Diplazium conterminum Christ (1905: 67)

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 : 14

3. Diplazium conterminum Christ (1905: 67) . Fig. 6 .

Type: VIETNAM. Annam, vallée du Long-Gianh, Cadière 88 (lectotype P02143203 !, designated by Pacheco & Moran (2003: 91)) .

Plants terrestrial. Stem long creeping, 0.5–1.0 cm diameter, densely scaly on younger part; scales 10–12 × 1.0– 1.2 mm, linear with long tail apex, dark brown to nearly black, margin thick and toothed. Fronds about 1 m, bipinnate; petioles up to 50 cm, 0.5–1.0 cm diameter, glabrous, brown, dark at lower portion. Laminae 47–53 × 38–42 cm, subdeltoid in outline, glabrous, papyraceous, dark green, terminal pinna not distinct; lateral pinnae 6–8 pairs, alternate, 27–30 × 10–15 cm, long stalk, up to 4 cm, gradually narrowing towards acute apex; pinnules 8–10 pairs, alternate, 6–8 × 2.0– 2.5 cm, sessile or shortly stalked, oblong, apex acuminate, base cordate or subtruncate, margin crenate to lobed; veins 4–5 pairs, pinnate. Sori 1–2 mm, oblong, usually in middle of each veinlet or submarginal, indusiate; indusia thin but firm; spores monolete, 47.5–57.5 × 32.5–37.0 μm, bilateral, concavo-convex to plano-convex, perispore present; ornamentation: labryrinth.

Thailand: —NORTHERN: Chiang Mai (Doi Chiang Dao), Phitsanulok (Phu Hin Rong kla, Phu Miang,); SOUTH-EASTERN: Chanthaburi (Khao Soi Dao); PENINSULAR: Nakhon Si Thammarat (Khao Luang).

Distribution: — China, Japan and Vietnam.

Ecology: —On mountain slopes in dense forests at elevations of 900–1,500 m.

Specimens Examined:— THAILAND. Chantaburi, Khao Soi Dao, K. Iwatsuki & N. Fukuoka T7204 (L); Phitsanulok, Phu Hin Rong kla P. Pongkai 15 (BCU); Phitsanulok, Phu Hin Rong kla, Mun Dang Waterfalls, P. Pongkai 109 (BCU); Phitsanulok, Phu Miang, T. Shimizu et al. T11603 (BKF, L). CHINA. Guizhou, anonymous 1791 (PE).

Figures

FIGURE 6. Diplazium conterminum Christ. A, pinna. B, a part of pinnule with sori. C, scale showing toothed and black marginal cells. P. Pongkai 15 (BCU).