Geonoma deversa Kunth 1841
Creators: name: Henderson, Andrew
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Arecales
Arecaceae
Geonoma
Geonoma deversa

description: 16. Geonoma deversa (Poiteau) Kunth (1841: 321). Gynestum deversum Poiteau (1822: 390). Type: FRENCH GUIANA. Without locality, no date, A. Poiteau s.n. (holotype P!).
Plants 2.4(0.5–5.0) m tall; stems 2.4(0.3–7.0) m tall, 1.0(0.5–1.8) cm in diameter, solitary or clustered, canelike or not cane-like; internodes 1.9(0.5–7.5) cm long, yellowish and smooth. Leaves 11(6–18) per stem, undivided or irregularly pinnate, sometimes regularly pinnate and the pinnae with 1 main vein only, not plicate, bases of blades running diagonally into the rachis; sheaths 12.5(5.0–27.5) cm long; petioles 20.6(4.2– 82.0) cm long, drying green or yellowish; rachis 42.0(17.2–92.5) cm long, 3.2(1.4–7.0) mm in diameter; veins not raised or slightly raised and triangular in cross-section adaxially; pinnae 5(1–28) per side of rachis; basal pinna 28.5(10.5–60.5) cm long, 6.4(0.5–27.0) cm wide, forming an angle of 42(20–93)° with the rachis; apical pinna 19.9(8.8–35.5) cm long, 12.4(0.6–26.7) cm wide, forming an angle of 28(14–45)° with the rachis. Inflorescences branched 1–3 orders; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, deciduous; prophylls 6.8(3.0–13.0) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 4.8(3.2–7.5) cm long, well-developed, inserted 0.3(0.1–0.7) cm above the prophyll; peduncles 8.3(2.0–19.7) cm long, 4.2(1.9–9.0) mm in diameter; rachillae 13(3–43), 16.7(6.5–32.0) cm long, 1.9(1.0–3.4) 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 tricussately or quadricussately 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 to form 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 flowers not projecting and persistent after anthesis; fruits 6.6(4.5–8.1) mm long, 5.6(4.4–7.0) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, not bumpy and not apiculate; locular epidermis without operculum, smooth, without pores.
Taxonomic notes:— Geonoma deversa is the most wide-ranging species in the genus, occurring from Belize and Guatemala to Brazil and Bolivia. It is variable, but not as much as it’s wide range would suggest (see section on Infraspecific Variation). Its treatment here is generally consistent with that of Wessels Boer (1968), except that several subspecies are recognized. It is recognized by its flower pits which are usually tricussately arranged (sometimes quadricussately) and closely spaced throughout the rachillae.
Subspecific variation:— Three traits (stem branching, stem type, leaf division) vary within this species. Only two specimens (of 179) are scored as stems not cane-like and this trait, together with stem branching and leaf division, are not useful for subspecific delimitation in this species.
There is little geographic discontinuity, except that in Central America two subgroups are geographically isolated—in Belize and Guatemala, and the Osa Peninsula of Costa Rica. Specimens from Belize and Guatemala differ significantly from other Central American (excluding Osa Peninsula subgroup) specimens in 14 variables (stem diameter, internode length, sheath length, petiole length, rachis width, basal pinna length, basal pinna width, basal pinna angle, apical pinna length, apical pinna width, prophyll length, peduncular bract length, peduncle width, number of rachillae)(t -test, P <0.05); and specimens from the Osa Peninsula of Costa Rica differ from other Central American (excluding Belize and Guatemala) specimens in 12 variables (stem diameter, sheath length, rachis length, rachis width, number of pinnae, apical pinna length, apical pinna width, prophyll length, peduncle width, rachillae length, number of rachillae, fruit length). Based on these results, these two subgroups are recognized as subspecies (subspp. belizensis, peninsularis).
There is considerable variation in the trait pit arrangement in specimens from the western Amazon region. Some specimens from the northwestern Amazon region of Colombia, Brazil, and Peru have quadricussate flower pits rather than the more usual tricussate ones. Because of this, the subgroup is recognized as a subspecies (subspp. quadriflora), and all other specimens are recognized as subsp. deversa.
Key to the subspecies of G. deversa
1 - 2 - 3 - 4. - Central America............................................................................................................................................................ 2 South America .............................................................................................................................................................. 4 Belize, Guatemala ................................................................................................................................ subsp. belizensis All other areas .............................................................................................................................................................. 3 Rachis 38.9(17.2–80.0) cm long; widespread......................................................................................... subsp. deversa Rachis 64.5(46.5–85.0) cm long; Osa Peninsula of Costa Rica ...................................................... subsp. peninsularis Flower pits tricussately arranged; widespread........................................................................................ subsp. deversa Flower pits quadricussately arranged; northwestern Amazon region of Colombia, Brazil, and Peru ........................... .......................................................................................................................................................... subsp. quadriflora
description: Published as part of Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), pp. 1-271 in Phytotaxa 17 on pages 62-63, DOI: 10.11646/phytotaxa.17.1, http://zenodo.org/record/3538362