Diplazium arisanense Hayata, Icon. Pl. Formosan. 4: 212. 1914.

Rhizomes short, erect, apex densely clothed with pale brown, linear-lanceolate scales. Fronds caespitose; fertile fronds 45-60 cm; stipe blackish brown, upward light purplish red, 25-30 cm, ca. 2.5 mm in diam., base densely scaly, upward glabrate; lamina 2-pinnate, deltoid-ovate, 30-35 × ca. 18 cm at base, base broader, apex slightly abruptly narrowed, long acuminate; pinnae ca. 10 pairs, alternate, ascending, shortly stalked (stalk ca. 2 mm), basal pinnae not shortened, slightly narrowed toward base, lower pinnae subfalcate-lanceolate, ca. 13 × 3-3.5 cm at middle, base rounded-truncate, slightly unequally sided, pinnate, apex long acuminate; pinnules ca. 14 pairs, basal pinnules opposite, upper pinnules alternate, ascending, sessile; lower pinnules oblong, 1.3-1.5 × 5-6 mm at base, base inequilateral, truncate, somewhat auriculate on acroscopic side, cuneate, almost not decurrent on basiscopic side, margin entire or somewhat repand, with small teeth toward apex, apex obtuse and mucronate; veins inconspicuous adaxially, visible abaxially, pinnate in pinnules, lateral veins ca. 7 pairs, oblique, mostly forked, but pinnate in auriculate lobes. Lamina papery when dried, pale green, glabrate on both surfaces; rachis and costae abaxially slightly purplish, sparsely shortly hairy, with subulate spines on adaxial side at base of costa or costule. Sori elliptic, 3 or 4 pairs per pinnule, biseriate on both sides of costules, subcostular; indusia brownish, oblong, sometimes reniform at base of pinnules, membranous, entire, often fugacious at maturity. Perispore surface without folds. 2n = 160.

Broad-leaved forests; 600-2500 m. Taiwan [Japan].