Hymenasplenium speluncicola Li Bing Zhang, K.W. Xu & H.He, 2018

Xu, Ke-Wang, Zhang, Liang, Lu, Ngan Thi, Zhou, Xin-Mao, He, Hai, Luong, Thien Tam, Knapp, Ralf, Liao, Wen-Bo & Zhang, Li-Bing, 2018, Nine new species of Hymenasplenium (Aspleniaceae) from Asia, Phytotaxa 358 (1), pp. 1-25 : 20-21

Hymenasplenium speluncicola Li Bing Zhang, K.W. Xu & H.He , sp. nov. Fig. 14 .

Type:— CHINA. Guangxi: Jingxi, Wuping Xiang, Wuping Street, Gongtong Big Cave , 23°11’52.97”N, 106°28’09.88”E, elev. 700–800 m, 31 October 2010, Li Bing Zhang, Hai He & Yu Wang 5494 (holotype CDBI! , isotypes CTC! , MO! ).

Diagnosis:— Hymenasplenium speluncicola is morphologically similar to H. hondoense in having teeth at base of pinnae slightly retuse and sori medial, but the former has rhizomes densely covered with long yellowish brown woolly indumentum, petioles slender (ca. 1 mm in diam.), pinnae falcate or lanceolate and acuminate, while the latter has rhizomes densely covered with long yellow brown woolly indumentum, petioles thick (ca. 1.5 mm in diam.), pinnae trapeziform to falcate and subacute to obtuse at apex.

Plants perennial, evergreen, 20–40 cm tall. Rhizomes long creeping, ca. 2 mm in diam., apex scaly, scales dark brown, narrowly triangular or lanceolate, margins nearly entire, 0.2–0.4 × 0.8–1.5 mm; root yellowish brown when dried, slender, up to 6 cm long, ca. 0.2 mm diam, rhizome and root densely covered with long yellow brown woolly indument. Fronds remote, 10–20 mm apart, herbaceous; petioles slender, shiny, dark brown, glabrous, 15–25 cm long, ca. 1 mm in diam. Laminae narrowly ovate, 1-pinnate, 15–20 × 3.5–7 cm, base reduced, widest near base, gradually narrowing toward apex, apex acuminate; rachises 0.5 mm in diam., glabrous, shiny, dark brown, adaxial side grooved and with 2 green narrow wings. Pinnae shortly stalked to almost sessile at apex, 12–25 pairs, base nearly opposite, middle and apex alternate, falcate or lanceolate, (middle pairs) 2–4 × 0.4–0.6 cm, about 2–3(–5) mm apart, base asymmetrical, acroscopic side truncate and subparallel or forming an angle less than 15° with rachis, basiscopic side cuneate, with 10–15 mm absent (calculated from the base to the first tooth appearing in the margin of basiscopic side), acroscopic margins serrate, teeth small and dense, usually slightly retuse at the basal portion of pinnae, basiscopic margins entire at base, serrate in the middle and apex; pinna apex acuminate. Veins visible on both sides of pinnae, stramineous, often brown near pinnae petioles, lateral veins visible on both sides of pinnae, green, forking and terminating in marginal teeth or below notches, 2–3 basal basiscopic veins lacking. Sori linear, 1–2 mm long, medial, 3–5(–6) on acroscopic side and (1–)2–4 on distal basiscopic side of the pinnae in the middle part of the laminae, centers 1–2(–5) mm apart from one another; indusia brown, linear, membranous, entire, opening toward costa.

Geographical distribution:— Hymenasplenium speluncicola is currently known from southeastern Guangxi and southern Guizhou, China.

Ecology:— Hymenasplenium speluncicola was observed to grow on rocks or soil at the entrance of limestone caves.

Etymology:—The species epithet is based on the Latin noun, spelunca, cave, and the Latin suffix, -cola, dweller, referring to the cave-dwelling habitat of the species.

Vernacular name:— AEḰůďäffǎ (dong xue mo ye tie jiao jue).

Taxonomic notes:—Morphologically, Hymenasplenium speluncicola is very special. It has rhizomes densely covered with long yellow brown woolly indumentum, petioles slender, fronds thin herbaceous, pinnae narrow, and pinna apex acuminate. It is likely that H. speluncicola only grows in limestone areas of Guangxi and Guizhou, southern China.

Hymenasplenium speluncicola is another species in the genus discovered from limestone caves after H. hastifolium K.W. Xu, Li Bing Zhang & W.B.Liao (2018b: 281) . Similar cave endemics are common in some other fern genera such as Polystichum Roth (1800: 31 ; Dryopteridaceae ; e.g., Han et al. 2016).

Additional material examined: — CHINA. Guizhou: Luodian, Limu Xiang, La’ang Cun, Gaopo Zu, Gaopo Big Cave , 25°38’03.40”N, 106°43’00.95”E, elev. 1000 m, 7 November 2011, Li Bing Zhang, Hai He & Yu Wang 6035 (CDBI!, CTC!) .

Figures

FIGURE 14. Hymenasplenium speluncicola Li Bing Zhang, K.W. Xu & H.He.—A. Habit.—B. Portion of abaxial lamina.—C. Portion of adaxial lamina.