Pteridrys vietnamensis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou, 2017

Zhang, Liang, Lu, Ngan Thi, Zhou, Xin-Mao & Zhang, Li-Bing, 2017, Three new species of the fern genus Pteridrys (Tectariaceae) from Vietnam, Phytotaxa 324 (3), pp. 279-287 : 285

publication ID	https://doi.org/ 10.11646/phytotaxa.324.3.4
DOI	https://doi.org/10.5281/zenodo.13698360
persistent identifier	https://treatment.plazi.org/id/5B0B87FA-9A77-FFDD-FF6F-FF018843FC65
treatment provided by	Felipe
scientific name	Pteridrys vietnamensis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou
status	sp. nov.

Treatment

Pteridrys vietnamensis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou View in CoL , sp. nov. Figs. 1E–H View FIGURE 1 & 4 View FIGURE 4 .

Type:— VIETNAM. Phu Tho: Tan Son District, Xuan Son National Park, elev. ca. 950 m, 27 November 2013, Li Bing Zhang, Liang Zhang & Ngan Thi Lu 6554 (holotype VNMN!, isotypes CDBI!, MO!).

Diagnosis:—This species is similar to Pteridrys lofouensis (Christ) C.Chr. & Ching in having the basal basiscopic pinnules of the basal pinnae strongly elongate and crenate-dentate margins on the lobes, but differs in lamina color (dark green when dry vs. dark brown when dry), lobe shape (lanceolate vs. oblong), the origin of the basal basiscopic veinlet in a lobe (usually arising from the base of costule vs. arising from costae) and number of sori (7–11(–18) pairs on each lobe vs. sori 4 ‒ 6(‒ 7) pairs on each lobe).

Plants ca. 1.5 m tall. Rhizome not seen. Stipe stramineous, more than 60 cm long, scales not seen. Lamina thinly papery, dark green when dry, ca. 80 ‒ 100 × 35 ‒ 50 cm, oblong to oblong-lanceolate, bipinnatifid; rachis brown, glabrous; lateral pinnae ca. 25 pairs; basal pinnae lanceolate, ca. 35 × 15 cm, petiolules ca. 0.35 cm, deeply lobed (sinuses nearly reaching the costae); basal basiscopic lobes of basal pinnae broadly lanceolate, strongly elongate, ca. 15 × 4 cm, pinnatifid, lobes ca. 23 pairs, oblong to lanceolate, margins slightly serrate at distal part, apex obtuse or acute; basal acroscopic lobes similar to next one, overlapping rachis; pinna lobes 30–35 pairs, 2.5–5 × 0.5–1.0 cm, lanceolate, acuminate, serrate on margins, sinuses between lobes 0.1 ‒ 0.2 cm, with a sharp tooth in each sinus; costae glabrous; veins free, distinct on both surfaces, veinlets 9–13(–17) pairs on each lobe, 2–3(–4)-furcate; soriferous veinlets stopping at sori or going slightly through sori but not reaching lobe margins; basal basiscopic veinlets of each lobe arising from base of costule; the lowest secondary veinlets of primary veinlets often arising from costule. Sori terminal, subterminal or dorsal on veinlets, 7–11(–18) pairs on each lobe; indusia brown, rounded-reniform ca. 0.5 mm in diam., without hairs, persistent.

Etymology:— From the country name Vietnam and the Latin ending - ensis, of origin, referring to the type locality in Vietnam.

Distribution:— This species is currently known to be endemic to northern Vietnam.

Notes:— This is a very distinct species with lanceolate lobes acuminate at apex, which is reminiscent of Pteridrys cnemidaria ( Christ 1910: 140) C. Christensen & Ching (1934: 136) , but the former has sessile or subsessile pinnae, while the latter has obvious pinna petiolules up to 4 cm long.