Astrolepis obscura J.B.Beck & Windham
Descripción
Astrolepis integerrimae persimilis sed pagina adaxiale pinnarum squamis persistentibus obtecta, squamis paginae adaxialis 18–36 (haud 10–15) ciliis praeditis, sporangiis 64 (haud 32) sporas parvas (45–49, haud 59–70 mu diametro) continentibus recedit.
Rhizomes, erect, compact; rhizome scales uniformly brown, 5–10 × 0.12–0.25 mm, margins denticulate; leaves 14–22 cm; blades linear, 5–15 cm, 1-pinnate; rachis scales dimorphic, the larger ones lanceolate, the main body 1.5–2.4 mm × 250–370 μm, the margins ciliate; pinnae 30–60, mostly alternate, the largest 7–14 × 2–5 mm wide, oblong-linear to elliptic with narrowly to broadly rounded apices, entire or slightly asymmetrically lobed, lobes 2–5; abaxial surfaces concealed by a dense covering of scales, these scales lanceolate, the main body 1.4–2.7 mm × 240–500 μm, the margins long-ciliate proximally and ciliolate distally; adaxial surfaces concealed by a dense covering of persistent scales, providing a silvery appearance; adaxial scales with a lanceolate main body 0.7–2.6 mm × 80–180 μm, long-ciliate, longest cilia 200–550 μm long, typically less than one half the length of the main body, 18–36 cilia per scale; sporangia containing 64 spores averaging spore ca. 45–49 μm in diam.
A
Rhizomes, erect, compact; rhizome scales uniformly brown, 5–10 × 0.12–0.25 mm, margins denticulate; leaves 14–22 cm; blades linear, 5–15 cm, 1-pinnate; rachis scales dimorphic, the larger ones lanceolate, the main body 1.5–2.4 mm × 250–370 μm, the margins ciliate; pinnae 30–60, mostly alternate, the largest 7–14 × 2–5 mm wide, oblong-linear to elliptic with narrowly to broadly rounded apices, entire or slightly asymmetrically lobed, lobes 2–5; abaxial surfaces concealed by a dense covering of scales, these scales lanceolate, the main body 1.4–2.7 mm × 240–500 μm, the margins long-ciliate proximally and ciliolate distally; adaxial surfaces concealed by a dense covering of persistent scales, providing a silvery appearance; adaxial scales with a lanceolate main body 0.7–2.6 mm × 80–180 μm, long-ciliate, longest cilia 200–550 μm long, typically less than one half the length of the main body, 18–36 cilia per scale; sporangia containing 64 spores averaging spore ca. 45–49 μm in diam.
A
Forma de vida
Rupícola.B
Elevación
950 – 2250 mB
Ecología y Hábitat
limestone slopes in the Sierra Madre Oriental.A
Tipo de vegetación
Matorral espinosoB
Categoría IUCN
No incluidaC
Categoría NOM-059-SEMARNAT-2010
No incluidaD
Discusión taxonómica
Etymology— The specific epithet refers to both the difficulty in discovering this elusive taxon, and the dense covering of adaxial pinnae scales that largely obscure the pinnae surface.
Morphological Affinities—Astrolepis obscura can be easily distinguished from all other diploid Astrolepis species by its entire to shallowly lobed pinnae with a dense, persistent covering of lanceolate scales on the adaxial surface. Although some collections identified as A. integerrima approach this morphology, A. obscura is clearly differentiated from the type of A. integerrima ( Leibmann s. n. —K) in that it exhibits a nearly continuous covering of persistent scales on adaxial pinna surfaces, adaxial pinna scales with a greater number of cilia (18–36 vs. 10–15), and 64 (vs. 32) spores per sporangium that are significantly smaller (45–49 vs. 59–70 μm in diam). As a whole, A. integerrima comprises a morphologically variable assemblage of apomictic allotriploids, and A. obscura can be distinguished from these plants based on spore size (45–49 vs. 63–70 μm), breeding system (64 vs. 32 spores per sporangium), and genetics. One of the A. obscura specimens from Querétaro ( Díaz & Carranza 7481 ) is distinct from the remaining two known specimens in a number of respects, exhibiting shallowly lobed (vs. entire) pinnae, relatively long (to 2.6 mm) adaxial pinnae scales, and more extensive pigmentation at the base of the midrib scales. Further investigation is needed to evaluate the distinctiveness of this potentially unique lineage.
A
Morphological Affinities—Astrolepis obscura can be easily distinguished from all other diploid Astrolepis species by its entire to shallowly lobed pinnae with a dense, persistent covering of lanceolate scales on the adaxial surface. Although some collections identified as A. integerrima approach this morphology, A. obscura is clearly differentiated from the type of A. integerrima ( Leibmann s. n. —K) in that it exhibits a nearly continuous covering of persistent scales on adaxial pinna surfaces, adaxial pinna scales with a greater number of cilia (18–36 vs. 10–15), and 64 (vs. 32) spores per sporangium that are significantly smaller (45–49 vs. 59–70 μm in diam). As a whole, A. integerrima comprises a morphologically variable assemblage of apomictic allotriploids, and A. obscura can be distinguished from these plants based on spore size (45–49 vs. 63–70 μm), breeding system (64 vs. 32 spores per sporangium), and genetics. One of the A. obscura specimens from Querétaro ( Díaz & Carranza 7481 ) is distinct from the remaining two known specimens in a number of respects, exhibiting shallowly lobed (vs. entire) pinnae, relatively long (to 2.6 mm) adaxial pinnae scales, and more extensive pigmentation at the base of the midrib scales. Further investigation is needed to evaluate the distinctiveness of this potentially unique lineage.
A
Bibliografía
A. Beck, J. B. 2010: A Diploids-First Approach to Species Delimitation and Interpreting Polyploid Evolution in the Fern Genus Astrolepis (Pteridaceae). – Syst. Bot. 35(2): 223-234