台湾轴脉蕨 tai wan zhou mai jue

Dryopteris kusukusensis Hayata, Icon. Pl. Formosan. 4: 157. 1914; Ctenitis kusukusensis (Hayata) H. Itô; Ctenitopsis hainanensis Ching & Chu H. Wang; C. kusukusensis (Hayata) C. Christensen ex Tardieu & C. Christensen; C. kusukusensis var. crenatolobata Tagawa; C. tamdaoensis Ching; D. membranoides Hayata; Thelypteris kusukusensis (Hayata) C. M. Kuo.

Plants terrestrial, 40-100 cm tall. Rhizome erect, short, 1-1.5 cm in diam., densely scaly at apex; scales dark brown with narrow paler margin, broadly lanceolate, 4-6 mm, rigidly membranous, entire, apices acuminate. Fronds clustered; stipe dark brown to dark stramineous, 20-50 cm, 3-5 mm in diam. at base, grooved above, sparsely to densely clothed with articulate brown to light gray hairs, lower part with sparse dark brown scales like on rhizome. Lamina tripinnatifid, bipinnatipartite upward, dark brown or green when dried, elliptic to elliptic-lanceolate, 30-50 × 15-25 cm, (thickly) papery, abaxially glabrous, adaxially with sparse caducous brown or light gray articulate hairs, base subcordate, apex long acuminate to caudate (then tail 2.5-3 cm, subentire); rachises, costae, and main veins brown to dark stramineous, densely clothed with long, brown or gray articulate hairs; pinnae 10-12 pairs, subopposite on lower part, alternate upward, interval 4-5 cm; basal pinnae largest, obliquely triangular, 10-20 × 6-15 cm, stalk 3-5 mm (subsessile upward), (long) acuminate, pinnatipartite to forming 1-3 pairs of separate large pinnules at base; middle pinnae (linear) lanceolate, 8-17 × 2.5-3 cm, bases cuneate, apices long acuminate to caudate, pinnatipartite to 2/3-3/4 toward costa, often with subseparate pinnules below; basal basiscopic pinnules lanceolate, 4-12 × 1-2.5 cm, bases rounded-cuneate, mucronate, apices long acuminate to caudate, pinnatipartite to 2/3 toward costa; lobes 8-15 pairs, interval 1-3 mm, oblique, triangular-elliptic to broadly lanceolate, 6-10 × 3-7 mm, margin mucronate, entire or undulate to toothed, ciliate. Veins pinnate, free, forked or simple, inconspicuous above, raised below. Sori orbicular, 3-8 pairs terminal on veinlets near margin, regular in 1 or 2 rows beside main veins; indusia dark brown, orbicular-reniform, membranous, glabrous, entire, persistent.

Near streams in valley forests; 100-700 m (in Taiwan). Guangdong, Guangxi, Hainan, Taiwan, Yunnan [Vietnam].

Ctenitopsis hainanensis appears to differ from Tectaria kusukusensis only in its smaller stature and caudate pinna apices. It may well be an unusual population in Hainan, but one of us (Christenhusz) has not found sufficient evidence for its status as a separate species and thus refrains from making a nomen novum in Tectaria for this taxon.