Cyrtomium adenotrichum Y. Nong & R. H. Jiang, 2024

Nong, You, Lei, Li-Qun, Zhao, Zi-Yi, Wei, Gui-Yuan, Xu, Chuan-Gui, Feng, Bin, Qu, Xin-Cheng & Jiang, Ri-Hong, 2024, Cyrtomium adenotrichum (Dryopteridaceae), a new species from Guangxi, China, PhytoKeys 243, pp. 199-207 : 199-207

Cyrtomium adenotrichum Y. Nong & R. H. Jiang sp. nov.

Figs 1 , 2 , 3 , 4

Diagnosis.

Cyrtomium adenotrichum is similar to C. nephrolepioides , C. obliquum , C. sinningense and C. calcis , but differs in its stipe sparsely glandular (vs. glabrous). In addition, it can be distinguished from C. sinningense by its scale margins fimbriate (vs. dentate), lateral pinnae 5–10 pairs (vs. 1–4 pairs), indusia margins dentate (vs. subentire); it can also be distinguished from C. nephrolepioides by its lateral pinnae 5–10 pairs (vs. 10–26 pairs), base obvious oblique (vs. cordate or sometimes obliquely cordate). It differs from C. obliquum by its scale margins fimbriate (vs. dentate), lateral pinnae 5–10 pairs (vs. 12–21 pairs), indusia margins dentate (vs. entire). It can be distinguished from C. calcis by its base obvious oblique (vs. cordate to hastate), lateral pinnae thin leathery (vs. thick leathery). Comparative morphological differences among all five species are presented in Table 1 .

Holotype.

China. Guangxi: Nandan , 24 ° 48 ' 47 " N, 107 ° 27 ' 12 " E, alt. 470 m, on the cliff at a gully; 17 March 2024; Y Nong NY 2024031701 ( GXMI!). (holotype: GXMI!; isotypes: IBK!).

Description.

Plants perennial, evergreen, 5–15 cm tall. Rhizome short and erect, together with basal stipe densely scaly. Scales brown, ovate; Leaves clustered, petiole 1–3 cm, stipe stramineous, 3–10 cm, 1 mm in diam, sparsely glandular, densely scaly; scales brown, ovate or lanceolate, margins fimbriate. scales on stipe base brown, ovate or lanceolate, membranous, ca. 8–12 × 1–3 mm, margin minutely denticulate and slightly long ciliate, upword gradually narrowed, subulate, linear-lanceolate. Lamina linear-lanceolate, 5–10 × 1.5–2 cm, base not contracted, 1 - imparipinnate; Lateral pinnae 5–10 pairs, crowded, alternate, spreading or slightly ascendant, shortly stalked, ovate or rarely deltoid-lanceolate; lower and middle pinnae 8–10 × 4–6 mm, respectively, subopposite or alternate, apex rounded, base obvious oblique, basiscopic base truncate, acroscopic base auriculate or ovate, margins entire and often slightly reflexed, sparse hairlike scales adaxially and abaxially; terminal pinna ovate, with 1 or 2 connate lobes at base, 20–35 × 15–25 mm; rachis c. 1 mm in diam, sparsely glandular, grooved adaxially, scaly abaxially; scales on rachis brown, linear to subulate, margins sparsely toothed or fimbriate; frond texture thin leathery; venation pinnate, midrib flat or slightly concave on abaxially and adaxially, lateral vein connection, indistinct, lateral veins anastomosing to form 1 or 2 rows of areoles on each side of midrib. Sori 1 row on each side of midrib; indusia margins dentate.

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 only one population with 10 individuals, and the habitat of Cyrtomium adenotrichum is fragile because it could be submerged during the rainy season.

IUCN Red List Category.

Only one population with 10 individuals of Cyrtomium adenotrichum is currently known from Nandan County, Guangxi China. Due to its rarity, the low number of individuals and habitat vulnerability, C. adenotrichum is considered to be Critically Endangered ( CR), according to the IUCN ( IUCN 2022).

Figures

Figure 1. Habitat of Cyrtomium adenotrichum Y. Nong & R. H. Jiang on cliffs at a gully (Photographed by YN).

Figure 2. Line drawing of Cyrtomium adenotrichum Y. Nong & R. H. Jiang A plant B scale C indusium (Drawn by Xin – Cheng Qu).

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. 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.

Figure 5. The distribution of Cyrtomium adenotrichum (red circle) in Guangxi, China.