洞生耳蕨 dong sheng er jue

Plants evergreen. Rhizome ascending, 0.4-0.8 cm, densely covered with scales; scales brown, linear or subulate, 1-1.3 mm; roots brown when dry, up to 9 cm, 0.2-0.5 mm in diam. Fronds 3-7 per rhizome, (4-)6-10 cm; stipe green, 1-2.5(-4.5) cm, 0.2-0.9 mm in diam. at midpoint; basal stipe scales brown, dull, lanceolate, 3-4.5 × 0.4-0.9 mm, papery, margins with few cilia, apices acuminate or caudate; distal stipe scales similar but narrower, varying in size, brown, dull, lanceolate with dilated bases, papery, margins regularly shortly ciliate, apices caudate. Lamina 1-pinnate, shiny adaxially, oblanceolate, 4.2-9.4 × 1.1-1.4 cm at midpoint, 1.2-1.7 cm wide at broadest part, contracted toward base, acute; rachis 0.3-1 mm in diam. at midpoint, without proliferous bulbils; scales of rachis brown, dull, subulate with dilated bases, 1.6-3.6 × 0.3-0.6 mm at base, varying in size, papery, margins regularly shortly ciliate, apices caudate. Pinnae 10-20 pairs, approximate, ascendant, basal two pairs 5-8 mm apart, basal pinnae deltoid-ovate, median pairs 3.7-6.2 × 2.5-5 mm, largest pairs 4-7 × 2.6-5.3 mm and located slightly above middle of lamina, alternate, oblong, shortly stalked with stalks 0.2-0.5 mm, acroscopic base slightly auriculate, basiscopic base straight and often forming a 75°-120° angle with rachis, apices obtuse, acroscopic margin repand; abaxially scaly, adaxially glabrous; microscales on abaxial surface subulate without dilated base (narrow-type microscales), (0.3-)0.5-1.8 mm, base ca. 0.1 mm wide, with few tortuous cilia on margin of base; frond texture papery; venation pinnate; midrib slightly raised abaxially, flat adaxially; lateral veins free, 4 or 5 pairs from midrib per pinna, nearly opposite; each lateral vein further dichotomous, slightly raised and distinct abaxially, indistinct adaxially. Sori terminal on veins of distal pinnae, (1-) 4-8 per fertile pinna, close to pinna margin, center of sorus 1-1.6 mm from pinna margin; indusia brown, ca. 0.9 mm in diam., fimbriate. Spores circular in polar view, elliptic in equatorial view, dark brown when fresh, ca. 39.1 × 40.6 µm (polar axis × equatorial axis): perispore sculpturing verrucate.

● Inside karst caves; ca. 800 m. S Guizhou (Libo).

Polystichum cavernicola and P. speluncicola share similar stature, but they can be easily distinguished from each other. Polystichum cavernicola has narrow-type microscales on the abaxial laminar surface, its pinnae are papery and have rounded acroscopic bases, and the broadest part of the lamina is located medially, whereas P. speluncicola has broad-type microscales on the abaxial laminar surface, its pinnae are nearly leathery and have auriculate acroscopic bases, and the broadest part of the lamina is located above the midpoint.