Wurfbainia geostachyoides Kaewsri, 2022

Kaewsri, W. & Sangvirotjanapat, S., 2022, SIX NEW SPECIES OF WURFBAINIA (ZINGIBERACEAE) FROM THAILAND, Edinburgh Journal of Botany 79 (369), pp. 1-23 : 6-10

2. Wurfbainia geostachyoides Kaewsri , sp. nov.

Similar to Wurfbainia microcarpa (C.F.Liang & D.Fang) Škorničk. & A.D.Poulsen but differs in its shorter ligule (c. 2 mm vs 7–10 mm), abaxial blade surface glabrous (vs tomentose) and lateral staminode apex truncate (vs rounded and hooded) ( Table 2 ).

– Type: Thailand, Kanchanaburi, Thong Pha Phum , Thong Pha Phum National Park , 950 m altitude, 30 v 2010, Kaewsri 223 (holotype BKF!, isotype BK!). Figures 4 , 5 .

Clump-forming herb, stem base elevated to c. 30 cm above ground by brownish stilt roots, leafy shoot slender, 0.9–1.2 m tall. Leaf sheaths dark green and brown when dried; ligule c. 2 mm long, shallowly bilobed, lobes obtuse, papery, glabrous; blades 14–16, oblong or ovate-oblong, 8–20 × 2–4 cm, base attenuate, apex caudate, 1–2.5 cm long, glabrous, sessile. Inflorescence arising from rhizome, conical to obovate, c.8 × 2.5 cm; peduncle c. 3.5 cm long; peduncular bracts broadly ovate, pale brown, glabrous, c.0.5–1.5 × 0.5–1 cm, apex acuminate; fertile bracts lanceolate-oblong, 1–1.5 × 0.4–0.5 cm, persistent, leathery, pale brown, outer surface brown pubescent, apex acuminate; bracteoles tubular, c. 7 mm long excluding ovary, apex trilobed, brown, outer surface glabrous with pubescent base. Flower c. 1.5 cm long, white; ovary cylindrical, c.3 × 2 mm, densely appressed pubescent; style glabrous; stigma clavate, ostiole narrowly transverse, glabrous; epigynous glands c.3 × 1 mm, yellow; calyx tubular, c. 11 mm long including ovary, apex trilobed and shallowly split on one side, outer surface pale brown, base pubescent; floral tube 1.1 cm long including ovary, creamy white; dorsal corolla lobe oblong, c.5 × 3 mm, membranous, apex acuminate, revolute; lateral corolla lobes equal; lateral staminodes c. 1 mm, apex truncate; labellum hooded, elliptic, c.10 × 6 mm, apex shallowly trilobed, creamy white with scattered crimson spots and dark yellow blotches at apex; stamen: filament ribbon-like, c.5 × 1 mm, creamy white; anther c.5 × 3 mm, glabrous, dehiscing lengthwise; anther crest reniform, trilobed, rounded, c.7 × 2 mm, creamy white, central lobe c.3 × 2 mm, lateral lobes c.2 × 2 mm. Fruit 2–15 per infructescence, globose, covered with fine spines, dark green and turning to dark red when ripe, c. 1–1.3 cm in diameter, fruit stalk c. 5 mm long; seeds c. 2 mm in diameter, angular, arillate.

Phenology. Flowering and fruiting between April and July.

Distribution. Known only from the type locality (see Figure 3 ).

Habitat. Dry evergreen and tropical rain forest under shrubs or trees or on hill slopes at 260–950 m altitude.

Etymology. The specific epithet refers to the distinctly woody rhizome raised above ground with stilt roots, which recalls the genus Geostachys (Baker) Ridl.

Proposed IUCN conservation category. Critically Endangered (CR). This species is found only in Thong Pha Phum National Park, Kanchanaburi Province. Two populations were observed in 2010 and 2020. They are well protected by forestry officers, but small and restricted populations are of concern. Wurfbainia geostachyoides is therefore assessed as Critically Endangered according to criterion D.

Additional specimen examined. THAILAND. Kanchanaburi: Thong Pha Phum , 14°68′85′′N, 98°40′27′′E, 30 v 2010, Kaewsri 151 (BK, BKF) .

Figures

Figure 3. Species distribution map. The unbroken-line box indicates the localities of Wurfbainia ellipticarpa, W. globosa and W. longiflora. The dashed-line box indicates the localities of Wurfbainia geostachyoides, W. parviflora and W. yingyongii.

Figure 4. Wurfbainia geostachyoides Kaewsri, sp. nov. A, Habit; B, peduncular bract; C, fertile bract; D, calyx; E, flower; F, stamen; G, staminodes; H, infructescence. Drawn from Kaewsri 223 by W. Kaewsri.

Figure 5. Wurfbainia geostachyoides Kaewsri, sp. nov. A, Habit; B, stilt roots and inflorescences; C, ligule; D, leaves; E, flower; F, flowers; G, young fruits; H, ripe fruits. All photographs of the type collection (Kaewsri 223), taken by W. Kaewsri.