Didymoglossum wallii (Thwaites) Copel.

Chen, Cheng-Wei, Hsu, Tian-Chuan, Chao, Yi-Shan, Lu, Ping-Fong, Li, Chia-Wei, Tram, Nguyen Khanh Trinh, Nguyen, Ich Le Phuoc Thanh, Dang, Minh Tri, Luu, Hong Truong & Parris, Barbara, 2020, A newly recorded genus and twelve newly recorded species of ferns for Vietnam from Lang Biang Plateau, Phytotaxa 443 (2), pp. 121-143 : 127

Didymoglossum wallii (Thwaites) Copel. ( Fig. 7 )

Basionym: Trichomanes wallii Thwaites (1880)

Type:— SRI LANKA. Wall s.n. (holotype: K-001090167, image seen, isotype: LE-00007961, image seen).

Voucher specimens examined:— VIETNAM. Khanh Hoa Province, Khanh Vinh District , Son Thai, 800–1000 m, 25 December 2014, T.- C. Hsu 7385 ( SGN!, TAIF474838 !) ; Lam Dong Province, Da Huoai District , Deo Bao Loc, Duc Me An Binh, 623 m, 11.451 N, 107.709 E, T.- C. Hsu 10783 ( SGN!, TAIF!) ; same locality, 1 June 2019, C.- W. Chen Wade 5720 ( PHH!, SGN!, SING!, TAIF!, TNS!) ; Lam Dong Province, Lam Ha District, Phu Son Commune, Nam Ban Protection Forest , the valley near Phu Son Lam restaurant, Tieu khu 239, 1205 m, 11.916° E, 108.172° N, 27 November 2018, P.- F. Lu 31597 ( SGN!, TAIF!) ; same locality, 3 June 2019, C.- W. Chen Wade 5742 ( TAIF!) ;

Additional specimens examined:— CHINA. Hainan Province, Ledong Li Autonomous County, Jianfengling National Forest Park, 700–1000 m, 24 February 2012, T.- C. Hsu 5411 (TAIF-391875!).

Distribution:—Previously only known from Sri Lanka (type locality) and Hainan Island of China.

Ecology:—In Vietnam, this species has been found in damp valley under evergreen broad-leaved forests. There it grows as a lithophyte on vertical boulders by streams.

Note:—In Vietnam, Didymoglossum is a rather small group and there are only four other species in addition to D. wallii : D. beccarianum (Ces.) Senterre & Rouhan (2017: 210) , D. bimarginatum (Bosch) Ebihara & K.Iwats. (2006: 236) , D. henzaianum (Parish ex Hook.) Mazumdar (2014: 297) , and D. sublimbatum (Müll.Berol.) Ebihara & K.Iwats. (2006: 236) . Didymoglossum wallii belongs to subgenus Didymoglossum following Ebihara et al. 2006 and is morphologically most similar to D. beccarianum but differs in having stellate hairs on lamina margin and more elongated fronds (versus rounded in D. beccarianum ).

Figures

FIGURE 7. Didymoglossum wallii—A. Habit. B. Fertile frond (backlight). C. Venation (backlight). D. Enlarged frond showing marginal stellate hairs. E. Rhizome and sterile fronds (backlight). C.-W. Chen Wade5720.