独山双盖蕨 du shan shuang gai jue

Allantodia dushanensis Ching ex W. M. Chu & Z. R. He, Acta Phytotax. Sin. 36: 379. 1998.

Plants small to medium-sized. Rhizome ascending, brown, ca. 5 mm in diam., with fleshy brown roots, apex densely scaly; scales brown, lanceolate, ca. 3 mm, membranous, entire; fronds caespitose. Fertile fronds 25-50 cm; stipe light green-stramineous, up to 23 cm, ca. 2 mm in diam., base with sparse lanceolate brown scales, upward glabrous, grooved adaxially; lamina 1-pinnate with pinnatifid to pinnatipartite pinnules, or base nearly 2-pinnate, ovate-deltoid or subdeltoid, 10-30 × 8-20 cm at base, apex acuminate; pinnae 6-10 pairs, alternate, ascending, lanceolate, up to 11 × 4 cm at base, base asymmetrical, acroscopically auriculate, basiscopically cuneate, with stalk up to 5 mm, pinnatifid to pinnatisect, apex acuminate; pinna lobes 8 pairs, ascending, contiguous, ovate or oblong, lobe margin sparsely thinly dentate, apex rounded or acute; basal pinna lobes up to 2 × 1 cm, sometimes nearly completely free, connate to each other, with narrow wings; veins not prominent adaxially, nearly visible abaxially, pinnate, veinlets in pinna lobe 1-7 pairs, ascending, mostly simple, or basal acroscopic veinlets usually bifurcate. Lamina herbaceous, gray-green when dry, glabrous on both surfaces; rachis green-stramineous, glabrous, shallowly grooved adaxially. Sori linear, slightly curved, 3-6 mm, 2-5 pairs per each lobe, single or double; indusia brown, linear, thickly membranous, entire, persistent. Spores hemispherical, perispore prominent, few rugate.

● Rock crevices on calcareous hills; 600-900 m. Guangxi (Longzhou), Guizhou.

Diplazium dushanense is similar to D. lobulosum but differs by the pinnae fewer, ca. 8 pairs, pinnatifid to pinnatipartite, and sori 2 or 3 pairs per pinna lobe; in D. lobulosum the pinnae are 22 pairs, pinnatilobate, and sorus single in pinna lobe.