Geonoma monospatha de Nevers in de Nevers & Grayum (1998: 98)

Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), Phytotaxa 17, pp. 1-271 : 103

38. Geonoma monospatha de Nevers in de Nevers & Grayum (1998: 98) . Type: PANAMA. Veraguas: Cerro Tute, just W of Santa Fé, 8°40’N, 81°05’W, 800–1000 m, 27 February 1995, G. de Nevers, A. Henderson, G. Galeano & R. Bernal 10556 (holotype PMA n.v., isotypes CAS n.v. COL! K! MO! NY!).

Plants 1.1(1.0–1.5) m tall; stems height no data, 0.5(0.3–0.7) cm in diameter, solitary or clustered, cane-like; internodes 1.4(0.4–4.0) cm long, yellowish and smooth. Leaves undivided or irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 4.6(1.5–6.5) cm long; petioles 5.1(1.5–8.5) cm long, drying green or yellowish; rachis 15.2(9.0–23.2) cm long, 1.6(0.9–2.2) mm in diameter; veins not raised or slightly raised and triangular in cross-section adaxially; pinnae 2(1–4) per side of rachis; basal pinna 9.4(5.5–15.4) cm long, 2.8(1.0–5.7) cm wide, forming an angle of 28(16–45)° with the rachis; apical pinna 5.1(4.1–6.0) cm long, 5.2(3.4–11.2) cm wide, forming an angle of 30(20–40)° with the rachis. Inflorescences unbranched or branched 1 order; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, more or less persistent; prophylls 5.1(2.2–7.4) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 0.1(0.1–0.2) cm, long, vestigial, inserted 1.7(0.9–2.8) cm above the prophyll; peduncles 5.4(3.8–7.0) cm long, 1.6(1.2–2.0) mm in diameter; rachillae 2(1–3), 3.0(2.2–4.1) cm long, 2.7(1.8–3.3) 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 spirally arranged, glabrous internally; proximal lips with a central notch before anthesis, often the two sides of the notch overlapping, 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 pistillate flowers not projecting and persistent after anthesis; fruits 6.7(6.1–7.2) mm long, 5.2(4.9–5.5) 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 8°31’– 9°42’N and 80°26’– 84°12’W in Costa Rica and Panama at 1020(300–1900) m elevation in lowland to montane rainforest ( Fig. 28 ).

Taxonomic notes:— Geonoma monospatha is a member of the G. cuneata clade, within which it belongs to a group of four Central American species, including G. brenesii , G. hugonis , and G. epetiolata . 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. Geonoma monospatha differs from other species in this group by its vestigial peduncular bract and its flattened prophylls and peduncular bracts which are not ribbed with elongate, unbranched fibers.

Subspecific variation:— Three traits (stem branching, leaf division, inflorescence branching) vary within this species. Specimens come from several separate areas but there are too few specimens to test for differences, and the gaps may be artifacts caused by incomplete collecting. The Costa Rican specimens have smaller leaves and inflorescences and come from higher mean elevations (1750 m versus 837 m).

Figures

FIGURE 28. Distribution maps of Geonoma monospatha, G. mooreana, G. multisecta, and G. occidentalis.