Polystichum cretaceum Xiaohua Chen & Y.F.Gu, 2025

Chen, Xiao-Hua, Shu, Jiang-Ping, Xu, Yi-Da, Liu, Hong-Mei, Chen, Li-Jun, He, Jiao, Zheng, Xi-Long & Gu, Yu-Feng, 2025, Polystichum cretaceum (Polystichum sect. Cyrtogonellum, Dryopteridaceae), a new fern from Guangxi, China, Phytotaxa 690 (2), pp. 276-284 : 279-282

Polystichum cretaceum Xiaohua Chen & Y.F.Gu sp. nov. ( Fig. 2 ).

Type:— CHINA. Guangxi: Baise City , Napo County, 105°51′22.174″E, 22°57′30.171″N, elev. ca. 1032 m, 20 May 2023, Chen Xiao-hua & Li Min-yu YYH19982 (Holotype PE!; isotype NOCC!) .

Diagnosis:—It is characterized with a simple lamina, or occasionally pinnatilobate at the base, whereas other species consistently exhibit 1-pinnate laminae. It resembles P. fraxinellum but differs in having oblong-rectangular, entire, and obtuse-apex lateral pinnae, in contrast to the ovate-lanceolate lateral pinnae of P. fraxinellum , which feature slightly curved, distally basiscopic margins that are regularly shallowly incised-toothed with acuminate apices. Additionally, the venation in P. cretaceum is free, whereas it is reticulate in P. fraxinellum ( Table 1).

Evergreen plants, 4.3–8 cm tall. Rhizome erect or ascending, short, 0.5–0.8 cm in diam, densely covered with lanceolate brown scales. Fronds clustered; petiole straw-colored, groove, 2–3 cm long, 0.1–0.2 cm in diameter; basal portion densely covered with scales; basal scales ovate-lanceolate, caudate, brown, edges with lighter color, apex with caudal tip and margins with sparse ciliated; distal stipe scales similar but narrower. Lamina triangular to broadly lanceolate, simple or one lateral pinnules at base or 1-pinnate; simple lamina entire or undulate or slightly repand, coriaceous, elliptic, apex of lamina rounded, base of lamina cordate; 1-pinnate lamina 2.5–3.5 cm long, ca. 1–1.5 cm wide, apex obtuse, pinnae 2–4 pairs, oblong-rectangular, entire, shortly stalked, base asymmetric and cuneate, auricles indistinct; adaxially pilose or glabrous, abaxially sparsely lanceolate scaly. Sori terminal on lateral veins, rounded. Indusium indusiate, orbiculate, peltate. Spores 40–50 μm in diam., the polar view is nearly round, the equatorial view is oval, the outer perispore surface ornamentation is fenestrate, and the spore is smooth after removing the outer perispore ( Fig. 3 ).

Distribution: —Napo County, Baise City, Guangxi Zhuang Autonomous Region, China.

Ecology and conservation: — Polystichum cretaceum is currently known only from its type locality in Napo County, Baise City, Guangxi Zhuang Autonomous Region, China, where approximately 50 individuals have been documented. It grows on damp, shaded limestone walls along winding mountain roads. The region’s high rainfall and frequent landslides pose significant threats to the survival of the species.

Etymology: —The specific epithet “cretaceum ” is derived from the habitat of this newly identified species, which thrives on moist, chalky soil slopes.

Vernacular name: —H垩※叶ffẍ (bai e liu ye er jue)

Additional specimens checked:— Polystichum cretaceum (paratype): CHINA. Guangxi: Baise City, Napo County, 105°51′22.174″E, 22°57′30.171″N, elev. ca. 1032m, 15 May 2023, Xu Yi-Da 22251 ( NOCC).

Polystichum fraxinellum : CHINA. Guizhou: 24 Oct 1898, Bodinier, E. M. & Laborde, J. 2527 ( E) E00429039 ; Luodian, elev. 937.3 m, 106°45′44.74″E, 25°33′0.14″N, 14 Oct 2015, Wang M. C. LDX098 ( GZTM) GYBG0005447 ; Zheng'an, Hexi, Shuanglong, 107°22′04″E, 2°26′30″N, elev. 1002.9 m, 25 March2016, Zheng J. H.520324160325014 LY ( GZTM) GZTM0043075 . Sichuan: Leshan, Mt. Emei, elev. 1400 m, 1 Nov 1964, Guan K. J., Wang J. W. & Li C. L., 2422 ( PE) 00984615. Chongqing: Nanchuan, Mt. Jinfoshan , elev. 1100 m, 17 Oct 2002, Zhang X. C., Liu Z. Y. 2596 ( PE) 01450701 .

Polystichum minimum : CHINA. Guizhou: Ninggu, in fissuris rupium, 29 Aug 1965, P. S. Wang 1155 ( PE) 00984641 ; Huaxi Park, elev. 1300 m, Cao Z. Y. 0280 ( PE) 09984639. Chongqing: Wulong, Changba , elev. 540 m, 21 Sept 2007, Liu Z. Y. 180174 ( PE) 01818962 ; Nanchuan, Mt. Jinfoshan , 1 Nov 2002, Lu J. M, Chen Y. & Li H. Z. 047 ( KUN) 1225643 ; 29 Sept 2007, Liu Z. Y. 071510 ( IMC) IMC0006088 . Guangxi: longlin, elev. 1550 m, 105°14′03.72″E, 24°38′37.44″N, 28 Oct 2014, Lv H. Z., Nong D.X. & Cen H. F. 451031141028033 LY ( GZTM) GXMG0188418 .

Polystichum tenuius : CHINA. Guangxi: elev. 1133 m, 2 Aug 1928, Ching R. C. 6649 ( PE) 00984597 ; Nandan, elev. 616 m, 107°36′03.01″E, 25°04′33.28″N, 1 July 2019, Nandan Census Team 451221190701001 LY ( GZTM) GXMG0198694 . Guizhou: Maolan National Nature Reserve , elev. ca. 800 m, 20 Aug 2015, Li Z. Y., Wei R. & Zhang H. R. 7326 ( PE) 02056173. Hunan: Changde, Shimen, Anxi, 110°41′34″E, 29°50′'30″ N, 31 Oct 2013, Jin S. L. & Zhang J. B. ISL-WLSQ202 ( CSH) CSH0141140 ; Sangzhi , elev. 420, 110°04′54″E, 29°42′35″N, 21 Oct 2014, Zhou X. L., Yan Y. H. & Jin D. M. ZXL9690 ( CSH) CSH0045120 .

Figures

FIGURE 2. Morphology and habitat of Polystichum cretaceum Xiaohua Chen & Y.F.Gu. A habitat; B lamina, simple to 1-pinnate; C base of stipe; D pinnated venation; E erect or ascending rhizome; F Sori terminal on veinlets; G scale on lamina abaxially; H hairy on lamina adaxially; I hairy on lamina adaxially under microscope; J scale of petiole base; K spore in distal pole; L spore in proximal pole. Photographs A from the type locality; the others from holotype YYH19982.

FIGURE 3. Polystichum cretaceum Xiaohua Chen & Y.F.Gu. A Habit; B lamima (abaxial view); C 1-pinnated lamima; D lamima with one-lobe at base; E scales at the petiole base; F spore with fenestrate perispore (left side) and smooth spore after removing the perispore (right side). Drawn by Chen Li-Jun from holotype YYH19982.