ALOCASIA KOLAKAENSIS
PROTOLOGUE: Alocasia kolakaensis , published in Taiwania 71(3): 559–565 (2026).
Alocasia kolakaensis Asih & Wibowo, sp. nov.
Type: Indonesia, South East Sulawesi, Kolaka Regency, precise location unclear, possibly Tirawuta, Ulusimbone or Lalingato villages or Uloiowi, Silui Village, 21 May 2008, AG260 (Holo: BO! subdivided into several separate sheets BO-2003739 to BO-2003752, Fig. S3). The plant cultivated in Bali Botanic Garden with accession number E20100333.
DISTRIBUTION: Sulawesi.
DISTRIBUTION NOTE: Southeast Sulawesi: East Kolaka, from Tirawuta subdistrict (Lalingato village, Uluisimbone Forest) or Uloiowi subdistrict (Silui village, Silui Mountain); the population is known from only one of those places, and no georeference is available.
SPECIES DESCRIPTION:
Robust to massive herb ca. 233 cm tall. Rhizome shortly erect and stout. Leaves up to 8 together, suberect or rather erect. Petioles 119-155 cm long, whitish purple at the sinus, glabrous, light green somewhat brownish abaxially, densely brown to dark green mottled in an oblique pattern, sheathing the lower half to almost two-thirds of the petiole. Sheath persistent, somewhat rolling out and apex truncate. Leaf blade leathery, sagittate, triangular in outline, 128.5-163 cm long, 70.2-97.6 cm wide, green adaxially, pale green somewhat with purple-tinged abaxially. Anterior lobe widest at the base, the margin sinuate, apex acuminate, thence mucronate for 8–9 mm. Anterior costa with 10 primary lateral veins on each side diverging at 45–100°. Midrib prominent adaxially and abaxially. Primary lateral veins prominent near to midrib and then flush to lamina near to the margin adaxially and abaxially. Secondary and tertiary veins join near the leaf margin to form a poorly developed intramarginal vein, secondary, tertiary and quaternary venation somewhat purple. Axillary glands conspicuous, greenish white. Posterior lobes with the inner side oblong, naked 0.5–2 cm, and the sides near the base are (the widest) stacked on top of each other, the posterior costae diverging at 60-75°.
INFLORESCENCE:
Inflorescence to ca. 14 together, clustered and each pair interspersed with a cataphyll and prophyll. Peduncle 25–49 cm long slender than petiole, light green. Spathe ca. 27.5 cm long, light green to pale yellow. Lower spathe constricted 5–5.5 cm from the base and ovoid. Spathe limbs erect then decurved after anthesis, ellipsoid, ca. 22 cm long, mucronate, externally pale yellow greenish, interior pale yellow. Spadix shorter than the spathe, ca. 22.1 cm long, not stipitate. Pistillate flower zone 3-4 cm long; ovaries globose, pale yellow, closed-packed. Style very short 0.5 mm. Stigma 3–5-lobed, the lobes conic, yellowish. Sterile interstice, cylindric, slender, ca. 2.5 cm long, with 6–8 whorls of rhombohexagonal synandria, pale cream. Staminate flower zone cylindric 7.8–8.2 cm long, cream, rhombohexagonal, not overtopped by synconnective. Appendix ca. 8 cm long, smooth, appears to have holes forming short irregular lines when photographed with macro, slightly thicker than the male zone, attenuate, white. Fruiting spathe purple greenish, ovoid, 6.8–9.5 cm long. Fruit orange, melon-like smell when ripe.
ECOLOGY:
Found in steep-sloped mountain forest on reddish soil containing layers of limestone, as recorded for Silui Mountain and Uluisimbone Forest; its habitat and ecology are otherwise not well known.
DISTRIBUTION MAPS:
ETYMOLOGY:
Named for Kolaka, the regency in Southeast Sulawesi where the species occurs. The Latin suffix-ensis means “of” or “belonging to” that place.
NOTES:
1. Diagnosis: Alocasia kolakaensis resembles Alocasia megawatiae in terms of robust herb habit, out-rolled winged sheath and clustered inflorescences. However, it differs in having a glabrous petiole; suberect leaves; spathe constriction aligned with the sterile interstice, and an ovoid lower spathe; purple-greenish fruiting spathe (vs hairy petiole; almost horizontally leaves; spathe constriction aligned with the upper part of male flower, and very elongate or somewhat cylindric lower, white fruiting spathe). This species also shows similarity to Alocasia macrorrhizos in its massive herbaceous form, suberect leaves, overlapping inner surfaces of the posterior lobes, and a spathe constriction corresponding to the sterile interstice. Nevertheless, it is distinguished by its purple tinge on the abaxial leaf surface, as well as on the secondary, tertiary and quaternary venation; clustered inflorescence, male flowers not overtopped by synconnective; white appendix (vs no purple tinge on the abaxial leaf surface, the secondary, tertiary and quaternary venation; paired inflorescence; male flowers overtopped by synconnective; yellowish appendix).
2. Alocasia kolakaensis belongs to the Puber group, which the authors characterize by a massive arborescent habit, numerous, frequently pubescent leaves, and inflorescences produced in dense central clusters without interspersed foliage leaves. Within the group it is distinguished by the smooth surface of the petiole, the absence of a gland at the lower spathe, the entire male zone outside the lower spathe chamber, and fruits that emit a melon-like scent when ripe. Alocasia megawatiae is the only other member of the group recorded from Sulawesi.
3. Alocasia kolakaensis also shares similarities with Alocasia balgooyi in being a massive herb with a stout rhizome, closed-packed pistils and a fruiting spathe that changes in color. It differs from Alocasia balgooyi by the presence of conspicuous axillary glands, a purplish tinge on the abaxial leaf surface, clustered inflorescences, thecae not overtopped by the synconnective, a smooth appendix, and a fruiting spathe that turns purplish green.
4. Described from a plant collected on May 21st, 2008, and grown on at Bali Botanic Garden. The species is known from a single location in Southeast Sulawesi whose exact site is unknown, and with distribution and population data inadequate the authors propose it as Data Deficient (DD) under the IUCN criteria.
REFERENCES:
1. Taiwania 71(3): 559–565 (2026) — protologue.