Areca unipa

Areca (ah-REHK-ah) unipa (oo-NI-pa)
Scientific Classification
Genus: Areca (ah-REHK-ah) Species: unipa (oo-NI-pa)
Synonyms
None set.
Native Continent
Asia
Morphology
Habit: Solitary Leaf type: Pinnate
Culture
Survivability index
Common names
None.

Habitat and Distribution

Areca unipa Heatubun, sp. nov.

Habitat:—This species grows in primary lowland peat forest at an elevation of about 200 m above sea level. It appears to be adapted to extreme conditions of the coal beds, which sometimes lack any apparent soil, except for leaf litter over the coal outcrop. Other palms observed growing in association with this new Areca include Calyptrocalyx sp., several species of Hydriastele, Linospadix albertisianus (Becc.) Burret (1935: 331), Licuala beccariana Furtado (1940: 37), Licuala bifida Heatubun & Barfod (2008: 431) and Sommieria leucophylla Beccari (1877: 67).

Type:—INDONESIA. West Papua Province: Maybrat Regency, East Aifat District, Ayata village, PT. Bima Cakrawala Nusantara Mining Concession Area, 200 m elev., 1°17’08.66” S, 132°37’28.02”, 17 July 2011, Iwanggin & Simbiak

138 (holotype MAN!, isotype K!).

Description

Solitary, slender palm tall up to 12 m high. Stem ca. 7.5 cm diam.; internodes 3–16 cm long, leaf scars 1–1.5 cm wide, not conspicuous, green near crown and dark to brownish grey near the base. Leaves 7 in crown, pinnate, ca. 119 cm long (including petiole); sheath tubular, ca. 54 cm long and ca. 7 cm wide, smooth, not fibrous, shiny cream to light green become dull green; crownshaft well defined, up to 75 cm long and up to 7 cm diam.; petiole ca. 16.5 cm long, slightly channelled adaxially, rounded abaxially; rachis slender, ascending but not arching, with adaxial longitudinal ridge, rounded abaxially; 9−10 leaflets on each side, more or less regularly arranged, spaced by 9–15 cm, basal leaflets ca. 42 × 1−4 cm, with 3 folds, sigmoid, middle leaflets 41−44 cm long, 1.5−2.5 cm wide at base and 7.5–11 cm wide at the tip, with 5 folds, sigmoid, terminal leaflet pair 14 cm long, 2–4 cm wide at the base and 4–7 cm at the tip, with 3–6 folds, broadly wedge-shaped to slightly cuneate, notched tips, the second and third leaflet pairs below the terminal pair splitting between the folds to about half way to the base, papery, discolorous, darker adaxially than abaxially. Inflorescence infrafoliar, slender, 30−40 cm long and 10−15 cm wide, protandrous, branching to 2 orders; prophyll elongated, slender, up to ca. 26 × 2 cm (very young stage), two-keeled, leathery, cream, light green near the apex; peduncle 1−4.5 cm long, green with numerous stellate hairs; rachis cream to yellowish green with thick rusty brown indumentum of stellate hairs; rachis bracts caducous; rachillae up to 21 cm long and 1−4 mm wide, slender, pale green, elongate and sinuous near the base; floral clusters distichous on rachillae, only one complete triad including female flower occurring at the base of each rachilla, remaining clusters comprising very few paired and solitary staminate flowers. Staminate flowers small, sessile, triangular, elongate or teardrop shaped, 4.5–6 × 2.1–2.5 mm in bud, asymmetric; sepals 3, low, ca. 2.1–2.5 × 1.1–1.5 mm, united at the base; petals 3, triangular, elongate or spathulate, 4.2–5 × 2.1–3.5 mm, striate; stamens 6, small, 2.2–2.8 mm long and 1 mm wide; filaments thick, 0.9 mm long and 0.1–0.4 mm wide, darker than anther; anthers ca. 2.2 mm long and 0.6 mm wide, sagittate, longer than the filaments; pistillode longer than stamens, 2.5–3.2 × 0.8– 1 mm, trifid. Pistillate flowers larger than the staminate, triangular, borne on the enlarged basal portion of rachillae, only one per rachillae, buds varying greatly in size depending on stage of development, 1.1 × 0.9 cm (in bud) to 2 × 1 cm (in late anthesis); sepals 3, strongly imbricate, ca. 1.5 × 0.9 mm in late anthesis, triangular, asymmetrical, striate; petals 3, imbricate, triangular, ca. 1.3 × 0.8 mm in late anthesis, striate; gynoecium 7–12 mm long and 3–5 mm; stigma ca. 3 mm long, pointed with 3 lobes, 0.3 mm long; style ca. 5–9 mm long; staminodal ring encircling gynoecium, 2 mm high, lacking differentiated staminodes. Fruit obovoid or ovoid with beak at the apex, 5.5−6 × 3.5−3.8 cm (unripe fruits), beak 4−6 mm long and 5–6 mm in diam.; epicarp smooth, shiny, dark green (unripe), mature fruits not seen; mesocarp fibrous, 0.5 cm thick, 1.5 cm thick at the base (below the seed); endocarp very thin, adhering closely to the seed. Seed obovoid, slightly flattened at base, ca. 3 × 2.2 cm (from unripe fruits); endosperm ruminate. Eophyl bifid. (Figures 1 & 2). Distribution:—Known only from the type locality in PT Bima Cakrawala Nusantara (a coal mining company) concession area, close to Ayata village in East Maybrat District, Maybrat Regency in the central part of the Bird’s Head Peninsula, West Papua Province, Indonesia

Culture

Cold Hardiness Zone: 10a

Comments and Curiosities

Uses:—The fruits are chewed as a betel nut substitute. However, the palm has potential as an ornamental. Conservation status:––Critically Endangered CR B2ab (ii,iii,v), C1, E (IUCN 2012). This palm meets the criteria for the extinction risk category Critically Endangered (IUCN 2012) because its area of occupancy is estimated to be less than 10 km2 and it is known to exist only in one population in a single locality. Habitat loss from both coal mining and oil palm plantation were identified as the major threat not only for this new species but also to the other plants in the region. It is projected that the area of occupancy, the area, extent and quality of habitat and the number of mature individuals will decline due to the coal mining activities. In addition, population size is estimated to number less than 250 mature palms. Plants occur at low density, with only two mature individuals found within a 10 ha plot. We also believe that the population will decline due to traditional harvesting by local people for the fruits as betel nut substitute, which they collect by chopping down mature individuals. The combination of threats faced by this very rare species strongly support our assessment of Critically Endangered.

Etymology:—The specific epithet refers to the acronym of Universitas Papua (the State University of Papua—UNIPA). This new species is named in celebration of the 10th anniversary of Universitas Papua and formalizes its nickname “pinang unipa”

Areca unipa. A. Slender habit with long petioled leaves and the sigmoid multifold leaflets and broadly wedge-shaped terminal leaflets. B. Inflorescence starting to expand after the prophyll has fallen off. C. Infructescence with several young fruits. All photos were taken from the holotype specimen (Iwanggin & Simbiak 138) in the forest near Ayata Village, East Maybrat, Maybrat, West Papua, Indonesia. All photos by Marthinus P. Iwanggin.

Areca unipa. A. Habit. B. Apical portion of leaf. C. Middle and basal portion of leaf. D. Half portion of inflorescence. E. Staminate flowers on rachilla. F, G. Staminate flower whole and in section. H, I. Pistillate flower whole and in section. J. Detail of ovary and staminodal ring. K. Fruit. Scale bar: A = 75 cm; B, C = 8 cm; D = 4 cm; E, J = 7 mm; F, G = 2.5 mm; H, I = 1 cm; K = 3 cm. All from Iwanggin & Simbiak 138. Drawn by Lucy T. Smith.