ALOCASIA ROSEUS
ORIGINAL DESCRIPTION:
Alocasia roseus is described as a new species from Aceh Besar Regency, Sumatra (Indonesia). The plants found produce stunning inflorescences, leading to over-collecting in the wild. The new species is morphologically similar to Alocasia flemingiana but differs by its greyish green adaxial leaves and pale reddish to greenish purple or pale brownish green abaxial leaves, lacking interprimary veins and sinus not naked, thecae overtopped by synconnective, and a pale pink appendix. The new species is also similar to Alocasia arifolia, from which it differs by the glabrous and pale dull green petiole, the colour of abaxial and adaxial leaves, not forming interprimary vein, sinus not naked, and pale pink appendix.
Ni Putu Sri Asih, Ina Erlinawati, Yuzammi, Julisasi Tri Hadiah
SYNONYMS: N/A
DISTRIBUTION: Indonesia | Kueh Kemukiman Keude Bieng, Kueh Village, Aceh Besar Regency, Aceh Province, Sumatra
Distribution map of Alocasia roseus Asih & Yuzammi, sp. nov. showing the location where the new species was discovered in Aceh Besar (red shading). Inserts: overview of Indonesian archipelago (right) and Aceh Province (left). Map by Rani Yudarwati.
CLIMATE: Subtropical humid climate
Humidity is moderate throughout the year, ranging from 60% to 70%
Temperature is varies between the seasons - within the range of 48°F/9°C to 88°F/31°C during the day. Minimum temperatures never dip below 45°F/7°C
Rainy and humid season (October to May) and a dry season between June and October. The average annual rainfall is 1,200 mm
ECOLOGY: The species is only known from Aceh Besar, Sumatra Island. It grows on the hillside of the forest, in shade and humid areas.
SPECIES DESCRIPTION:
Small herb c. 55 cm tall; rhizome erect; leaves several together; petiole 34–38 cm long, pale dull green, glabrous, faintly mottled greenish, sheathing in the lower about 1/3 of its length, pale dull green; blades leathery, sagittate, greyish green adaxially, reddish to greenish purple to pale brown greenish abaxially, margin entire; anterior lobe 12.8–14.4 cm long, 9.7–11.6 cm wide, the widest is base of anterior lobe, tip acuminate, 7 mm long; anterior costa with 4–5 primary lateral veins on each side, proximal ones diverging at 76–96° on each side then running to submarginal vein, distal primary veins diverging at 40–45° on each side, primary vein prominent adaxially then forward to marginal becoming flush to lamina, prominent abaxially, with inconspicuous axillary glands, secondary and tertiary venation flush to lamina adaxially, rather prominent and conspicuous abaxially then running to conspicuous submarginal vein inserted c. 1.5 mm from margin, interprimary collective veins absent; posterior costae diverging at 60–80°, not naked in the sinus; posterior lobes acute, 6–7.2 cm long
Alocasia roseus: A Habit; B Adaxial leaf; C Abaxial leaf; D Petiole
Photographed and edited by Ni Putu Sri Asih and Julisasi Tri Hadiah
Alocasia roseus is morphologically similar to Alocasia flemingiana and Alocasia arifolia from which it differs by having greyish green adaxial leaves and pale reddish to greenish purple or pale brownish green abaxial leaves, interprimary vein absent, sinus not naked, and pale pink appendix (vs. mid-green to dark green adaxial and green-yellowish/paler abaxial leaves, forming poorly to conspicuous interprimary vein, sinus naked up to 3 cm, and cream/pale apricot appendix).
INFLORESCENCE:
Inflorescences solitary or in pairs, subtended by green cataphylls and then dried at flower anthesis; peduncle to c. 14.6 cm long, resembling petioles in colour and faintly mottled; spathe c. 9.7 cm long; lower spathe ovoid, yellowish green, c. 2.3 cm long, c. 1.8 cm diam; limb lanceolate, yellow to greenish, erect then tilted 45° after 3 days, separated from the lower spathe by a constriction at the base of male flowers or at top sterile interstice (to the midpoint of the male zone); spadix shorter than the spathe, c. 7 cm long, shortly stipitate, 2–4 mm, whitish-green, cylindric; female zone cylindric, 0.9–1 cm long, 0.9 cm wide; ovaries subglobose, green, stigma raised on a style 0.5–1 mm, conspicuously, (2–)3–4-lobed, pale yellow; sterile interstice cream-coloured, not attenuate, 0.4–0.5 cm long, narrower than male zone, with 4–5 whorls of rhomboid synandrodia; male zone cylindric, cream-coloured, 1.1–1.2 cm long; synandria rhombohexagonal to somewhat irregular, with the synconnective overtopped the thecae; thecae opening by apical pores; appendix pale pink, gradually tapering to a blunt point, faintly irregularly channeled, c. 3.5–4.2 cm long, slightly wider than the male zone; fruit unknown.
E Inflorescence with spathe; F Inflorescence with the spathe removed showing the zonation of reproductive organs; G Female zone (♀); H Sterile interstice zone(s); I Male zone (♂); J Appendix (a). Photographed and edited by Ni Putu Sri Asih and Julisasi Tri Hadiah
VARIEGATED FORMS: N/A
ETYMOLOGY: The specific epithet, roseus, is based on the pale pink appendix of the staminodes found in this new species. This color of the appendix is rarely found in the genus.
NOTES:
Alocasia roseus belongs to the informal group “Macrorrhizos” (sensu Hay 1998) in view of the following showed characteristics: inflorescences in pairs, the spathe constriction aligning with the sterile interstice of the spadix, and the synconnective overtopping the thecae. This species is the second, besides Alocasia balgooyi, in the Macrorrhizos group with no naked sinus in their posterior lobe. Alocasia roseus also has an appendix color that differs from other species in the Macrorrhizos group. Pink being a rare colour of appendix that is found only in Alocasia melo and Alocasia princeps (Hay 1998).
CULTIVARS: N/A
HYBRIDS: N/A
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