Hymenasplenium obtusidentatum Y.Fen Chang & G.Cheng Zhang, 2022

Chang, Yanfen, Zhang, Guocheng, Wang, Zhixin & Cao, Limin, 2022, Molecular and morphological evidence reveals a new fern species of Hymenasplenium (Aspleniaceae) from south and southwestern China, PhytoKeys 211, pp. 93-106 : 93

publication ID

https://dx.doi.org/10.3897/phytokeys.211.90363

persistent identifier

https://treatment.plazi.org/id/0971BC2A-F87F-5E5F-958C-66D3A50BB0C8

treatment provided by

PhytoKeys by Pensoft

scientific name

Hymenasplenium obtusidentatum Y.Fen Chang & G.Cheng Zhang
status

sp. nov.

Hymenasplenium obtusidentatum Y.Fen Chang & G.Cheng Zhang sp. nov.

Type.

China. Yunnan Province, Xishuangbanna, Menghai: Chang1258. 2019. (holotype, HITBC; isotype, KUN) (Figs 2 View Figure 2 , 3 View Figure 3 ) .

Description.

Plants 25-40 cm tall. Rhizomes long creeping, 2-4 mm in diameter, apex scaly; scales brown, lanceolate to triangular, entire. Fronds remote, up to 6 mm apart, grayish green when dry, herbaceous; stipe reddish brown to dark brown, 10-20 cm long, base ca. 1-1.5 mm in diam., subglabrous, base with sparse scales similar to those on rhizome; lamina one-pinnate, narrowly triangular to triangular, 15-30 × 8-15 cm, base truncate and reduced, apex acuminate to caudate; rachis reddish brown to dark brown, subglabrous; pinnae 15-21 pairs, trapeziform to falcate, basal pinnae nearly opposite, middle pinnae 3.5-8 × 1-1.8 cm, dimidiate, apex obtuse to acute, base asymmetrical, acroscopic side truncate and often almost parallel to rachis, basiscopic side of basal pinnae excavate, in middle pinnae narrowly cuneate and entire, acroscopic margin serrate, teeth blunt or rounded; pinnae spreading to ascending. Veins forking and terminating in marginal teeth, basiscopic side with 4-6 veins lacking. Sori inframedial to medial, linear, 3-5 mm, indusia persistent, pale brown, membranous, entire, opening toward the costa. Spores elliptic to reniform, perispore fimbriate-alate, 38-43 μm in diam.; 64 spores per sporangium.

Diagnosis.

Hymenasplenium obtusidentatum is similar to H. excisum . However, H. obtusidentatum has a thinner rhizome and stipe, not shiny and reddish brown to dark brown stipe and rachis, blunt or rounded pinna marginal teeth, and truncate lamina base.

Distribution and habitat.

Hymenasplenium obtusidentatum is currently known to coexist with H. excisum in south and southwestern China, and adjacent areas. It occurs in soil or on rocks near streams in half-shaded forests at alt. 1000-1500 m.

Additional specimens examined.

China. Yunnan Province, Menghai County, 2019; Chang1256, Chang1260; Chang1261, Chang1262; Chang1339 (HITBC); Pu’er City, Pu’er Sun River National Forest Park , 2018; Xu 324 (SYS) . Hainan Province, Ledong County, 2019; Chang1284, Chang1285; Chang1286 (HITBC) .