Rhopaloblaste gideonii Banka, Kew Bull. 59: 56 (2004)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Bismarck Archipelagopresent (World Checklist of Arecaceae)B
Known only from the type locality in the Hans Meyer Range, New Ireland. (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Discussion

  • This new species is known only from the type locality and cannot be readily equated with other species. It is easily distinguished from two of the Papuasian species, R. ledermanniana and R. elegans, on account of its robust fruit-bearing rachillae. It resembles R. ceramica in its moderately robust fruit- bearing rachillae, but differs in bearing inflorescences branched to two orders only and a smaller cupule of persistent perianth on the fruit. In R. ceramica, the inflorescences are branched to three orders and the fruit bears a large, robust cupule of persistent perianth. While the fruit on the type of R. gideonii are immature, the persistent perianth is significantly less robust than that of immature R. ceramica fruit. In addition, the type locality is disjunct from the known distribution of R. ceramica in Sandaun Province, Papua New Guinea. (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Diagnosis

Biology And Ecology

Etymology

  • Rhopaloblaste gideonii is named for the collector of the type specimen, Osia Gideon, formerly Principal Botanist at the LAE Herbarium (Papua New Guinea Forest Research Institute), now lecturer in the Biology Department at the University of Papua New Guinea, in recognition of his contributions to botany in Papua New Guinea. (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Description

  • Moderately robust solitary palm. Stem to 25 m tall, c. 20 cm diam.; leaf scars prominent; surface greyish brown. Leaf sheath 55 - 65 cm long, greyish brown, densely lepidote-tomentose with whitish brown interlocking scales; crownshaft 60 - 70 cm long, 27 - 30 cm wide; petiole short, 8 - 10 cm long, concave on adaxial surface, greyish brown; rachis 3 - 4 m long, with white to greyish brown membranous scales, denser on the adaxial surface; leaflets 100 - 103 each side of rachis, borne 2.5 - 3 cm apart, in one plane, semi-pendulous, middle leaflet 72 - 80 cm long, 1.5 - 2.5 cm wide, elliptic-linear, tapering acutely and bifid at the apex, adaxial surface green, abaxial surface light green with ramenta present sparsely along the mid veins on the abaxial surface, greyish brown to black membranous scales present on adaxial surface of mid-veins especially near the base of pinnae. Inflorescence 58 - 65 cm long, branched to 2 orders; primary branches 12 - 13, 50 - 60 cm long, basal pair of primary branches strongly recurved; prophyll 29 - 38 x 7 - 8.5 cm, silky-tomentose; peduncle 1 - 2 cm long, 1.5 - 2.3 cm diam.; rachillae moderately robust, 42 - 54 cm long, 6 - 6.5 mm diam. Staminate flower symmetric, 7 - 7.5 mm long, 3.8 - 4.1 mm diam. at anthesis; sepals 2.4 - 2.5 x 2 -2.4 mm, rounded and imbricate; petals 6 - 6.1 x 4 - 4.1 mm, broadly elliptic; stamens 6.6 - 6.8 mm long, filaments 2.5 - 3 mm long, connate at the base, anthers 3.7 - 3.8 mm long, 1 - 1.1 mm diam., elliptic; pistillode conical, 3.5 - 3.6 mm long, 1 - 1.2 mm diam. at the base. Pistillate flower 5 - 5.5 mm long, 5.2 - 5.4 mm diam., borne abundantly on the proximal portion of the rachillae, then fewer distally; sepals 4 - 4.1 x 5.8 - 6 mm, rounded and asymmetrical; petals 4.3 - 4.4 x 3.5 - 3.6 mm, broadly elliptic, apex with 1 mm acute tip, sparse brownish hairs on the middle part of the margin; staminodes 4, lobes 1 - 1.1 x 0.2 - 0.3 mm at the base, acute at the apex; gynoecium 3.8 - 4 mm long, 3.3 - 3.5 mm wide, ovoid. Fruit only immature fruit seen, 16 - 18 mm long, 6 - 8 mm diam., ellipsoid-ovoid; cupule of persistent perianth 8.5 - 9 mm long. Seed not seen. (R. Banka & W.J. Baker, A Monograph of the Genus Rhopaloblaste (Arecaceae). 2004)A

Materials Examined