Etymology From oto, ear. See description of the pinnae.

Description Rhizome: erect, short, scales linear-lanceolate, 0.8--1 cm long, black or blackish brown, polished.
Frond: 80 cm high by 30 cm wide, deciduous, monomorphic, blade/stipe ratio: 1:1 to 3:2.
Stipe: burgundy, the color carried to rachis and costa, dark brown at swollen, laterally spinous base, old stipe bases persistent, scaly at base, 8-10 mm long, nearly black, lustrous, vascular bundles: 2, lunate, uniting to a U-shape above.
Blade: 2-pinnate, triangular, papery, glabrous.
Pinnae: 8 to 15 pair, nearly sessile, lanceolate, 2--4 cm broad, long-pointed at apex; pinnules eared outward at the base; costae with prominent spines on the upper side at costule-base ; margins serrate; veins free, forked, prominent on the lower surface.
Sori: elongate to gently curved, near the costule, indusium: shape as for the sori.

Culture Habitat: no report found. Distribution: Japan, Korea, China. Hardy to -30°C, USDA Zone 4.

Distinctive Characteristics the burgundy rachis and costa provide immediate recognition

Synonyms
Asplenium otophorum Miq.
Diplazium otophorum (Miq.) C. Chr.
Athyrium rigescens Makino