Selaginella gioiae Valdespino, 2020

Valdespino, Ivan A., 2020, Taxonomic innovations in South American Selaginella (Selaginellaceae, Lycopodiophyta): description of five new species and an additional range extension, PhytoKeys 159, pp. 71-113 : 71

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

Diagnosis.

Selaginella gioiae differs from S. surucucusensis by the leaves on main stems before becoming fully heteromorphic, triangular-lanceolate, triangular-ovate or deltate (vs. ovate or broadly ovate), the leaves shortly before or after fourth to sixth or even further up along (vs. above first or second) stem branches fully heteromorphic and at this point onward lateral leaves oblong or oblong-ovate (vs. ovate or ovate-oblong), median leaf inner margins straight (vs. convex), and linear-lanceolate to lanceolate (vs. ovate to ovate-lanceolate) axillary leaves.

Type.

Colombia. Antioquia: Mpio. San Luis, 16 km SW de las partidas a San Luis, vía Medellín-Bogotá, Vereda La Josefina, 06°00'N, 74°50'W, 800 m, 25 Jun 1987 (fe), R. Callejas et al. 4180 (holotype: NY!; isotypes: HUA!, MO!, PMA!).

Description.

Plants terrestrial. Stems erect, stramineous, 0.6-1.2 m tall, (2.0)2.5-6.0 mm diam. on main stem before first branches, non-articulate, not flagelliform, stoloniferous, 2 or 3-branched, the terminal portion of the stem similar in shape to lateral branches (i.e., conform). Rhizophores axillary, ventral, dorsal, and seemingly lateral, borne on lower-most part of the stems and throughout stolons, stout, 0.3-2.0 mm diam. Leaves seemingly monomorphic and strongly appressed to the stem shortly before or after fourth to sixth or even further up along stem branches (depending on stem length), then heteromorphic (of three kinds of leaves: median, lateral, and axillar), coriaceous, upper surface dull to shiny green, striate or striate-corrugate, lower surface shiny yellowish green to silvery green, striate, those on main stem before fully heteromorphic triangular-lanceolate, triangular-ovate or deltate, the bases prominently raised and truncate with both edges rounded or slightly subcordate and glabrous, the margins narrowly hyaline and denticulate, the apices attenuate. Lateral leaves on main stems after leaves become fully heteromorphic, distant, ascending to spreading, oblong or oblong-ovate, 2.0-4.2(5.0) × 0.9-2.2(2.5) mm; bases truncate at central portion, glabrous, acroscopic bases strongly overlapping stems, rounded, entire, basiscopic bases free from stems, geniculate; margins on upper surfaces bordered by greenish, rectangular, and laevigate cells, acroscopic margins on lower surfaces narrowly bordered continuously by a hyaline band comprised of idioblasts, the band 1-3 cells wide, the idioblasts elongate, straight-walled, and papillate, the papillae in a single row over each cell lumen, basiscopic margins on lower surfaces bordered continuously by greenish, elongate, straight-walled, laevigate cells, acroscopic margins entire to sparingly denticulate along proximal ⅔, otherwise denticulate distally, basiscopic margins entire or scarcely denticulate; apices obtuse, entire or obscurely denticulate; upper surfaces consisting of irregularly shaped, somewhat rectangular, straight to sinuate-walled cells (often difficult to distinguish because of waxy deposits), with some of these sparse- and obscurely papillate, papillae in one row on each cell lumen, without stomata or with few, obscure submarginal stomata, sparsely distributed along basiscopic margins, lower surfaces consisting of elongate, sinuate-walled cells and of elongate, straight-walled, papillate idioblasts, papillae 6-22 in one rows on each cell lumen, with stomata on 3-7 rows along central most portion of midribs. Median leaves on main stem after leaves fully heteromorphic, distant to slightly imbricate, ascending, ovate to ovate-lanceolate, 1.4-3.4 × 0.8-1.7 mm; bases glabrous, truncate to truncate-oblique, without auricles or the outer bases with a rounded nob; margins bordered continuously by a narrow hyaline band comprised of idioblasts, the band 1-3 cells wide, the idioblasts similar to those in acroscopic, hyaline marginal bands of lateral leaves, lower surfaces, the inner margins, straight, entire throughout or entire along proximal ½ and sparsely denticulate on distal ½, the outer margins convex, denticulate throughout; apices acute or attenuate, each 0.1-0.5 mm long, entire at tip or tipped by 1-3 small teeth; upper surfaces similar to those on upper surfaces of lateral leaves but more abundantly covered by irregularly arranged, papillate idioblasts, the papillae 3-14 in one row on each cell lumen, with stomata in 3-7 rows along midribs and few submarginal, along basiscopic ⅓ of outer margins, lower surfaces comprising elongate (somewhat jigsaw puzzle-like), sinuate-walled cells, without idioblasts and stomata. Axillary leaves on main stem after leaves fully heteromorphic linear-lanceolate to lanceolate, 2.5-4.5 × 1.0-1.7 mm; bases truncate, prominently raised, glabrous; margins as in lateral leaves, denticulate throughout; apices gradually tapering, broadly acute, tipped by 1-3 teeth; both surfaces as in lateral leaves. Strobili terminal on main stem and each branch tips, quadrangular, 0.5-5 cm long. Sporophylls monomorphic, without a laminar flap, each with a well-developed and glabrous keel along midribs, ovate-lanceolate, 1.5-2.0 × 0.6-1.0 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, denticulate throughout; apices attenuate to acuminate, the acumen 0.1-0.3 mm, tipped by 1-3 small teeth; dorsal sporophylls with upper and lower surfaces as in vegetative leaves; ventral sporophylls with both surfaces, silvery green to hyaline, comprised of elongate, papillate, sinuate-walled cells and of papillate idioblasts. Megasporangia intermixed with microsporangia along two ventral rows; megaspores white to beige colored, 325-350 µm diam., proximal faces rugulate with a strongly developed equatorial flange, the microstructure echinate to slightly granular, distal faces reticulate, the reticulae open (incomplete) to closed and the microstructure echinate and perforate. Microsporangia in two dorsal rows and intermixed with megasporangia along two ventral rows; microspores light orange, 18-20 µm diam., proximal faces rugulate-echinate on proximal faces with slightly punctate or rugulate microstructure, distal faces capitate or baculate, with each caput or bacula and the microstructure echinate or rugulate.

Habitat and distribution.

Selaginella gioiae grows on lowland and montane rainforests at 80-1480 m. It is known from tropical rainforest ecosystems on both sides of northwestern Andes and in the Amazon basin, specifically in western Colombia and central-eastern Ecuador and northwestern Peru. It has been collected in fertile condition from February to December.

Eponomy.

This unique, tall Selaginella species is named after Christopher Gioia (1968-), who as my longtime companion has steadfastly encouraged my work on the genus.

Conservation status.

Selaginella gioiae is a widely distributed species that grows at low and high elevations with collections continuously made from the late nineteenth- to early in the twenty-first century over a relatively wide range in South America, which suggest it is comprised of healthy populations. Accordingly, it is here considered of Least Concern (LC) based on IUCN (2012).

Additional specimens examined (paratypes).

Colombia. Antioquia: Mpio. San Luis, Autopista Medellín-Bogotá, Vereda La Josefina, road to Tulipán, caño La Mariola, 800 m, 18-19 Feb 1984, Hoyos & Hernández 925 (MO); Río Guatapé, 3800 ft [ca. 1158 m], 23 Feb 1880, Kalbreyer 1434 (B-4 sheets). Chocó: Mpio. Quibdó, Corr. Guayabal, Río Hugón, 14 Oct 1985, García et al. 55 (COL). Nariño: Barbacoas, s.d., Triana s.n. (B), along road between Junín and Barbacoas, 1.9 km NE of Junín, 01°21'S, 78°06'W, 1300 m, 27 Feb 1992, Croat 72431 (MO). Valle de Cauca: Costa del Pacífico, Río Raposo, 20-50 m, 26 Mar 1963, Idrobo 5255 (COL); Cordoba, Dagua Valley, 80-100 m, 6-8 May 1922, Killip 5092 (GH). Ecuador. Morona-Santiago: road between Gualaquiza and Indanza, 12 km S of Indanza along river, 03°11'47"S, 78°33'06"W, 1250 m, 8 Sep 2002, Croat 87275 (MO-2 sheets); Ridge between ríos Ontza and Chupiasa, 02°40"S, 78°W, 4300-4700 ft [1311-1433 m], 17 Nov-5 Dec 1944, Camp E-1194 (NY). Napo: El Chaco, Río Granadillo, Campamento de INECEL, Codo Alto, 00°08'S, 77°28'W, 1300 m, 13-15 Sep 1990, Palacios 5783 (MO, UC); Reserva Biológica Jatun Sacha, Río Napo, 8 km abajo de Misahuallí, 01°04'S, 77°36'W, 450 m, 17 Jan-6 Feb 1987, Cerón 748 (AAU, MO, UC). Napo-Pastaza: Mera, near Mangayacu, [ca. 01°42'27"S, 78°52'23"W], ca. 1100 m, Asplund 19100 (S). Pastaza: El Porvenir, ca. 5 km N of Puyopungo, 17 Nov 1976, Lugo 4897B (BM); Mera, 1100 m, 25 May-6 Jun 1968, Harling et al. 9779 (BM), 10128 (BM), between Puyo and Baños, ca. 5 km W of Mera, 01°26'S, 78°08'W, 1100 m, 7 Mar 1992, Croat 72833 (MO); Near Napo road, 9 km N of Puyo, 18 Apr 1958, Prescott 1361 (NY); Hacienda San Antonio de Barón von Humboldt, 2 km NE de Mera, 01°27'S, 78°06'W, 1100 m, 20 Feb-20 Mar 1985, Palacios et al. 23A (AAU, MO, NY), Zaruma et al. 6 (AAU, MO, NY, UC); Vicinity of Shell, 1.6 km N of main Baños-Puyo road, along Río Claro, 40°29'39"S, 78°03'52"W, 1085 m, 9 Oct 2007, Croat et al. 99520 (MO). Tungurahua: ca. 5 km E of town of Río Negro, 1350 m, 17 Jan 1973, Humbles 6120 (MO). Zamora-Chinchipe: Cordillera del Condor, Chinapintza, trail to Destacamento Mayaycu Alto, 04°03'S, 78°35'W, 1350-1480 m, 6 Dec 1990, Øllgaard 98418 (AAU); Vicinity of mining camp at Río Tundaime, along Río Quimi, 03°31'10"S, 78°25'53"W, 900-1000 m, 3 Nov 2004, van der Werff et al. 19255 (MO, NY). Peru. Amazonas: Dist. El Cenepa, Tutino, Quebrada Tutino, 04°34'31"S, 78°11'34"W, 300 m, 22 Jul 1997, Rojas et al. 136 (MO, NY).

Discussion.

Selaginella gioiae is characterized by its fern-like habit, erect stems, each 0.6-1.2 m tall, leaves on main stem normally fully heteromorphic shortly before or after fourth to sixth or even further shortly before or after fourth to sixth or at higher up branches depending on main stem length, with margins bordered by a narrow band of hyaline, papillate, idioblasts. On main stems it has oblong or oblong-ovate lateral leaves, median leaf bases glabrous, truncate to truncate-oblique, without auricles or the outer bases rounded or with a rounded nob, linear-lanceolate or narrowly lanceolate axillary leaves, megaspores with a prominent equatorial flange, and microspores distal faces capitate or baculate, each caput or baculum usually micro-echinate. Selaginella gioiae is further notable by its median leaf lower surfaces with frequently very well defined or marked midribs and strobili tips occasionally displaying vegetative growth.

Selaginella gioiae is one of the tallest species within the " Selaginella flabellata group" and among these taxa it may be confused with S. surucucusensis because of their fairly similar median leaves with inconspicuous, short-elongate or punctate idioblasts on the upper surfaces. Selaginella gioiae , however, is set aside from S. surucucusensis by the characters listed in the diagnosis and by its median leaf with the outer bases rounded or with a rounded nob (vs. with a distinct auricle) and acute, attenuate or short-acuminate (vs. attenuate or acuminate to short-aristate) apices, each less than ¼ (vs. ¼) the length of the lamina. Selaginella cuneata Mickel & Beitel is another member of the " Selaginella flabellata group" with inconspicuous short-elongate or punctate idioblasts on the upper surface of median leaves. Selaginella gioiae differs from the latter by its median leaf outer half of the lamina at least ¼ to ½ wider (vs. twice as narrow) as the inner half, and hyaline (vs. greenish) bordered margins of median leaves and on acroscopic margins of lateral leaves.

Figures

Figure 1. Selaginella gioiae Valdespino. A Habit, upper surface of stem and (a) detail of terminal strobili on branch, lower surface B branch section, upper surface C branch section showing terminal strobilus, lower surface D median leaves with details of a leaf margin, upper surface E, F branch section showing axillary leaf (E) and lateral leaf (F), lower surface. A-F line drawing made from the holotype. Illustration by Haruto Fukuda.

Figure 2. Selaginella gioiae Valdespino. A Lateral leaf from stem branch, upper surface B proximal half of lateral leaf, upper surface (same leaf shown in A) C distal half of lateral leaf, upper surface (same leaf shown in A) D lateral leaf, lower surface E proximal half of lateral leaf, lower surface (same leaf shown in D) F distal half of lateral leaf, lower surface (same leaf shown in D); note, elongate and papillate idioblasts (a) and stomata along midrib (b) G median leaf from stem branch, upper surface H proximal half of lateral leaf, upper surface (same leaf shown in G) I distal half of median leaf, upper surface (same leaf shown in G); note, elongate and papillate idioblasts (a) and stomata along midrib (b) J median leaf from stem branch, lower surface K proximal half of median leaf, lower surface (same leaf shown in J) L distal half of median leaf, lower surface (same leaf shown in J). A-L taken from the holotype.

Figure 3. Selaginella gioiae Valdespino. A Axillary leaf from stem branch, upper surface B proximal half of axillary leaf, upper surface (same leaf shown in A) C distal half of axillary leaf, upper surface (same leaf shown in A) D axillary leaf from stem branch, lower surface E proximal half of axillary leaf, lower surface (same leaf shown in D) F distal half of axillary leaf, lower surface (same leaf shown in D); note, elongate and papillate idioblasts (a) and stomata along midrib (b). A-F taken from the holotype.

Figure 4. Selaginella gioiae Valdespino. A Megaspore, proximal face B detail of megaspore, proximal face C megaspore, distal face, equatorial view D detail of megaspore, distal face E microspore, proximal face F detail of microspore, proximal face. A-F taken from the holotype.

Figure 5. Distribution of Selaginella gioiae □, S. surucucusensis ▲, S. xanthoneura ●.