Hypodematium eglandulosum X.P.Fan, Liang Zhang & Li Bing Zhang, 2021

Fan, Xue-Ping, Lu, Ngan Thi, Zhang, Liang & Zhang, Li-Bing, 2021, Hypodematium chrysolepis comb. nov. from Africa and H. eglandulosum sp. nov. from Asia (Hypodematiaceae), Phytotaxa 524 (2), pp. 99-106 : 100-103

Hypodematium eglandulosum X.P.Fan, Liang Zhang & Li Bing Zhang , sp. nov. ( Figs. 1 , 2 ).

Type:— CHINA. Guizhou: Zhijin County, Niuchang Town , Heba Village , on the limestone wall of a cave, 26°37’ N, 106°02’ E, 20 August 2017, Li-Bing Zhang, Yi-Fan Duan & M. Kropf 9661 (holotype CDBI!) .

Diagnosis:— Hypodematium eglandulosum is most similar to H. squamuloso-pilosum Ching (1977: 465) in small stature, having laminae usually 3-pinnatifid, densely covered with long acicular grayish white hairs, and lobes oblong and with obtuse apices, but the former has fronds only covered with long acicular hairs and stipes sparsely covered with acicular hairs, while the latter has fronds mixed with acicular and glandular hairs, and stipes densely covered with acicular and glandular hairs.

Description:—Plants mostly small, 6–35 cm tall, lithophytic, yellowish green when dry. Rhizomes short creeping, swollen stipe bases covered with scales densely; scales reddish brown, lustrous, lanceolate, 1.5–2 cm × 1–1.5 mm, membranaceous, apex acuminate, margin dentate. Leaves distant; stipe stramineous, lustrous, usually slender, 2.5–16 cm long, 0.4–0.9 mm in diam., upward usually covered with sparsely hairs or glabrous occasionally, generally shorter than rachis; laminae deltoid-ovate, base cordate, 4–20 × 3–18 cm, base tripinnate, bipinnate upward, apex acuminate and pinnatifid; pinnae 5–8 pairs, alternate, flat or slightly oblique, basal pair largest, deltoid-ovate, base cordate, 1.5–10 × 1–6 cm, 0.1–1 cm stalked, 2-pinnate, apex acuminate; pinnules 4–6 pairs, anadromous, alternate, slightly oblique, acroscopic ones smaller, proximal basiscopic pair largest, triangular-lanceolate, shortly stalked, base cuneate or truncate, 1-pinnate, apex acuminate; secondary pinnules oblong, sessile, base cuneate, connected to each other by narrow wings, 4–6-lobed; lobes oblong, each lobe nearly entire or slightly wavy at apex, apex obtuse. Laminae chartaceous, densely covered with long acicular grayish white hairs, 0.5–0.8 mm long, about 25+ hairs/mm², margins covered with many long acicular hairs, 0.5–0.8 mm long; rachises and pinna rachises densely covered with grayish white hairs on both surfaces. Veins obvious on both surfaces, pinnate, free, reaching at margin. Sori orbicular, dorsal, medium-sized, 0.7–1.1 mm in diam., 1–3 per lobe, inframedial of veinlets, usually confluent when mature. Indusia persistent, grayish, reniform to rounded, densely covered with long gray acicular hairs, usually smaller than sori when mature. 32 spores per sporangium.

Distribution & habitat:— Hypodematium eglandulosum is distributed in southern China (Guizhou, Guangxi) and Southeast Asia ( Laos and Vietnam). It is not found in high elevations. It can occur inside or outside caves and grows in limestone crevices at elevations of 200–1000 m.

Etymology:—From the Latin adjective, eglandulosum , without glandular hairs, referring to its plant densely covered with acicular hairs without any glandular hairs.

Taxonomic notes:—Morphologically, Hypodematium eglandulosum is characterized by plants small, leaves distant and laminae 3-pinnatifid, stipes upward sparsely covered with acicular hairs, laminae and rachises densely covered with long acicular hairs, and lobes nearly entire. Hypodematium eglandulosum is distantly related with H. squamulosopilosum , though they are very similar to each other in morphology. Hypodematium eglandulosum is closely related with H. shingii Li Bing Zhang, X.P.Fan & X.F.Gao in Fan et al. (2021: 88). Our unpublished data show that H. eglandulosum constitutes a unique major clade of its own (Fan et al. submitted). In addition, H. squamuloso-pilosum , with its type being from Wuhan, occurs in central and eastern China and South Korea, whereas H. eglandulosum is distributed in southern China and Southeast Asia. The comparison of H. eglandulosum with similar species is listed in Table 1 .

Additional specimens examined:— CHINA. Guangxi: Jingxi City, Dizhou town , on the limestone wall of the cave, elev. 715 m, 28 January 2019, She-Lang Jin 6762 (CDBI!) . Guizhou: Changshun County, Weiyuan town , on the limestone wall of the cave, 26°01’ N, 106°30’ E, elev. 1000 m, 29 October 2011, Li-Bing Zhang, Hai He & Yu Wang 5898 (CDBI!) . LAOS. Gnommalat District : Khammouane Province, Tnathote Village , epiphyte on the limestone rock, elev. 200–350 m, 27 October 2007, Su-Gong Wu et al. WS-003 (KUN!) . VIETNAM. Bac Kan: Na Ri, Kim Hy Com., Kim Hy NR., Ke Village , elev. 500 m, 4 December 2013, Li-Bing Zhang, Liang Zhang & Lu Thi Ngan 6706 (CDBI!) . Ha Giang: Vi Xuyen District, Tung Ba Community, Hong Minh Village , Khau Ca Nature Reserve , elev. 200 m, 12 December 2013, Li-Bing Zhang, Liang Zhang & Lu Thi Ngan 6924 (CDBI!) . Ha Giang: Vi Xuyen District, Tung Ba Community, Hong Minh Village , Khau Ca Nature Reserve , elev. 200 m, 12 December 2013, Li-Bing Zhang, Liang Zhang & Lu Thi Ngan 6920 (CDBI!) . Hoa Binh: Tan Lac District, Tam Son Community, Ngoc Son Ngo Luong Nature Reserve , Ho Duoi Village , elev. 750 m, 22 November 2013, Li-Bing Zhang, Liang Zhang & Lu Thi Ngan 6388 (CDBI!) .

Figures

FIGURE 1. Hypodematium eglandulosum X.P.Fan, Liang Zhang & Li Bing Zhang.—A. Habit.—B, C. Pinnules showing sori.—D. Portion of stipe.—E. Portion of rachis with portion of pinna.—F. Sporangium (based on the holotype).

FIGURE 2. Hypodematium eglandulosum X.P.Fan, Liang Zhang & Li Bing Zhang.—A, E & G. Habit.—B. Portion of adaxial lamina.— C. Portion of abaxial pinna showing sori.—D. Portion of abaxial lamina.—F. Portion of stipe.