Asplenium jiulianshanense K.W.Xu & G.L.Xu, 2022

Lin, Chen-Xue, Xu, Guo-Liang, Jin, Zhi-Fang, Liao, Wen-Bo & Xu, Ke-Wang, 2022, Molecular, chromosomal, and morphological evidence reveals a new allotetraploid fern species of Asplenium (Aspleniaceae) from southern Jiangxi, China, PhytoKeys 199, pp. 113-127 : 113

Asplenium jiulianshanense K.W.Xu & G.L.Xu sp. nov.

Figs 1 , 2 , 5

Diagnosis.

Asplenium jiulianshanense somewhat resembles A. kiangsuense by its small size, rachises adaxially without a deep furrow, pinnae elliptic to trapeziform-oblong, sori 3-4 per pinna in the middle part of frond. However, the former has rachises with only one gemma near apex, pinnae (15-)20-35 pairs, pinna margins entire to sparsely crenate, exospore length 37-43 μm, while the latter has rachises without gemmae near the apex, pinnae 8-20(-22) pairs, pinna margins entire to sinuate, exospore length 31-36 μm.

Type.

China. Jiangxi province, Ganzhou City, Jiulianshan National Nature Reserve , 256 m, 24°56'2.04"N, 114°49'23.44"E, 8 Jun 2021, Guo-Liang Xu & Ke-Wang Xu XKW681 (holotype, NF!; isotype, SYS!) .

Description.

Plants 8-15 cm tall. Rhizome erect, short, apex densely scaly; scales narrowly triangular to linear-subulate, purplish-black, 2-3 × 0.4-0.6 mm. Fronds caespitose; stipe castaneous-brown to purplish-black, shiny, terete, 1-3 cm, glabrous; lamina linear, 8-12 × ca. 1.2 cm, apex acute, 1-pinnate; pinnae (15-)20-35 pairs, lower ones subopposite, hardly reduced, middle pinnae spreading horizontally or slightly reflexed, elliptic to trapeziform-oblong, 3-6 × 3-5 mm, base asymmetrical, acroscopic side truncate and close to rachis, basiscopic side narrowly cuneate, shortly stalked to subsessile, margin entire to sparsely crenate, apex obtuse. Venation anadromously pinnate or with first basiscopic vein lacking, costa with 2 or 3 acroscopic veins, obscure, veins simple or 1-forked. Fronds papery, grayish-green when dry; rachis castaneous-brown to purplish-black, shiny, glabrous, semiterete, and adaxially flat or with 2 slightly raised lateral ridges, often gemmiferous near the apex. Sori (1-)3-4(-6) per pinna, linear-elliptic, ca. 1 mm in length, median on subtending vein; indusia grayish-green, elliptic, membranous, entire, and opening toward costa. Spores with lophate perispore, average exospore length 37-43 µm.

Etymology.

Based on the Chinese pinyin, Jiulianshan, the name of the National Nature Reserve in southern Jiangxi, China, referring to the type locality of the species.

Vernacular name.

九连山铁角蕨 ( jiǔ-lián-shān tiě-jiǎo-jué).

Geographical distribution and habit.

Asplenium jiulianshanense is known only from a single locality in Mount Jiulianshan, Jiangxi, China, where there have been multiple collections. It was observed to grow on cliff rocks under shrubs at an elevation of ca. 200 m in subtropical evergreen broad-leaved forest.

Conservation.

We provisionally assess A. jiulianshanense as Endangered based on criterion D of IUCN (2012). Only one population of the new species was found at type locality with no more than 250 mature individuals.

Cytology.

The chromosome number of A. jiulianshanense is 2n = 144 (Fig. 6 ). The chromosome number of A. jiulianshanense indicates that the new species is a tetraploid species.

Additional specimens examined.

China. Jiangxi province, Ganzhou City, Jiulianshan National Nature Reserve , 256 m, 24°56'2.04"N, 114°49'23.44"E, 10 Jul 2021, Guo-Liang Xu & Ke-Wang Xu XKW685 (NF!); the same collection information, Guo-Liang Xu & Ke-Wang Xu XKW686 (NF!) .

Figures

Figure 1. Asplenium jiulianshanense K. W. Xu & G. L. Xu A, B habitat where the new species was discovered C habit D rhizome and roots E irregular branch of lamina F adaxial view of portion of lamina G abaxial view of portion of fertile lamina H frond with a gemma at the distal end of the rachis.

Figure 2. Asplenium jiulianshanense K. W. Xu & G. L. Xu A habit B pinna showing the venation and the distribution of sori C rhizome scale. Scale bars: 2 cm (A); 5 mm (B); 2 mm (C).

Figure 5. Asplenium jiulianshanense K. W. Xu & G. L. Xu A-C spore morphology of the new species D rhizome scale. Scale bars: 300 μm (A); 10 μm (B, C); 1 mm (D).

Figure 6. Chromosomes of Asplenium jiulianshanense K. W. Xu & G. L. Xu in mitotic root-tip cells, 2 n = 144. Scale bars: 20 μm.