西藏瓦韦 xi zang wa wei

Lepisorus niger Ching; L. pseudoangustus Ching.

Plants 15-35 cm tall. Rhizomes creeping, 1.5-2.5 mm in diam., densely scaly; scales brown with pale margins, linear-lanceolate, 3-5 × 0.7-1.2 mm, margin entire or denticulate, apex often long and filiform, opaque except for marginal 1 or 2 rows of paler, transparent lumina. Fronds 0.5-1.5 cm apart; stipe straw-colored, 1-5 cm, 1-1.5 mm in diam., base with 3 vascular bundles arranged in a triangle; lamina grayish green to grayish yellow, linear-lanceolate to lanceolate, 12-33 × 0.5-1.8 cm, widest at middle, thinly leathery when dried, sparsely scaly, scales small, opaque or transparent, base attenuate, long decurrent, margin straight or slightly revolute, apex long caudate; costa raised on both sides, veinlets obscure. Sori on distal 1/2-2/3 of lamina, midway between costa and margins, orbicular or elliptic, 2-4 mm in diam.; paraphyses brown, suborbicular, 0.3-0.5 mm in diam., margin entire; lumina dense, center thickened, opaque or transparent. Spore surface deeply and sparsely foveolate.

● On tree trunks or in rock crevices in dense forests; 1900-3700 m. Sichuan, Xizang, Yunnan.

Lepisorus contortus, L. thunbergianus, and L. tibeticus are widely distributed species in China, closely allied to each other and very difficult to distinguish. Lepisorus tibeticus is relatively large with laminae usually 22-33 cm, whereas the lamina is not more than 18 cm in L. thunbergianus. The rhizome scales of L. thunbergianus are linear-lanceolate, and opaque except for one or two rows of transparent lumina at margin, while the scales of L. contortus have a broad base and are transparent except for one or two rows of opaque lumina in center. We checked more specimens and found L. contortus and L. thunbergianus to be altitudinally vicarious, the former at higher elevations relative to the latter. Lepisorus tibeticus is a more difficult species to define: the scales are linear-lanceolate, often with a long and filiform apex, while the size of the opaque center varies continuously with elevation. For convenience we have treated the specimens from montane forest in Sichuan, Yunnan, and Xizang as L. tibeticus.