Geonoma euspatha Burret 1930
Creators: name: Henderson, Andrew
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Arecales
Arecaceae
Geonoma
Geonoma euspatha

description: 21. Geonoma euspatha Burret (1930c: 10). Type: COLOMBIA. Caquetá: Sucre, 10 July 1926, G. Woronow &
J. Juzepczuk 5885 (holotype LE!).
Geonoma karuaiana Steyermark (1951: 88). Type: VENEZUELA. Bolívar: Río Karuai, base of Sororopán-teupí, W of La Laja, 1220 m, 29 November 1944, J. Steyermark 60789 (holotype F!).
Plants 1.9(0.4–3.0) m tall; stems 1.0(0.2–3.0) m tall, 1.2(0.6–1.7) cm in diameter, solitary or clustered, not cane-like or cane-like; internodes 0.9(0.3–2.2) cm long, yellowish and smooth. Leaves 9(5–14) per stem, undivided or irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 16.6(8.5–22.5) cm long; petioles 46.5(11.0–76.0) cm long, drying green or yellowish; rachis 45.4(22.0–85.0) cm long, 3.2(1.9–4.7) mm in diameter; veins raised and rectangular in cross-section adaxially; pinnae 3(1–6) per side of rachis; basal pinna 38.8(20.0–63.5) cm long, 5.9(1.5–19.0) cm wide, forming an angle of 44(27– 71)° with the rachis; apical pinna 27.7(15.0–35.5) cm long, 14.0(7.7–22.5) cm wide, forming an angle of 28(14–37)° with the rachis. Inflorescences branched 1–2 orders; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, persistent; prophylls 21.2(9.0–31.0) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 20.2(8.0–26.0) cm long, well-developed, inserted 6.8(0.3–14.0) cm above the prophyll; peduncles 30.3(6.5–46.0) cm long, 4.3(2.1– 7.6) mm in diameter; rachillae 13(2–21), 12.8(5.5–19.0) cm long, 2.4(1.5–3.4) 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 spirally arranged, densely hairy internally proximally and distally; 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, not joined to form a raised cupule; distal lips absent; 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 or 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 6.3(4.9–8.4) mm long, 5.1(3.9–6.8) 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 5°52’N– 17°23’S and 49°15’– 78°35’W on eastern Andean slopes in Colombia, Ecuador, Peru, and Bolivia, the Guayana Highland region and outlying montane areas in Venezuela, Brazil, Guyana, Suriname, and French Guiana, and just reaching the Amazon region of Brazil (Pará, Rôndonia), at 735(200–1630) m elevation in lowland to montane rainforest (Fig. 18).
Taxonomic notes:— Geonoma euspatha is the first species to be treated here of a group of related species characterized by its lack of a distal lip of the flower pit and flower pits hairy internally. This group, the G. interrupta clade, also includes G. frontinensis, G. interrupta, G. pinnatifrons, and G. simplicifrons. These species have had a checkered taxonomic history. Geonoma euspatha was included in G. interrupta by Wessels Boer (1965), but later reinstated (Wessels Boer, 1968). It differs from G. interrupta and G. simplicifrons in its flower pits which are densely hairy internally proximally and distally; from G. frontinensis in rachillae surfaces with faint to pronounced, short, transverse ridges; and from G. pinnatifrons in its prophyll surfaces without unequally wide ridges.
Subspecific variation:— Three traits vary within this species (stem branching, stem type, leaf division). There is geographic discontinuity and the species occurs in two areas: eastern Andean slopes of Colombia, Ecuador, Peru, and Bolivia; and the Guayana Highland region of Venezuela and adjacent Brazil and the Guianas. There are also outliers in the Amazon region of Brazil. Excluding the Amazon outliers, of which there are only four specimens, specimens from eastern Andean slopes differ significantly from Guayana Highland/ Guiana specimens in only four variables (rachis width, basal pinna width, peduncular bract length, number of rachillae)(t -test, P <0.05). Based on these results, no subspecies are recognized.
There is geographical variation in this species. Regression shows there are significant (P <0.05) associations between elevation and one stem, three leaf, and nine inflorescence variables. Squared multiple R for the regression of stem diameter on elevation is 0.54, sheath length 0.44, basal pinna angle 0.22, apical pinna length 0.50, prophyll length 0.38, peduncle length 0.43, peduncle width 0.12, interbract distance 0.42, rachilla length 0.19, rachilla width 0.08, number of rachillae 0.13, fruit length 0.40, and fruit diameter 0.21. Stem diameter, sheath length, prophyll length, interbract distance, peduncle length, and rachilla length decrease with elevation, and basal pinna angle, apical pinna length, peduncle width, rachis width, rachilla width, number of rachillae, and fruit length and diameter increase with elevation. In particular, inflorescences change with increasing elevation, with prophylls and interbract distances becoming shorter, peduncles shorter and wider, rachillae fewer, shorter, and narrower, and fruits larger. Wessels Boer (1968) commented on these changes with elevation.
description: Published as part of Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), pp. 1-271 in Phytotaxa 17 on pages 71-73, DOI: 10.11646/phytotaxa.17.1, http://zenodo.org/record/3538362