尖顶耳蕨 jian ding er jue

Plants evergreen. Rhizome erect, short, 1-2.5 cm, rhizome apex and stipe base densely scaly; scales reddish brown, ovate or ovate-lanceolate, up to 5 × ca. 2 mm, thickly membranous, with short fine teeth, acuminate. Fronds 23-55 cm; stipe stramineous, 7-20 cm, 0.8-1.2 mm in diam., distal stipe sparsely scaly; scales varying in size, reddish brown, membranous; larger scales similar to basal stipe scales; smaller scales lanceolate or broadly ovate, margins with irregular thick cilia, apices long acuminate or shortly caudate; scales marginate with cells along margins often irregularly curved. Lamina 1-pinnate, grayish green when dry, adaxially darker, linear-lanceolate or nearly linear-lanceolate, rarely nearly narrowly deltoid, 11-30 × 3-10 cm at middle, slightly contracted or not at base, acuminate or long acuminate; rachis stramineous, without proliferous bulbils, sparsely scaly abaxially; microscales reddish brown, narrowly lanceolate or broadly ovate, with sparse long teeth, long caudate. Pinnae 9-30 pairs, nearly falcate or oblong-lanceolate, middle pairs 1.5-5 cm × 7-15 mm at middle, apices acuminate and spinulose, bases asymmetrical, acroscopic base obviously wider, slightly raised and auriculate; auricles low and broadly deltoid, with 1-3 shallow teeth and only 1 or 2 teeth spinulose, sometimes only weakly acute or obtuse at apex of teeth, acroscopic margins of pinnae substraight, with sparse low obtuse teeth or nearly repand, basal basiscopic margins narrowly cuneate, truncate or slightly curved, margins entire, distal basiscopic margins curved upward, with sparse low obtuse teeth; adaxially glabrous, midrib concave, abaxially sparsely covered with lanceolate light brown microscales; frond texture papery; venation pinnate, distinct and slightly raised abaxially, indistinct adaxially; lateral veins nearly reaching pinna margin, pinnate above midrib from base to apex, dichotomous or simple, simple or dichotomous below midrib. Sori terminal on shorter veinlets, in 1 row on each side of midrib, medial, 1-15 above midrib, fewer than 8 or absent below midrib; indusia present, reddish brown, with regular fine teeth, evanescent.

Limestone crevices in montane broad-leaved evergreen forests, limestone caves; 800-1700 m. NW, SW, and W Guangxi, C Guizhou (Qingzhen, Ziyun), W Hunan (Baojing), SE Yunnan [N Vietnam].

The distribution record for Vietnam is new.