Valdespino. A Habit, upper surface of stem B Close up of section of the upper surface of the stem C Habit, lower surface of stem D Close up of section of the lower surface of the stem. A-D digitized images of holotype, Maguire et al. 60249 (NY).

Figure 2. Selaginella altheae Valdespino. A Habit B Section of main stem above first branch showing median leaves, upper surface C Section of main stem above first branch showing lateral leaves and axillary leaf, lower surface D Close-up of strobilus. A-D line drawings of holotype, Maguire et al. 60249 (NY). Illustration made by Ruben Lozano.

Figure 3. Selaginella altheae Valdespino. A Section of upper surface of stem branch B Close-up of lateral leaf from stem branch, upper surface C Section of lower surface of stem branch D Close-up of lateral leaf (from branch), lower surface E Close-up of distal portion and apex of lateral leaf, lower surface (same leaf shown in B); note, elongate and papillate idioblasts (a) and stomata along midrib (b) F Close-up of proximal (basal) portion of lateral leaf, lower surface (same leaf shown in B); note, elongate and papillate idioblasts (a) and stomata along midrib (b). A-F taken from holotype, Maguire et al. 60249 (NY).

Figure 4. Selaginella altheae Valdespino. A Section of upper surface of stem branch showing median and lateral leaves B Close-up of median leaves from stem branch, upper surfaces C Close-up of median leaf from stem branch, lower surface D Close-up of median leaf from stem branch, upper surface E Close-up of distal portion and apex of median leaf, upper surface (same leaf shown in D); note, punctate to shortly elongate and papillate idioblasts (a) and stomata (b) along midrib F Close-up of proximal portion and base of median leaf, lower surface (same leaf shown in D); note, punctate to shortly elongate and papillate idioblasts (a), stomata (b) along midrib and submarginal and marginal portion near outer base and long cilia (c) on outer base. A-F taken from holotype, Maguire et al. 60249 (NY).

Figure 5. Selaginella altheae Valdespino. A Megaspore, proximal face B Close-up of megaspore, proximal face C Megaspore, distal face D Close-up of megaspore, distal face E Microspore, proximal face F Microspore, distal-equatorial-proximal faces G Close-up of microspore, distal-equatorial faces; note, capitate projections and echinulate microstructure. A-G taken from holotype, Maguire et al. 60249 (NY).