Pteridrys hanoiensis 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 : 282

Pteridrys hanoiensis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou , sp. nov. Fig. 3

Type:— VIETNAM. Hanoi: Ba Vi National Park, elev. ca. 900 m, 25 November 2013, Li Bing Zhang, Liang Zhang & Ngan Thi Lu 6517 (holotype VNMN!, isotypes CDBI!, MO!).

Diagnosis:—This species is similar to Pteridrys lofouensis (Christ) C.Chr. & Ching in having basal basiscopic lobes of basal pinnae elongate, lobes oblong and rounded at apex, and the lowest secondary veinlets of primary veinlets arising from primary veinlets, but differs in basal acroscopic lobes (usually overlapping the rachis vs. not overlapping the rachis), lobes (1.5–2.5 cm long vs. 1.3–1.7 cm long), and sori (7 ‒ 8(–10) pairs on each lobe and subterminal on veinlets vs. sori 4 ‒ 6(‒ 7) pairs on each lobe and often terminal on veinlets).

Plants more than 1.3 m tall. Rhizome not seen. Stipe stramineous, 60 ‒ 70 cm long, scales not seen. Lamina thinly papery, dark brown when dry, 70 ‒ 100 × 35 ‒ 45 cm; oblong to oblong-lanceolate, bipinnatifid; rachis brown when dry, glabrous; lateral pinnae ca. 25 pairs; basal pinnae lanceolate, 20 ‒ 25 × 10 ‒ 12 cm, petiolules ca. 0.5 cm, deeply lobed (sinuses nearly reaching the costae); basal basiscopic lobes of basal pinnae lanceolate, strongly elongate, 9 ‒ 10 × 2.5 ‒ 3 cm, pinnatifid, lobes ca. 15 pairs, margins subentire to serrate at apex; basal acroscopic lobes similar to next one, overlapping rachis on abaxial side; pinna lobes 21–25 pairs, 1.3 ‒ 2 × 0.6–0.7 cm, oblong, obtuse at apex, serrate to entire on margins, involute when dry, sinuses between lobes 0.1 ‒ 0.2 cm, with a sharp tooth in each sinus; costae glabrous; veins free, slightly distinct on both surfaces, veinlets 7–10 pairs on each lobe, 2(–3)-furcate; soriferous veinlets stopping at sori or going through sori but not reaching lobe margins; basal basiscopic veinlets of each lobe arising from base of costule or from costa and slightly remote from base of costule; lowest secondary veinlets of primary veinlets arising from costule. Sori terminal or subterminal on veinlets, 7 ‒ 8(‒ 9) pairs on each lobe; indusia brown, 0.5 ‒ 0.7 mm in diam., rounded-reniform, without hairs, persistent.

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

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

Notes:— Phylogenetically, this species is sister to a clade containing Pteridrys costulalis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou , P. lofouensis (Christ) C.Chr. & Ching , P. vietnamensis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou (see below), and an undescribed species.

Figures

FIGURE 3. Pteridrys hanoiensis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou.—A. Lower portion of frond.—B. Portion of pinna.