Microlepia thailandensis S.J. Moore, 2017

Wang, Jenn-Che, Chang, Yi-Han, Chiou, Wen-Liang & Liu, Ho-Yih, 2017, Two new species of Microlepia (Dennstaedtiaceae, Polypodiopsida) from Thailand, Phytotaxa 324 (2), pp. 193-197 : 195

Microlepia thailandensis S.J. Moore , sp. nov. ( Fig. 2 )

Type: — THAILAND. Prachinburi: Kao Yai National Park, Kao Kieo, 16 February 1966, E. Hennipman 3925 (holotype B!, isotypes BM! KYO, L! UC! US!).

Plants 30–45 cm high. Rhizomes long-creeping, 2.5–3.5 mm in diameter, densely covered with hairs; hairs yellow-brown, 2.5–4 mm long, 8–14 cells, capitate. Stipes 1–3 cm apart, 15–20 cm long, brown, shallowly grooved on adaxial surface, hairy throughout; hairs similar to those on rhizome, longer and denser proximally, shorter and sparser distally. Laminae oblong-lanceolate to oblong-triangular, 25–38 cm long and 18–27 cm wide, acuminate at apex, truncate or widely cuneate at base, 1-pinnate-pinnatifid to bipinnate proximally, pinnate distally; rachises brown, grooved on adaxial surface, hairy throughout, hairs of two different length ranges (0.8–1.3 and 2–3.2 mm) mixing together, yellow-brown to brown; pinnae 10–15 pairs, proximally 1-pinnate or deeply pinnatifid, distally simple or shallowly lobed, and gradually reduced in size to form a pinnatifid apex, larger pinnae straight or slightly falcate, more or less ascending, linear-lanceolate, acuminate at apex, truncate or unequally cuneate at base, sessile or shortly stalked (<0.5 cm); costae grooved and brown on adaxial surface, stramineous on abaxial surface, hairy on both surfaces with two different lengths of hairs (0.8–1 and 1.5–2.2 mm); pinnules or segments of proximal pinnae elliptic, oblong to spathulate, acute at apex, margin obscurely crenate, 0.6–1.2 cm long and 0.3–0.6 cm broad, papyraceous, glabrous except on veins; veins in pinnules or segments pinnate, veinlets mainly simple, rarely forked, ending at a hydathode, moderately hairy on abaxial surface, very sparsely on adaxial surface. Sori submarginal, terminal on veinlets, raised on adaxial laminal surface, 1–1.5 mm inside the margin; indusia cup-shaped, hairy.

Distribution and habitat: —Known only from the type locality in Thailand, where it is terrestrial under evergreen, mountain forests at 1000–1200 m elev.

Etymology: —The epithet of this new species indicates it is endemic to Thailand.

Notes: — Microlepia thailandensis is similar to M. kerrii , but differs in the middle pinnae being deeply pinnatifid (vs. simple or shallowly lobed), hairs in two different length ranges mixing on rachises and costae (vs. hairs being almost the same length), lamina narrowing gradually towards apex (vs. lamina somewhat abruptly narrowing near apex), and hairy indusia (vs. glabrous indusia). Microlepia thailandensis is also similar to M. intramarginalis ( Tagawa 1941: 202) Serizawa (1972: 48) , and Fraser-Jenkins et al. (2015) considered them the same species. However, we find that M. thailandensis differs from M. intramarginalis in the pinnae being mainly deeply pinnatifid, even though there are sometimes a few free basal lobes in the proximal half of the lamina (vs. distinctly bipinnate) and hairs on rachises and costae more plentiful and longer (vs. much less hairy and hairs shorter). In some cases, M. thailandensis is somewhat similar to M. marginata (Panzer) C. Chr. and M. calvescens (Wall. ex Hook.) C. Presl. Microlepia thailandensis differs from the former in the pinnae mainly being deeply pinnatifid (vs. simple pinnae with crenate margins, or moderately pinnatifid at most), and fronds less hairy (vs. usually very hairy). Microlepia thailandensis differs from M. calvescens in the lamina narrowing gradually towards the apex (vs. lamina usually narrowing abruptly near apex), fronds somewhat hairy (vs. glabrous or nearly so), the basal lobes of pinnae of the proximal laminae being usually reduced (vs. not reduced or even larger), and indusia hairy (vs. glabrous or nearly so).

Figures

FIGURE 2. Photograph of the holotype of Microlepia thailandensis (E. Hennipman 3925, B_20_0157478).