Ctenitis sinii (Ching) Ohwi

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 : 126

Ctenitis sinii (Ching) Ohwi ( Fig. 5 )

Basionym: Tectaria sinii Ching (1933: 22) .

Type:— CHINA. Kwangsi, Yao Shan, Loxiang, 1000 m, Sin & Whang 706 (BM-001048518, image seen, PE-01896230, image seen).

Voucher specimens examined:— VIETNAM. Lam Dong Province, Lam Ha District, Phi To Commune, Nam Ban Protection Forest, Tieu khu 245, broad-leaved evergreen forest, along stream, ca. 1290 m, 11.915° N, 108.261° E, 4 December 2018, C.- W. Chen Wade5426 ( SGN!, TAIF!) ; same locality, 2 June 2019, C.- W. Chen Wade5724 ( PHH!, SGN!, SING!, TAIF!) .

Additional specimens examined:— JAPAN. Kagoshima, Izumi City, Takaonomachi Shibahiki Nakayashiki , 2 February 1969, T. Yamanaka s.n. (TAIF-475203!) ; Kagoshima, Izumi City , T. Yamanaka s.n. (TAIF-475714!) .

Distribution:—Previously known from China, Japan, and South Korea. Our new collection from Vietnam extends the southernmost distribution of the species.

Ecology:—In Vietnam, this species was found in broad-leaved primary forest and it grows on slopes by streams.

Note:—Although five Ctenitis were recorded in Vietnam by Phan (2010), C. membranifolia Ching & Chu H. Wang (1981: 121) and C. rhodolepis (C. B. Clarke) Ching (1938: 300) were usually treated as synonyms of C. subglandulosa (Hance) Ching (1938: 302) (e.g., Dong & Christenhusz 2013). Ctenitis sinii can be distinguished from all other three species of Ctenitis in Vietnam, i.e., C. decurrentipinnata (Ching) Tard. & C.Chr. (1938: 86) , C. eatonii (Baker) Ching (1938: 291) , and C. subglandulosa by having less divided fronds (ultimate segments pinnatifid) and thicker laminae (veinlets obscure). Morphologically, C. sinii is most similar to C. dianguiensis (W.M.Chu & H.G.Zhou) S.Y.Dong (2008: 35) from southern China but can be delimited from it by having ovate scales on the rachises and costae (versus subulate in C. dianguiensis, Zhou & Chu 1995 ). We noticed that there are two specimens (Zhang et al. 7010 & 7351) collected from northern and central Vietnam, respectively, at MO that identified as C. dianguiensis . Unfortunately, the specimen images are not available online for examination. In case of that these two specimens were correctly identified, the species number of Ctenitis in Vietnam will be added to five.

Figures

FIGURE 5. Ctenitis sinii—A. Habit. B. Ovate scales on rachis. C. Stipe scales. D. Sori. E. Venation. C.-W. Chen Wade5724.