圆裂双盖蕨 yuan lie shuang gai jue

Allantodia cycloloba (Christ) Ching; A. uraiensis (Rosenstock) Ching; Diplazium latifolium T. Moore var. cyclolobum Christ; D. uraiense Rosenstock var. cyclolobum (Christ) Tagawa.

Plants evergreen, medium-sized to large. Rhizome erect, brown, ca. 1.5 cm in diam., apex like base of stipe, densely scaly; scales dark brown, linear-lanceolate, ca. 1 cm, membranous, margin black, narrow, toothed; fronds caespitose; fertile frond up to 1.4 m; stipe brown at base, upward gradually gray-stramineous, up to 60 cm, ca. 7 mm in diam., upward glabrous, somewhat quadrangular, shallowly grooved adaxially; lamina 2-pinnate, oblong-deltoid, up to 80 × 60 cm; pinnae up to 9 pairs, alternate, slightly ascending, slightly narrowed to base, apex pinnatipartite; second basal pinnae largest, oblong, ca. 40 cm; pinnules up to 13 pairs, alternate, slightly ascending, linear-lanceolate, or lower pinnules narrowed, narrowly elliptic to lanceolate, up to 10 cm, base rounded or crenate, symmetrical or nearly symmetrical, sparsely shallowly incised or pinnatilobate, apex acuminate; pinnule lobes orbicular, entire or minutely crenate; veins pinnate, visible abaxially, not prominent adaxially, veinlets 4 or 5 pairs per pinnule lobe, simple, ascending. Lamina papery, brown-green when dry, glabrous on both surfaces; rachis brown-stramineous, slightly quadrangular, glabrous, shallowly grooved adaxially; costules abaxially with sparse hairlike red-brown scales. Sori linear, ± falcate, 2-5 pairs per lobe, inframedial from costule to 1/2 or more to margin, single or double on basal acroscopic veinlets; indusia light brown, linear, membranous, opening acroscopically, persistent.

● Evergreen broad-leaved forests; 500-1000 m. Hainan, Taiwan.

Diplazium uraiense is similar to D. dilatatum but differs by the pinnule linear-lanceolate, symmetrical at base, and shallowly pinnatilobate. Some authors treat this species as a synonym of D. dilatatum (e.g., see Knapp, Ferns Fern Allies Taiwan, 449-450. 2011).