Diplazium siamense C. Christensen (1931: 332)

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 : 51

23. Diplazium siamense C. Christensen (1931: 332) . Fig. 29 .

Type: THAILAND. Chiang Mai, Summit of Doi Chom Cheng, 1500–1650 m, Rock 1507 (holotype GH) .

Plants terrestrial. Stems erect, 3–4 cm diameter, apex densely scaly; scales 10.0–12.0 × 1.0– 1.5 mm, linear, long tail at apex, brown, margin thick and toothed. Fronds 0.85–1.2 m, pinnate; petioles 30–50 cm, 5–8 cm diameter, deep green, densely scaly at base. Laminae up to 55–70 × 30–40 cm, oblong in outline; terminal pinna distinct, 18–20 cm long, gradually narrowing towards attenuate apex, margin lobed; lateral pinnae 6–8 pairs, alternate, 20–25 × 3.5–4.0 cm, linear-oblong, apex acuminate, base subtruncate, margin lobed; lobe half way to midrib, stalked; stalks 1.5–2.0 cm; rachis and costa often bearing minute scales; veins free, pinnate, veinlets 8–9 pairs, mostly simple. Sori 3–4 mm, elongate along veinlets, close to main vein. Spores monolete, 35–40 × 22.5–27.5 µm, bilateral, concavo-convex to plano-convex, perispore present; ornamentation: prominent wing folds.

Thailand: —NORTHERN: Chiang Mai (Doi Suthep, Mae Wang), Chiang Rai (Doi Pacho), Phitsanulok (Phu Hin Rong Kla, Phu Rom Rot), Nan (Doi Phuka, Khao Nok), Phrae (Mae Sai); NORTH-EASTERN: Phetchabun (Phu Miang), Loei (Na Haew, Phu Luang, Phu Suan Sai).

Distribution: — China.

Ecology: —On humus-rich mountain slopes in mixed or evergreen forests at 850–1,500 m elev.

Specimens Examined:— THAILAND. Phitsanulok, Phu Hin Rong kla, AR 69 (BCU); no locality, D.J. Middleton et al. 4926 (PSU); Loei, Phu Suan Sai, D.J. Middleton et al. 5115 (PSU); loei, Phu Luang, E. Hennipman 3621 (L); no locality, H. Koyama, H. Terao & T. Wongprasert T33676 (BKF); Chiang Mai, Mae Wang, J.F. Maxwell 03-99 (L); Chiang Mai, Doi Suthep, J.F. Maxwell 87-791 (L); K. Iwatsuki T4462 (BKF, L); Prae, Mae Sai, K. Winit 959 (BKF); Phitsanulok, Phu Hin Rong kla, P. Pongkai 16 (BCU); ibis., P. Pongkai 17 (BCU); Chiang Rai, Doi Pacho, K. Iwatsuki & N. Fukuoka T3681 (L); Nan, Doi Phuka, P. Pongkai 9 (BCU); Nan, Doi Phuka, P. Pongkai 148 (BCU); Chiang Mai, Doi Inthanon, P. Srisanga & P. Suksathan 3269 (QBG); Nan, Doi Phuka, T. Boonkerd 1574 (BCU); Petchchabun, Phu miang; T. Shimizu et al. T11367 (L); Nan, Khao Nok, W. La-ongsri et al. 1987 (QBG); Loei, Na Haew, W. Nanakorn 3875 (QBG).

Figures

FIGURE 29. Diplazium siamense C.Chr. A, lamina. B, a part of pinna with sori. C, scale showing toothed and black marginal cells. P. Pongkai 17 (BCU).