内蒙铁角蕨 nei meng tie jiao jue

Type: China. Nei Mongol: Hulunbuir, Balin, Beishan, in rock crevices, 460 m, 2 Aug 1983, Y.-Q. Ma et al. 83-7 (holotype, HIMC).

Planta morphologia Asplenio tenuicaulis. Rhizoma breve adscendens vel erectum, squamis 1.5-2 mm longis et ca. 0.5 mm latis. Folia caespitosa, maturitate (4-)6-15(-20) cm longa, basi 1-3 cm lata; petiolus lamina 2-plo brevior, pro parte abaxiali basali 1/4 ad 3/4 fuscus, basi squamis eis rhizomatis similibus vestitus; lamina papyracea, anguste triangulari-ovata, basi bipinnata, paribus pinnarum suboppositarum vel alternarum 5 ad 10; jugum primum vel secundum maximum, pinnis (5-)8-12(-20) mm longis, triangularis-ovatis inaequilateris acroscopice truncatis, basiscopice cuneatis, apice obtusis, petiolulis usque ad 1 mm longis, stomatibus 49-53 µm longibus. Sori 0.8-2.5 mm longi, maturitate confluentes. Sporae exosporium 34-39 µm longum, perisporium costatum.

Plants (4-)6-15(-20) cm tall. Rhizome erect, short, apex scaly; scales brown to dark brown, triangular to narrowly triangular, 1.5-2 × 0.4-0.5 mm, base hastate-cordate, margin glandular, fimbriate or entire. Fronds caespitose; stipe green but base castaneous, brown color occasionally extending into rachis, (1-)1.5-5.5(-7) cm, with small dark brown, fimbriate scales and uniseriate hairs, subglabrous when old, adaxially sulcate; lamina triangular to narrowly triangular-ovate, (2.5-)3.5-6.5(-9) × 1-3 cm, base truncate to broadly cuneate, pinnate-pinnatifid to bipinnate, apex acute-acuminate; pinnae 5-10 pairs, subopposite to alternate, stalk up to ca. 1 mm, basal or first suprabasal pinnae pair largest, triangular-ovate, (5-)8-12 (-20) × (3-)5-7(-8) mm, base asymmetrical, acroscopic side truncate, basiscopic side cuneate, pinnate, rarely 2-pinnatifid, apex obtuse; pinnules 2 or 3 pairs, anadromous, basal pinnules free or adnate to costa, margin serrate with acute to mucronate teeth, apex obtuse. Veins obscure, veinlets 1- or 2-forked, not reaching margin. Fronds thinly herbaceous, green to gray-green or brown when dried, rachis green, only rarely with castaneous base (abaxially), adaxially sulcate, subglabrous, lamina with 3- or 4-celled uniseriate gland-tipped hairs, average guard cell length 49-53 µm. Sori 1-3 per pinnule, median on acroscopic veinlets, occasionally confluent at maturity, oval-linear, 0.8-2.5 mm; indusia whitish to pale brown, oval-linear, membranous, entire to repand, opening toward costule or costa. Spores with lophate (costate-cristate) perispore, average exospore length 34-39 µm.

● Rock crevices; 400-1800 m. Liaoning, Nei Mongol (Da Xing’an Ling), Shanxi.

This species is named after Professor Yu-Quan Ma, principal editor of Flora Intramongolica.

Asplenium mae is mainly known from the Da Xing’an Ling. It is a putative autotetraploid which probably originated via chromosome doubling in A. tenuicaule var. subvarians, which it strongly resembles. Average spore size indicates that it is probably tetraploid, but no chromosome counts are yet available. In herbaria, A. mae is either filed under A. tenuicaule, A. subvarians, A. anogrammoides, or A. sarelii.

Several names have been misapplied to this species, e.g., Asplenium subvarians by Ling et al. (in Liu, Fl. Shanxi. 1: 84-97. 1992), A. tenuicaule by Wu and Bai (Fl. Intramongol. 1: 49-117. 1985), and A. sarelii by Li and Wang (Fl. Liaoning 1: 73-79. 1988).