Adiantum oaxacanum Mickel & Beitel
Descripción
Rhizomes short-creeping, 2–4 mm diam.; rhizome scales golden brown, 1–3 X 0.1–0.3 mm, margins sparsely denticulate; fronds spaced 3–8 mm apart, 40–100 cm long, arching; stipes atropurpureous, 25–50 cm X 2–4 mm, 1⁄2–2⁄3 the frond length, with scattered pectinate appressed scales; blades deltate to oblong, 2-pinnate, 20–35 cm wide; rachises atropurpureous, with tan, appressed, lanceolate scales mostly ca. 1–1.5 mm long, these denticulate or ciliate at margins; pinnae (1–)2–4 pairs plus a conform terminal one, alternate, 12–20 X 4–7 cm, terminal pinnules triangular and acute at tips, basal pinnules reduced, asymmetrical; pinnules 20–35 X 10–15 mm, pinnule bases ca. 90° or slightly less, apices rounded, margins finely serrulate, nonarticulate; veins free, forking, ending in small teeth; indument adaxially absent, abaxially the surfaces with scattered, tan, pectinate, hair-like scales to 0.5–1 mm long; idioblasts present on both blade surfaces, inconspicuous; sori mostly 10–14 per pinnule, along acroscopic and distal half of basiscopic margins, as well as on pinnule tips; indusia 2–4 mm long, glabrous.A
Forma de vida
TerrestreA
Ejemplar revisado
Oax (Hernández G. 1610, 1611, MEXU, NY; Hernández G. & González 1738, CAS, CHAPA, MEXU; Martínez C. 104, NY; Mickel 5132a, NY, UC, 5172, 5804, 6914, NY; Torres C. 627, MEXU). Ver (Copeland herb. s.n., 31 Jan 1938, UC; Delgadillo 12274, UC; Martínez C. 1035, XAL; Reeves R5908, ASU). Unverified, Doubtful, or Mistaken Reports. Tab (reported by Magaña, 1992, not verified, probably based on a misidentification).A
Distribución
México (país) EndémicoA
Elevación
0 – 800 mA
Ecología y Hábitat
Along stream banks and roadsides.A
Tipo de vegetación
Selva altaA
Categoría IUCN
No incluidaB
Categoría NOM-059-SEMARNAT-2010
No incluidaC
Discusión taxonómica
Among the bipinnate, idioblastic species with large pinnules, this species is distinguished by its glabrous indusia, rounded pinnule apices, and pinnule bases ca. 90° or slightly less. It appears most closely related to A. mcvaughii, of western Mexico, from which it differs primarily by the persistent narrow scales and hairs on the blades abaxially. Mickel (1992) stated that the basal pinnules of the latter were less strongly reduced than in A. oaxacanum, but this difference seems rather slight, if significant at all. Both species are closely related to A. latifolium and differ from that in the broader, round-tipped pinnules. Mickel and Beitel (1988) thought Adiantum oaxacanum to be intermediate in morphology between A. obliquum and A. amblyopteridium and possibly the fertile hybrid between these two species. Part of the evidence for hybridization was based on the fact that both putative parents and A. oaxacanum were from the same general locality, near Pochutla. This hypothesis needs testing, and it seems just as likely that A. oaxacanum has been derived from the widespread A. latifolium. Hernández & González 1738 (CAS) has prominently ciliate indusial margins, and thus deviates from other specimens seen. Martínez C. 1035 (CAS), from Veracruz, has strongly malformed spores and is possibly a hybrid involving A. latifolium and A. oaxacanum.
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Bibliografía
C. SEMARNAT 2019: MODIFICACIÓN del Anexo Normativo III, Lista de especies en riesgo de la Norma Oficial Mexicana NOM-059-SEMARNAT-2010: 101 pp. – https://www.dof.gob.mx/nota_detalle.php?codigo=5578808&fecha=14/11/2019#gsc.tab=0 [accessed 2023-05-04 06:16]