﻿Cyrtomiumadenotrichum (Dryopteridaceae), a new species from Guangxi, China

﻿Abstract Cyrtomiumadenotrichum Y. Nong & R.H. Jiang (Dryopteridaceae), a new species from Guangxi, China, is described and illustrated. This new species is similar to C.nephrolepioides (Christ) Copel., C.obliquum Ching & K. H. Shing ex K. H. Shing, C.sinningense Ching & K. H. Shing ex K. H. Shing and C.calcis Liang Zhang, N.T.Lu & Li Bing Zhang in having erect rhizomes, dense, leathery lamina and rounded sori, but it can be easily distinguishable by its stipe sparsely glandular, base obvious oblique, basiscopic base truncate, acroscopic base auriculate or ovate.


Introduction
Cyrtomium (Presl 1836) was founded upon the basis of Polypodium falcatum (Linnaeus 1781), originating from Japan.It comprises approximately 40 recognized species, the majority of which are found in East Asia, with a particular concentration of diversity centered in Southwest China.Within this group, 31 species are native to China (Zhang and Barrington 2013).Cyrtomium ser.Falcata Ching & Shing (Shing 1965), which was not confirmed as monophyletic in an earlier molecular study conducted (Lu et al. 2005), is distinguished by its leathery leaves and pinnae, which possess intact (occasionally repand) and thickened margins.Notably, all species belonging to this series can be located in China, except for C. elongatum S.K.Wu & P.K.Lôc (Wu et al 2005) and most of them are naturally distributed in limestone regions.Within the past decade, more new species of Cyrtomium have been discovered in Vietnam and China (Lu et al 2023;Nong et al. 2023).
During our field surveys conducted in Nandan County, Guangxi, in March 2024, we encountered a unique population of Cyrtomium that exhibited morphological similarities to the species C. nephrolepioides (Christ) Copel.(Copeland 1929)

Materials and methods
The new species was described based on field observations made in March and examination of herbarium specimens at GXMI.Other related Cyrtomium species were examined based on online images from Kew Herbarium Catalogue (http://apps.kew.org/herbcat/gotoHomePage.do) and JSTOR Global Plants (http://plants.jstor.org/)and PE, IBK and KUN.Morphological characters that distinguish it from all other species in the genus of Cyrtomium are used.We also observed living plants of the new species.We observed characters of rhizome, leaves, pedicels, stipe, lamina, scales, sori, indusia.

Taxonomy
Etymology.The specific epithet refers to the stipe sparsely glandular of the new species.
Distribution and habit.Known only from the north of Guangxi, China (Fig. 5).It has been mainly found on cliffs at a gully at elevations of 470 m.We found Figure 1.Habitat of Cyrtomium adenotrichum Y. Nong & R.H. Jiang on cliffs at a gully (Photographed by YN).

Figure 3 .
Figure 3. Cyrtomium adenotrichum Y. Nong & R.H. Jiang A, B plant C, D lamina (adaxially and abaxially view) E, F sori and indusia G, H terminal pinna (adaxially and abaxially view) I lateral pinnae (abaxially view, showing: margins entire and often slightly reflexed) J stipe (sparsely glandular) K curled leaves L, M, N scales O curled leaves (sparsely glandular) (Photographed and edited by You Nong).

Figure 4 .
Figure 4. Cyrtomium specimens of the new taxon and three morphologically related species A type specimen of Cyrtomium adenotrichum B C. nephrolepioides C type specimen of C. obliquum, and D type specimen of C. sinningense.