Typhonium culaochamense, Luu, Nguyen-Phi & N.T.Tran, 2024

Luu, Hong Truong, Tran, Ngoc Toan, Nguyen, Tran Quoc Trung, Phan, Cong Sanh & Nguyen-Phi, Nga, 2024, Two new species of Typhonium (Araceae) with bicolored staminodes from Central Vietnam, Phytotaxa 633 (2), pp. 163-170 : 166-168

Typhonium culaochamense, Luu, Nguyen-Phi & N.T.Tran , sp. nov. ( Fig. 2)

Typhonium culaochamense is most morphologically similar to T. filiforme Ridley (1904: 45) in having a green-brownish lanceolate spathe limb as long as its pale brown spadix appendix, a stipitate appendix with an abruptly expanded base and bicolored, subulate recurved staminodes but differs from the latter by having large habit (15–30 cm versus 10-15 cm tall), elongate, cylindrical (versus broad flattened) tuber, variable (versus triangular ovate and distinctly hastate) leaf blades, longer spathe tube (12–14 mm versus 6–7 mm), basically externally green-brownish (versus greenish yellow or whitish) spathe limb, 3–5 (versus 1–2) rows of pistils, ovaries with (versus without) brownish dots at apex, disciform (versus flattened) stigmas and curved (versus straight or curved) staminodes with yellow (versus white) acumen.

Type:— VIETNAM. Quang Nam Province, Hoi An City, Tan Hiep Commune, Cu Lao Cham Island ; 15 ⁰57’30”N 108 ⁰30’52”E, 220 m in elevation; March 24, 2017; Tran Ngoc Toan CLC29 (holotype SGN!, isotypes SGN!, PHH!) .

Herb seasonally dormant, 15–30 cm tall; tuber rhizomatous, underground, elongate, cylindrical, 1.6–2.8 cm long, 0.7–1.1 cm diameter, producing many stout roots, beige outside, cream with pink dots inside. Leaves 1–3. Petiole smooth, slender, 4–26 cm long, 2–3 mm diameter, green to grey-green with brownish mottling. Leaf blades variable, entire to pedate, green above, pale green beneath; entire blades deltoid to lanceolate, 3.5–4.5 cm long, 3.0– 3.5 cm wide, with obtuse apex; pedate blades with 3–5 linear, ovate, lanceolate or oblanceolate leaflets; leaflets 3.5–8.0 cm long, 4.5–14.0 cm wide, sessile or petiolulate. Inflorescence 1–2, slightly foetid smelling; peduncle aboveground, longer than petiole sheath, pale pink with reddish mottled, 2.5–3.5 cm long, 3.0– 3.5 mm diameter; spathe 9.5–11.5 cm long; spathe tube aboveground, separated from the limb by a constriction, ovoid or ellipsoid, 1.2–1.4 cm long, 1.0– 1.1 cm wide, outside pale pink with brownish dots, inside similar but darker; spathe limb lanceolate, 8.5–10.0 cm long, 1.3–1.7 cm wide in the middle, ending with acute tip, outside green-brownish with dark brownish mottling, inside similar but darker; spadix equaling spathe in length, sessile, erect; female zone conical, 2.5–3.0 mm high, ca. 5 mm in diameter at base, with 3–5 rows of crowded pistils; ovary obovoid, 1.3 mm high, 0.8 mm diameter, translucent cream with brownish dots at apex, 1-locular, with 1 basal ovule; stigma sessile, disciform, 0.4 mm diameter, reddish pink penicillate; sterile zone contiguously female zone, 10–13 mm long, lower part covered with 3–4 rows of staminodes, 2.5–3.0 mm long, upper part naked; staminodes filiform, subulate, 3.5–4.0 mm long, ca. 0.6 mm diameter, downward curved or folded toward axis, pinkish, pale purple verrucose, with bright yellow and slightly swollen apex, turning pale purple at fruiting stage; male zone cylindrical, 3.5–4.5 mm long, 2.5–3.0 mm in diameter; stamens free, densely arranged; thecae pale yellow to pink, opening by elongate slit; pollens orange; appendix stipitate, pale brown, smooth, filiform, tapering to apex, 9.0– 9.5 cm long, 3.5–4.5 mm diameter at base, with acute apex, abruptly expanded and more or less truncate base; stipe brownish. Fruits bulb-shaped, ca. 3.5–4.0 mm long, ca. 2 mm diameter, creamy white, with persistent staminodes.

Etymology: —The species is named after the type locality, Cu Lao Cham Island.

Vietnamese name: —Bán hạ Cù Lao Chàm.

Ecology: —The new species was found growing in clumps on humid soils between granite crevices under the canopy of a lowland evergreen forest. It appears in February to April and becomes dormant in May to January. Flowering and fruiting were seen in March to April.

Distribution: — Typhonium culaochamense has been recorded only from the type locality.

Proposed IUCN conservation status: — Vulnerable D1+D2 ( IUCN Standards and Petitions Subcommittee 2022). The species is endemic to Cu Lao Cham Island of around 13 km 2. The total number of individuals is estimated to be less than 500.

Notes: —The new species is morphologically closest to T. filiforme from Thailand and Malaysia ( Boyce et al. 2012, Mansor et al. 2011) but they are distinguishable by several key characters as stated in the diagnosis. More morphological differences are presented in Table 2. The other Typhonium species with bicolored staminodes are different from this new species as their staminodes are upward directed straight or slightly curved and are red with a light yellow acumen (in T. blumei ), 6–7 mm long and flattened and obtuse or truncate at apex (in T. bicolor ), spathulate-linguiform or subulate with or without purple at apex (in T. flagelliforme ), cylindrical and crimson red with a bright yellow to white acumen (in T. kbangense ) and rod-shaped, pink with a dirty yellow and truncate apex (in T. ramosum ).