Pleopeltis mexicana (Fée) Mickel & Beitel
Descripción
Rhizomes creeping, 1.5–2 mm diam.; rhizome scales dimorphic, 0.8–1 mm long along rhizomes, ovate-lanceolate, densely comose, centers black, margins narrow, pale, denticulate, 1.5–2.5 mm long at stipe bases, narrowly lanceolate, centers black to rarely concolorous, margins narrow, pale, denticulate; fronds dimorphic, sterile ones 2–3 times the width and 1⁄2–3⁄4 the length of the fertile, distant; stipes 1⁄4–1⁄3 the frond length, terete, 1–8 cm long; blades coriaceous, dimorphic, simple, the sterile ones lanceolate, 10–20(–25) X 2.2–3.2(–4) cm, the fertile ones lanceolate to linear-lanceolate, (12–)15–25(–30) X 0.8–2(–2.5) cm; midribs abaxially black nearly to blade apices; veins not readily visible; abaxial blade scales sparse, round, 0.3–0.5 mm diam., brown-centered with margins pale brown to white, fimbriate; sori oblong, soral scales peltate, 0.3–0.5 mm diam., similar to laminar scales; 2n=68 (Oax; Andrews, 1994).A
Forma de vida
o epipétrica. EpífitaA
Ejemplar revisado
Chis (Croat 40678, UC). Col (Goldsmith 42, UC). DF (Lyonnet 1913, MEXU, US). Dgo (Sánchez 727, MEXU). Gro (Lorea 855, ENCB). Hgo (Moore 1972, UC). Jal (Breedlove 39285, CAS). Méx (Rzedowski 22828, DS, ENCB). Mich (Breedlove 64340, CAS). Mor (Hitchcock & Stanford 7101, DS, UC). Nay (Breedlove 45516, CAS). NL (Reeves 6035, 6116, ASU). Oax (Wendt et al. 4987, CAS, CHAPA, MEXU). Pue (Orcutt 3993, DS). Qro (Breedlove 66652, CAS). SLP (Lynch 9031, TEX, det. uncertain). Sin (Gentry 5882, 6334, ARIZ, DS). Ver (Valdivia Q. 2216, UC, XAL).A
Elevación
1300 – 2900 mA
Tipo de vegetación
Bosque de neblina/mesófiloA
Categoría IUCN
No incluidaB
Categoría NOM-059-SEMARNAT-2010
No incluidaC
Discusión taxonómica
Pleopeltis mexicana is closely allied to P. macrocarpa (which is unknown from Mexico but occurs in Central America, South America, the Antilles, and Africa) and has usually been treated as a variety of it. The former is distinct in its brown-centered soral scales and lanceolate, somewhat dimorphic blades. Some specimens from Guerrero, e.g., Rzedowski & McVaugh 108 (ENCB), Martínez S. 886 (IEB), and Lorea 1635 (IEB), have many of the abaxial laminar scales with a short tail, thus tending towards P. conzattii, which is also closely related. Pleopeltis mexicana is best distinguished from P. polylepis by the conspicuously comose rhizome scales, dimorphic blades, and dimorphic rhizome scales, those at the base of the blades being tan, more lanceolate, and not comose.
Pleopeltis mexicana appears to hybridize with Polypodium thyssanolepis, forming X Pleopodium tricholepis Mickel & Beitel (Figs. 235A–C; Amer. Fern J. 76: 17. 1987. Type. Mexico. Oaxaca: Distrito Etla–Cuicatlán, 39 km N of Rte. 190 past Telixtlahuaca, 1900 m, Mickel 3873, NY!; isotype UC!). This hybrid between a simple-bladed species and a pinnatifid species is intermediate morphologically between the suspected parents, most obviously in blade shape: irregularly pinnatisect, 16–18 X 5–6 cm, broadest proximally; lobes 4–6 pairs, 5–7 mm wide. Blade scales are also intermediate between the putative parents: adaxial surfaces with scattered to dense, deeply fimbriate scales, mostly lanceolate (1–1.5 mm long), some round (0.8–1 mm wide), with brown centers grading to whitish margins, midribs dark with lanceolate scales, 1.5–2 mm long, adaxial surfaces with sparse, deeply lacerate, lanceolate scales. The spores are malformed. The hybrid is known only from the type gathering and was collected with Polypodium thyssanolepis (see UC isotype). Although P. conzattii was the only simple-bladed species of Pleopeltis found at the same locality, the presence of round scales and the absence of blackcentered rachis scales makes that species unlikely as a posible parent. The laminar scales are deeply bicolorous as one would expect in hybrids involving P. mexicana. Pleopeltis astrolepis and P. crassinervata are generally species of lower elevations, while P. polylepis is usually found at higher elevations.
The existence of this hybrid shows the very close relationship between Pleopeltis (mexicana) and Polypodium (thyssanolepis) and the inappropriateness of separating the two genera on the basis of blade dissection. A very similar hybrid in the Greater Antilles and South America (Jamaica, Hispaniola, Venezuela, Ecuador, Peru) is Pleopeltis X leucospora (Klotzsch) Moore, which is Pleopeltis macrocarpa (Bory ex Willd.) Kaulf. X Polypodium thyssanolepis.A
Pleopeltis mexicana appears to hybridize with Polypodium thyssanolepis, forming X Pleopodium tricholepis Mickel & Beitel (Figs. 235A–C; Amer. Fern J. 76: 17. 1987. Type. Mexico. Oaxaca: Distrito Etla–Cuicatlán, 39 km N of Rte. 190 past Telixtlahuaca, 1900 m, Mickel 3873, NY!; isotype UC!). This hybrid between a simple-bladed species and a pinnatifid species is intermediate morphologically between the suspected parents, most obviously in blade shape: irregularly pinnatisect, 16–18 X 5–6 cm, broadest proximally; lobes 4–6 pairs, 5–7 mm wide. Blade scales are also intermediate between the putative parents: adaxial surfaces with scattered to dense, deeply fimbriate scales, mostly lanceolate (1–1.5 mm long), some round (0.8–1 mm wide), with brown centers grading to whitish margins, midribs dark with lanceolate scales, 1.5–2 mm long, adaxial surfaces with sparse, deeply lacerate, lanceolate scales. The spores are malformed. The hybrid is known only from the type gathering and was collected with Polypodium thyssanolepis (see UC isotype). Although P. conzattii was the only simple-bladed species of Pleopeltis found at the same locality, the presence of round scales and the absence of blackcentered rachis scales makes that species unlikely as a posible parent. The laminar scales are deeply bicolorous as one would expect in hybrids involving P. mexicana. Pleopeltis astrolepis and P. crassinervata are generally species of lower elevations, while P. polylepis is usually found at higher elevations.
The existence of this hybrid shows the very close relationship between Pleopeltis (mexicana) and Polypodium (thyssanolepis) and the inappropriateness of separating the two genera on the basis of blade dissection. A very similar hybrid in the Greater Antilles and South America (Jamaica, Hispaniola, Venezuela, Ecuador, Peru) is Pleopeltis X leucospora (Klotzsch) Moore, which is Pleopeltis macrocarpa (Bory ex Willd.) Kaulf. X Polypodium thyssanolepis.A