Typhonium phuocbinhense V.D.Nguyen & T.Croat, 2021

Nguyen, Van Du, Toan, Le Chi, Nguyen, Van Dinh, Tam, Minh, Thi, Van Anh Nguyen & Croat, Thomas, 2021, Typhonium phuocbinhense sp. nov. (Araceae: Areae), a new species from central Vietnam, Phytotaxa 482 (1), pp. 73-79 : 77-78

Typhonium phuocbinhense V.D.Nguyen & T.Croat sp. nov.

Typhonium phuocbinhense is close to T. varians Hett.& Sookch. By having triolate leaf blade, spathe lamina triangular, staminodes subulate, acute, pale yellow, curved. It is different from later species by having leaf blade not variegated (vs variegated), spathe tube brown outside (vs green), spathe lamina narrow or elongate triangular, 12–16 × 4.0– 4.5 cm (vs triangular, 7–14 × 4.0– 7.5 cm), staminodes folded 180 o (vs just curved down ward not folded).

Type: — VIETNAM. Ninh Thuan Province, Bac Ai District, Phuoc Binh Commune, Phuoc Binh National Park , Gia Nhong streamline, GPS 12 o 00742 N 108 o 74117, June 8, 2017, cultivated in Hanoi, Du, Diep 08 (holotype HN)

Herbal, tuberous plant, 6–34 cm tall. Tuber subcylindrical or irregular cylindrical, 8–15 mm long, 10–15 mm wide, around covered by several lateral shoots, lateral shoots develop to small tubers and go off mother tuber to developing to new plant, outside dirty light brown or dirty light yellow; roots abundant at top of tuber, 7 cm long. Leaves 2–3 together; petiole slender, 6–34 cm long, 1.5–2.0 mm diam., pale to mediate green; leaf blade entire and trilobate; entire blade with pre-lobe ovate or triangular, 2.0–3.0(5.5) cm long, 2.0–2.8(4.5) cm at widest point, base deeply concave, basic lobes elongate shape, obtuse at apex; trilobate blade with anterior lobes sub ovate or lanceolate, 3.0– 7.2 cm long, 1.8–4.5 cm at widest point, base with 2 margins ended early at connecting point with lateral lobes, distant from midrib of lateral lobes 0.8–1.0 cm, apex acute, with short acuminate or without acuminate; lateral lobes usually semi-ovate or semi-triangular or asymmetry triangular, 3–5 cm long, 1.2–2.0 cm wide at base, outside bases round, ended early on midrib; inside bases ended early and connect to outside base of anterior lobe, apex obtuse; veins reticular, obviously at beneath surface, lateral veins 4–5 at lobes, 30–60 o from midrib, midrib of lateral lobes elongate and connect to petiole, outside empty at base, collective vein distant from leaf margin 2–3 mm; leaf blade pale green to medium green, light glossy at above surface, more glossy at beneath surface. Inflorescence solitary, 20–26 cm long, brownish. Peduncle slight pressed, 3.0– 4.5 cm long, size 3 × 1.5 mm at crossing section, dull white, light green, covered by many brown dots. Spathe 13–18 cm long, with 2 portions tube and lamina, separated by a constriction; tube ovate, 1.5- 2.0 cm long, 1.0–1.5(2 cm) diam. at base, brown outside, pale green inside; spathe lamina triangular, 12–16 cm long, lower half wide triangular when spread out, up to 4.5 cm wide, convolute, upper half narrow and elongate triangular, outside surface brown- pale green, dark brown inside surface. Spadix 18–22 cm long; female portion conical, 4 mm long, 4–5 mm diam. at base, c. 3 mm at top, purple, brown, sometime mix with yellow; sterile portion between male and female 1.5–2.2 cm long, base covered by sterile, naked and smooth above; male portion cylindrical, 8 × c. 4 mm, stamens scattered arrange, bright yellow. Appendix stipitate, quite distinguished, a little slender than base of appendix, a little ledge between connect point to appendix, light brown-yellow, 1.5–2.0 cm long; appendix slender subulate form, 14–17 cm long, 2–3 mm diam. at base, dark brown. Ovary ovate, slight elongate, c. 1.5 mm long, 1 mm diam., pale green or slight yellow at background, covered by spots or dark brown or purple dots at apex, stigma discoid, purple or yellow at middle, 1 cell with 1 basic ovule. Stamen free, size 1.5 × 1.5 mm, anther with elliptic, open by lateral slit, yellow. Staminodes subulate, pressed, 7–8 mm long, 1 mm wide, light yellow, up ward with angle 70–80 o from spadix axis, folded 180 o at 1/3 apex or rarely straight.

Ecology: —Tropical humid, semi deciduous forest on low land at 150 m above sea level.

Eponymy: — he specific epithet is derived from the name of Phuoc Binh National Park of Ninh Thuan Province .

Phenology: —Flowering in March, blossom from midnight to morning for about 2 days; slightly bad smell.

Distribution: —Only in Vietnam, Ninh Thuan Province, Bac Ai District, Phuoc Binh Commune, Phuoc Binh National Park.

Habitat: —The plant grows on sand in rock gaps or in streamline bank, very wet and open places.

Conservation: — T. phuocbinhense has been known in one locality only, with a very small population (about 1 km radius), and not many individuals (about 500) in Phuoc Binh National Park of Ninh Thuan Province. However, in Ninh Thuan, the Bac Ai hydropower program is going to be carried out in 2020, this program could change the flows of rivers and stream lines in this area. This change could affect directly or indirectly to the habitat of species in the area. Based on criterions of IUCN, the species could be placed at EN B2 C2.