Tectaria danangensis S.Y. Dong, 2022

Pham, Van The, Li, Shu-Han & Dong, Shi-Yong, 2022, Tectaria danangensis (Tectariaceae), a new fern species from Vietnam, PhytoKeys 194, pp. 1-13 : 1

Tectaria danangensis S.Y. Dong sp. nov.

Figs 1A, B , 2

Type.

Vietnam. On the border between Da Nang and Thua Thien Hue Prov.: Bach Ma National Park , 107°51'37"E, 16°17'59"N, 680 m elev., 02 Dec 2017, S.Y. Dong 4909 (holotype: IBSC!, designated here; isotypes: HNU!, IBSC!) .

Diagnosis.

Tectaria danangensis is similar to T. poilanei Tardieu, but differs in its irregularly 2-rowed sori (versus regularly 2-rowed, well-spaced and evenly arranged) between lateral veins, fronds more or less being dimorphic (versus monomorphic) and basal pinnae each having a base-joined (versus free) lobe.

Description.

Rhizome short, erect or decumbent. Fronds more or less dimorphic, with fertile fronds slightly contracted; stipe reddish-brown, 3-4 mm in diameter, 30-50 cm long, bearing scales only at base; scales lanceolate, ca. 8-10 × 1-1.5 mm, reddish-brown; lamina nearly round or oblong, 35-55 × 25-35 cm, imparipinnate or terminated by tri-lobed segments, having 2-4(6) pairs of lateral pinnae, pinnae and segments entire at margin, herbaceous in texture, hairless; basal pinnae forked, 14-27(33) × 1.7-5 cm, petiolules 0-5 mm long, acroscopic base cuneate, basiscopic base round, apex caudate-acuminate, having a basiscopic lobe, the basiscopic lobes 7-24 × 1-3.5 cm; suprabasal pinnae linear, 14-30 × 1-4.5 cm, sessile, base cuneate, apex acuminate or caudate; upper pinnae similar to suprabasal pinnae in size and shape, but mostly adnate to rachis. Veins fully anastomosing, with most areoles having included free or forked veinlets, transverse veins between lateral veins mostly indistinct. Sori round, borne on anastomosing veins, generally in two rows between lateral veins of pinnae (more or less with additional sori present beyond two rows), 8-11 each row in broad pinnae or 4-6 in obviously contracted fertile pinnae, well-spaced or adjacent. Indusia round-reniform, mostly curled and almost covered by sporangia when mature.

Distribution and habitat.

Vietnam (Da Nang, Lam Dong, Quang Binh, Quang Nam, Quang Tri, Thanh Hoa, and Thua Thien Hue); terrestrial in broadleaved evergreen forest, occurring in slopes of valley or along mountain ridge, elev. 200-1400 m, locally common.

Additional specimens examined

(paratypes).

Vietnam. Da Nang: Ba Na Mountain, Hoa Vang District, Sallet s.n. (P); without locality, Gaudichaud s.n. (P). Lam Dong: Da Lat, Wu et al. WP1447 (HN). Quang Binh: Phong Nha - Ke Bang National Park , Nguyen NT 39, NT69 & NT102 (HNU); without locality, Phan s.n. (HNU). Quang Nam: without locality, Poilane 29484 & 31661 (P). Quang Tri: Huong Hoa District, Averyanov et al. CPC2906 & CPC2907 (HNU); Dakrong District , Phan et al. HLF6122 (HNU); Dakrong Nature Reserve , Lu 19232 (TAIF); “Mai-lanh”, Poilane 1189 (P, PE, SING). Thanh Hoa: Phu luc, Lecomte & Finet 1338 (P). Thua Thien Hue: A Luoi District , Averyanov et al. HAL7289, HAL7342, HAL7423, HAL7622, HAL7738 (HNU); Nam Dong District, Averyanov et al. HAL6940 (HNU); "Tua Luu", Cadiere 165 (P). Southern Vietnam (Annam, with localities’ names unreadable): Eberhardt 373 (P).

Figures

Figure 1. Morphological comparison between Tectaria danangensis (A, B) and T. poilanei (C, D) A, C habit B, D detail of a pinna showing venation and sori arrangement. Drawn by Shu-Han Li, with A and B based on Dong 4909 (holotype, IBSC) and C and D on Poilane 24074 (holotype, P).

Figure 2. Herbarium specimens of Tectaria danangensis, showing contracted fertile fronds (A, C) as compared with sterile fronds (B, D) A, B Dong 4909 (type, IBSC) C, D Cadiere 165 (P).