Diplazium mettenianum (Miq.) C. Christensen (1906: 236)

Pongkai, Puttamon, Zhang, Li-Bing, Boonkerd, Thaweesakdi & Pollawatn, Rossarin, 2023, Revision of the fern genus Diplazium (Polypodiales: Athyriaceae) in Thailand, Phytotaxa 631 (1), pp. 1-69 : 32

13. Diplazium mettenianum (Miq.) C. Christensen (1906: 236) . Fig. 16 .

Asplenium mettenianum Miquel (1867: 174) .

Type: JAPAN. Textor s.n. ( L0052441 !) .

Plants terrestrial. Stems short creeping, 1.0– 1.5 cm diameter, covered with scales throughout; scales 8–10 × 0.8–1.0 mm, linear-lanceolate, concolourous, black, margin minutely toothed. Fronds up to 1 m, unipinnate; petioles up to 50 cm, 6–7 mm diameter, glabrous, deep green, black at lower portion. Laminae 30–50 × 30–40 cm, terminal pinna not distinct, ovate-oblong in outline, apex acuminate, glabrous, thinly chartaceous, deep green when living, brown when dry; lateral pinnae 8–10 pairs, alternate, 20–25 × 2–4 cm, oblong, apex acuminate, base cordate, lobed at margin; lobes about ¼ way to costa, apex round to obtuse, margin subentire to serrate, stalked; stalks 1.5–2.0 cm, longest at lower pinnae; upper pinnae rather suddenly becoming smaller, adnate and gradually decurrent at base; veins pinnate, veinlets 4–5 pairs, free. Sori 4–5 mm, oblong, elongate along veins, longest at lower veinlets of vein group, diplazoid. Spores monolete, 66–68 × 39–42 μm, bilateral, concavo-convex to plano-convex, perispore present; ornamentation: prominent wing folds.

Thailand: —NORTH-EASTERN: Loei (Phu Kradueng).

Distribution: — China, Taiwan Island, Japan and Vietnam.

Ecology: —On humus-rich slopes in dense forests at about 1,100 m elev.

Specimens Examined:— THAILAND. Loei, Phu Kradueng, E. Hennipman 3691 (B, L); Loei, Phu Kradueng, P. Pongkai 18 (BCU); ibis., P. Pongkai 19 (BCU); ibis., P. Pongkai 20 (BCU); Loei, Phu Kradueng, P. Jadprajong 8 (BKF); ibis., P. Jadprajong 9 (BKF); ibis., P. Jadprajong 11 (BKF); ibis., P. Jadprajong 71 (BKF); ibis., P. Jadprajong 236 (BKF); Loei, Phu Kradueng, P. Pongkai 23 (BCU); Loei, Phu Kradueng, T. Boonkerd 1113 (BCU, K). CHINA. Hong Kong, S.Y. Hu 9132 (K); No locality, Taam 321 (K). JAPAN. Kagoshima, A. Ebihara et al. KS2007-153 (PE); Kumamoto, A. Ebihara et al. KS2007-211 (PE); Tinlegang between Thimphu, B. Bartholomew et al. 3768 (PE); Honshu, E. Zogg et al. 11394 (PE); Kyushu, J. Murata at al. 2419 (PE); no locality, M. Togasi (BM); Shikoku, T. Matsumoto et al. 61630 (QBG); Yunokawa, T. Miyazaki 1011799 (PE); no locality, T. Miyazaki 903136 (PE); Honshu, T. nakaike 26 (B). TAIWAN ISLAND. Nantou, E. Schuettpelz 1017C (BM); Nantou Yu-Chich, D.E. Boufford & B. Bartholomew 25003 (BM, MICH).

Figures

FIGURE 16. Diplazium mettenianum (Miq.) C.Chr. A, lamina. B, a part of pinna with sori. C, scale showing entire and not black marginal cells. P. Pongkai 20 (BCU).