Geonoma epetiolata Moore 1980
Creators: name: Henderson, Andrew
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Arecales
Arecaceae
Geonoma
Geonoma epetiolata

description: 20. Geonoma epetiolata Moore (1980: 28). Type: PANAMA. Veraguas: Guabal (Dos Bocas del Río Calovébora), about 16 km NW of Santa Fé, 500 m, 15–16 November 1974, R. Dressler 4777 (holotype BH!, isotypes MO!, PMA! US!).
Plants 1.4(0.6–3.0) m tall; stems 1.6(0.5–3.0) m tall, 0.7(0.5–1.1) cm in diameter, solitary or clustered, canelike; internodes 1.2(0.6–2.6) cm long, yellowish and smooth. Leaves 9(8–10) per stem, undivided, not plicate, bases of blades recurved against the rachis; sheaths 5.8(3.0–8.2) cm long; petioles absent; rachis 34.1(18.8– 50.5) cm long, 4.5(2.2–7.5) mm in diameter; veins raised and rectangular in cross-section adaxially; pinnae 1 per side of rachis; basal pinna forming an angle of 14(4–24)° with the rachis; apical pinna 9.0(5.2–14.0) cm long, forming an angle of 30(16–45)° with the rachis. Inflorescences unbranched; prophylls and peduncular bracts ribbed with elongate, unbranched fibers, both bracts tubular, narrow, elongate, closely sheathing the peduncle, more or less persistent; prophylls 8.9(7.0–12.7) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 7.6(7.0–8.7) cm long, welldeveloped, inserted 2.5(1.0–5.6) cm above the prophyll; peduncles 10.2(5.0–15.0) cm long, 2.3(1.3–3.2) mm in diameter; rachillae 1, 20.3(9.0–38.0) cm long, 3.4(1.7–4.9) mm in diameter, the surfaces without 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 usually spirally arranged, sometimes tricussately, then the groups not closely spaced nor consistently arranged throughout the rachillae, 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 almost directly onto the filament apices, the connectives bifid but scarcely developed; anthers short and curled over at anthesis; non-fertilized pistillate flowers persistent after anthesis; staminodial tubes lobed, the lobes not spreading at anthesis, not acuminate, those of non-fertilized flowers not projecting and persistent after anthesis; fruits 8.6(7.3–9.9) mm long, 5.1(4.7–5.3) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, not bumpy, not apiculate, ridged from the numerous, subepidermal, meridional, elongate fibers present, these coming to a point at fruit apices; locular epidermis without operculum, smooth, without pores.
Distribution and habitat:— From 8°31’– 10°23’N and 79°16’– 84°06’W in Costa Rica and Panama at 557(300–1200) m elevation in lowland to montane tropical rainforest (Fig. 17).
Taxonomic notes:— Geonoma epetiolata is a member of a group of four Central American species, part of the G. cuneata clade, including G. brenesii, G. monospatha, and G. hugonis. They all have unbranched or few-branched inflorescences and share the character state of the staminodial tubes being lobed at the apex, but the lobes are not spreading at anthesis and are not acuminate. Although petiole length is treated as a quantitative variable here, the short or virtually absent petiole of G. epetiolata is characteristic. This species is also characterized by its mottled leaves (Blanco & Martén-Rodríguez 2007), although this mottling is not obvious from herbarium specimens.
Subspecific variation:— There is no variation in traits, except for stem branching. There is geographic discontinuity, and specimens come from Costa Rica and several areas in Panama.
Specimens from Costa Rica and Santa Fé, Panama differ significantly from other Panamanian specimens in nine quantitative variables (stem diameter, rachis length, rachis width, basal pinna angle, apical pinna length, apical pinna angle, interbract distance, peduncle width, rachilla length)(t -test, P <0.05). However, there is variation in both depth of staminodial tube lobing (de Nevers & Grayum 1998) and flower pit arrangement, and this does not correspond to the geographic division.
Most specimens from Costa Rica have spirally arranged flower pits but some tend to be tricussately arranged. Depth of lobes of staminodial tubes varies from 0.2–0.3 mm.
Specimens from Santa Fé, Panama have spirally arranged flower pits and depth of lobes of staminodial tubes is 0.2 mm.
Specimens from Cerro Tife and El Copé, Panama have spirally to almost tricussately arranged flower pits and depth of lobes of staminodial tubes varies from 0.2–0.9 mm.
Specimens from Llano Grande, Panama have spirally to almost tricussately arranged flower pits and depth of lobes of staminodial tubes varies from 0.2–0.3 mm.
East of the Canal Zone, specimens from Cerro Brewster and Cerro Bruja have spirally arranged flower pits and depth of lobes of staminodial tubes varies from 0.4–0.7 mm.
Independently of staminodial tube lobing, there are at least four distinct populations of G. epetiolata — Costa Rica; Santa Fé; El Copé/Llano Grande/Cerro Tife; and Cerro Brewster/Cerro Bruja. However, because of the complexity in staminodial tube lobing and triad arrangement, and because there are few specimens from most sites, and the gaps between the sites in Panama may be a result of insufficient collecting, no subspecific taxa are recognized.
description: Published as part of Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), pp. 1-271 in Phytotaxa 17 on pages 70-71, DOI: 10.11646/phytotaxa.17.1, http://zenodo.org/record/3538362