Geonoma oligoclona Trail 1876
Creators: name: Henderson, Andrew
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Arecales
Arecaceae
Geonoma
Geonoma oligoclona

description: 43. Geonoma oligoclona Trail (1876: 325). Type: BRAZIL. Amazonas: Barreira Branca, Rio Jutaí, 31 January 1875, J. Trail 1019/CCI (holotype K!, isotypes GH!, P!).
Plants 2.4(1.5–3.5) m tall; stems 1.8(1.0–2.5) m tall, 1.0(0.5–1.5) cm in diameter, clustered, cane-like; internodes 2.3(1.1–4.1) cm long, covered with reddish or brownish scales, especially in their distal part. Leaves 10(8–12) per stem, irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 9.7(5.0–12.0) cm long; petioles 33.2(8.5–43.5) cm long, drying green or yellowish; rachis 26.3(11.7– 36.5) cm long, 2.5(1.4–3.7) mm in diameter; veins raised and rectangular in cross-section adaxially; pinnae 3 per side of rachis; basal pinna 17.7(6.2–23.5) cm long, 2.0(1.0–4.5) cm wide, forming an angle of 72(43–97)° with the rachis; apical pinna 16.6(5.5–21.5) cm long, 11.2(5.0–16.7) cm wide, forming an angle of 35(22–42)° with the rachis. Inflorescences branched 1 order; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, deciduous; prophylls 7.0(4.2–10.0) 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 5.6(4.0–7.0) cm long, well-developed, inserted 0.4(0.2–0.5) cm above the prophyll; peduncles 6.0(4.0– 10.2) cm long, 3.5(2.0–4.5) mm in diameter; rachillae 4(3–9), 23.1(7.3–33.5) cm long, 2.8(2.1–3.6) mm in diameter, the surfaces with spiky, fibrous projections or ridges, drying brown or yellow-brown, without short, transverse ridges, not filiform and not narrowed between the flower pits; flower pits spirally arranged, glabrous internally; proximal lips without a central notch before anthesis, not recurved after anthesis, not hood-shaped; proximal and distal lips drying the same color as the rachillae, not joined to form a raised cupule, the proximal lip margins overlapping the distal lip margins; 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 onto bifid and well-developed, non-jointed connectives; anthers short and curled over at anthesis; non-fertilized pistillate flowers deciduous after anthesis; staminodial tubes lobed at the apex, the lobes not spreading at anthesis, not acuminate, those of non-fertilized pistillate flowers not projecting and persistent after anthesis; fruits 6.9(6.5–7.3) mm long, 6.3(6.2–6.4) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging; fruit surfaces not bumpy, not apiculate; locular epidermis without operculum, smooth, without pores.
Distribution and habitat:— From 4°57’N– 3°22’S and 63°01’– 70°50’W in the central–western Amazon region of Colombia, Venezuela, and Brazil (including an unmapped specimen, Kuhlmann 1236, from “ Tocantins ”, Pará) at 206(100–250) m elevation in lowland rainforest (Fig. 29).
Taxonomic notes:— This species was considered by Wessels Boer (1968) to be related to Geonoma deversa. In fact, the two are not related, and G. oligoclona forms a clade with G. aspidiifolia and G. santanderensis. All three species share internodes covered with reddish or brownish scales, rachillae surfaces with spiky, fibrous projections or ridges, and staminodial tubes lobed at the apex with the lobes not spreading at anthesis and not acuminate. Geonoma oligoclona differs from G. aspidiifolia and G. santanderensis in its prophyll which has the margins curved around the stem and the surfaces flat with dense, felty, brown tomentum.
Subspecific variation:— No trait varies within this species. The specimens come from scattered localities, but this is probably an artifact of insufficient collecting. One specimen (Galeano 1869) is much smaller than the others and is reported to come from a white sand savanna area.
description: Published as part of Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), pp. 1-271 in Phytotaxa 17 on pages 107-108, DOI: 10.11646/phytotaxa.17.1, http://zenodo.org/record/3538362