Polystichum tenuius (Ching) Li Bing Zhang, 2012

Zhang, Li-Bing, 2012, Taxonomic and nomenclatural notes on the fern genus Polystichum (Dryopteridaceae) in China, Phytotaxa 60 (1), pp. 57-60 : 59

Polystichum tenuius (Ching) Li Bing Zhang , comb. nov.

Basionym:— Cyrtogonellum tenuius Ching (1938: 329 , t. 7: 2, as “ tenuium ”). Type:— VIETNAM. Tonkin: Massif du Pia-Ouac, July 1922, Herb. de l'ecole superieure d'agriculture et de sylviculture (Hanoi) 552 ex Herb. Christensen (holotype BM-001048798!) .

Heterotypic synonym: — Cyrtogonellum caducum Ching (1938: 330 , t. 7: 3). Type:— CHINA. Guangxi: Lan Lon , east of Lin Yen Xian , in limestone niches, 1133 m, 2 August 1928, R. C. Ching 6649 (lectotype PE-00984598!, isolectotypes LBG-00117388!, LBG-00117389!, LBG-00117390!, PE-00984597!, here designated) .

Note: — The type specimen in the protologue was listed as “ Ching 664 ”. This is possibly a printing error for “ Ching 6649 ”. The specimens of R. C. Ching with the number 6649 at PE bear the author’s handwriting and are labelled with “Typus”. The collection date (2 August 1928) and identification date (30 March 1938) of these specimens do not contradict the publication date of the species (1 November 1938). There are two original type specimens at PE, one of which is chosen as lectotype of the name here. Three additional duplicates at LBG were located .

Heterotypic synonym: — Cyrtogonellum salicifolium Ching ex Y.T.Hsieh in Hsieh & Li (1989: 16). Type:— CHINA. Chongqing: Nanchuan Xian , Jinfo Shan , in sylvis, 1000 m, J. H . Xiong 81829 (holotype PE) .

Heterotypic synonym: — Cyrtogonellum falcilobum Ching ex Y.T.Hsieh , in Hsieh & Li (1989: 17). Type:— CHINA. Guizhou: Pintang Xian , Xiangshuidon , in fissuris saxosis, 1000–1200 m, X. Y . Hou 1852 (holotype PE) .

Cyrtogonellum caducum Ching and C. tenuius Ching are published in the same paper and thus have equal priority. When they are synonymized with each other and the species is transferred to Polystichum , the second name is chosen, because the epithet “ caducum ” is blocked by Polystichum caducum (T.Moore) Diels (1899: 194) .

This species occurs in Chongqing, Guangxi, Guizhou, Hunan, Sichuan, and Yunnan, China and northern Vietnam.