Geonoma occidentalis Henderson
Creators: name: Henderson, Andrew
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Arecales
Arecaceae
Geonoma
Geonoma occidentalis

description: 41. Geonoma occidentalis (Henderson) Henderson, comb. & stat. nov.
Basionym: Geonoma brevispatha var. occidentale Henderson (1995: 264). Type: PERU. Madre de Dios: Río Tambopata, Explorer’s Inn at junction with Río La Torre, 12°50’S, 69°17’W, 3 November 1991, A. Henderson & F. Chávez 1633 (holotype USM!, isotypes CUZ!, NY!).
Plants 2.7(1.5–4.0) m tall; stems 1.6(1.1–3.0) m tall, 1.3(0.9–1.7) cm in diameter, solitary or clustered, not cane-like or cane-like; internodes 1.6(0.8–3.6) cm long, yellowish and smooth. Leaves 11(5–18) per stem, irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 15.0 cm long; petioles 37.4(25.5–55.0) cm long, drying green or yellowish; rachis 43.8(35.0–57.5) cm long, 3.5(2.7–4.4) mm in diameter; veins not raised or slightly raised and triangular in cross-section adaxially; pinnae 4(2–7) per side of rachis; basal pinna 23.6(17.5–32.0) m long, 2.8(1.0–6.0) cm wide, forming an angle of 60(33–90)° with the rachis; apical pinna 14.4(11.5–17.5) cm long, 14.8(8.8–23.4) cm wide, forming an angle of 36(30– 42)° with the rachis. Inflorescences branched 2–3 orders; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, deciduous or persistent; prophylls 9.7(6.1–11.0) cm long, short, asymmetrically apiculate, the margins curved around the stem, the surfaces flat with dense, felty, brown tomentum, prophyll equal to and early deciduous with the peduncular bract, the surfaces not ridged, without unequally wide ridges; peduncular bracts 9.5 cm long, well-developed, inserted 0.3(0.1–0.5) cm above the prophyll; peduncles 6.4(3.3–9.5) cm long, 6.8(3.8–10.2) mm in diameter; rachillae 24(13–33), 25.0(15.0– 33.5) cm long, 1.8(1.2–2.6) mm in diameter, the surfaces without spiky, fibrous projections or ridges, drying brown, with faint to pronounced, short, transverse ridges, not filiform and not narrowed between the flower pits; flower pits decussately arranged throughout the rachillae, the groups of pits closely spaced, glabrous internally; proximal lips without a central notch before anthesis, not recurved after anthesis, hood-shaped at anthesis, sometimes splitting post-anthesis; proximal and distal lips drying the same color as the rachillae, joined laterally with no clear gap between them, often forming a raised cupule, the margins not overlapping; distal lips well-developed; staminate and pistillate petals not emergent, not valvate throughout; staminate flowers deciduous after anthesis; stamens 6; thecae diverging at anthesis, inserted almost directly onto the filament apices, the connectives bifid but scarcely developed; anthers short and curled over at anthesis; nonfertilized pistillate flowers deciduous after anthesis; staminodial tubes crenulate or shallowly lobed at the apex, those of non-fertilized pistillate flowers not projecting and persistent after anthesis; fruits 7.2(6.2–8.5) mm long, 5.9(5.4–6.6) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, bumpy from the numerous, subepidermal, tangential, short fibers present, these coming to a point at fruit apices; locular epidermis without operculum, smooth, without pores.
Distribution and habitat:— From 4°29’– 17°50’S and 62°53’– 73°35’W in the western Amazon region in Brazil, Peru, and Bolivia at a mean elevation of 312(150–950) m in lowland rainforest (Fig. 28).
Taxonomic notes:— This taxon was treated as a variety of Geonoma brevispatha by Henderson (1995). In the present study, this name is treated as an excluded name, and the taxon to which Henderson was referring is called Geonoma pohliana subsp. weddelliana. The similarity between the two taxa is superficial and there are many differences between them, notably in the prophylls (not available to Henderson, 1995) and in the fruits.
Subspecific variation:— Two traits vary within this species (stem branching, stem type). There is no geographic disjunction—the gap in Bolivia is likely to be an artifact of insufficient collecting. There are three outlying specimens from Brazil (Acre, Rondônia) and Peru (Loreto).
description: Published as part of Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), pp. 1-271 in Phytotaxa 17 on page 106, DOI: 10.11646/phytotaxa.17.1, http://zenodo.org/record/3538362