Pteridrys costularis Li Bing Zhang, Liang Zhang, N. T. Lu & X. M. Zhou 2017, sp. nov.
Creators: name: Zhang, Liang
name: Lu, Ngan Thi
name: Zhou, Xin-Mao
name: Zhang, Li-Bing
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Polypodiopsida
Polypodiales
Tectariaceae
Pteridrys
Pteridrys costularis

description: Pteridrys costularis Li Bing Zhang, Liang Zhang, N.T.Lu & X.M.Zhou, sp. nov. Figs. 1A ‒ D & 2.
Type:— VIETNAM. Bac Kan: Na Phac District, elev. 1100–1300 m, 6 December 2013, Li Bing Zhang, Liang Zhang & Ngan Thi Lu 6731 (holotype VNMN!, isotypes CDBI!, MO!).
Diagnosis:—This species is similar to Pteridrys microthecia (Fée 1865: 37) C. Christensen & Ching (1934: 139) in having basal basiscopic lobes of basal pinnae elongate and strongly toothed, and lobes oblong and serrulate only on distal margins, but differs in basal basiscopic veinlet of each lobe (arising from the base of costule vs. obviously arising from costae), and the lowest secondary veinlets of primary veinlets (arising from primary veinlets and distant from costule vs. arising from costule).
Plants ca. 0.7 m tall. Rhizome ascending. Stipe stramineous, more than 25 cm long, rhizome apex and stipe base covered with lanceolate scales. Lamina papery, brown when dry, ca. 45 × 23 cm, oblong to oblong-lanceolate, bipinnatifid; rachis stramineous, glabrous; lateral pinnae ca. 20 pairs; basal pinnae lanceolate, ca. 15 × 7 cm, petiolules ca. 0.4 cm, lobed (sinuses more than 2/3 the length of the adjacent lobes); basal basiscopic lobes of basal pinnae lanceolate, elongate, ca. 3.5 × 1.0 cm, margins strongly dentate to slightly pinnatilobate, teeth or lobes ca. 12 pairs; basal acroscopic lobes similar to next one, slightly overlapping rachis on abaxial side; pinna lobes 16–18 pairs, 1.7–2.4 × 0.7–0.9 cm, oblong, acute at apex, serrulate on the distal 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 5–8 pairs on each lobe, 1–2(–3)-furcate; soriferous veinlets stopping at sori; basal basiscopic veinlet of each lobe arising from base of costule; lowest secondary veinlets of primary veinlets arising from primary veinlets and distant from costule. Sori terminal on veinlets, 3–5 pairs on each lobe; indusia brown, 0.5 ‒ 0.6 mm in diam., rounded-reniform, without hairs, fugacious.
Etymology:— From the Latin costularis, of or pertaining to a costule, referring to the basal basiscopic veinlet of each lobe arising from the base of a costule in this species (instead of a costa).
Distribution:— This species is currently known to be endemic to northern Vietnam.
Notes:— This species is also similar to Pteridrys lofouensis (Christ 1910: 143) C. Christensen & Ching (1934: 134) in having basal basiscopic lobes of basal pinnae elongate and lobes oblong, but the new species has a smaller habit (ca. 0.7 m tall), and basal basiscopic lobes of basal pinnae slightly elongate (ca. 3.5 cm) and strongly toothed on margins, while P. lofouensis has a larger habit (0.8 ‒ 1.3 m long), and basal basiscopic lobes strongly elongate (7 ‒ 10 cm long) and pinnatifid.
description: Published as part of Zhang, Liang, Lu, Ngan Thi, Zhou, Xin-Mao & Zhang, Li-Bing, 2017, Three new species of the fern genus Pteridrys (Tectariaceae) from Vietnam, pp. 279-287 in Phytotaxa 324 (3) on pages 279-282, DOI: 10.11646/phytotaxa.324.3.4, http://zenodo.org/record/13698346