phytotaxa - Magnolia Press

without a beard of spines at the bases adaxially, without spinules or dense tomentum at the bases adaxially;
basal pinna 24.5(14.5–32.0) cm long, 5.7(3.0–9.0) cm wide; cirri well-developed, with acanthophylls, without
spines abaxially, with intermediate acanthophylls present, without a wide gap between pinnae and
acanthophylls. Inflorescences with the rachis ridged, not twisted, much thicker than the numerous, closely
spaced and spirally or irregularly arranged rachillae, each rachilla not or only briefly adnate to the rachis,
subtended by an acute bracteole and with a well-developed axillary pulvinus; peduncles 6.4(4.6–8.2) mm
wide; peduncular bracts 20.5(15.0–28.5) cm long, broad, the surfaces ribbed, brown tomentose, sparsely to
densely covered with long, straight or sinuous, briefly swollen-based, diagonally or vertically oriented spines,
these flattened or triangular in cross-section, whitish-brown proximally, black or brown distally, with
tomentose margins; rachillae 33, glabrous or scarcely tomentose initially; proximal rachillae 8.5 cm long,
1.0(0.7–1.2) mm wide; stamens 6; fruits 13.8(12.7–14.5) mm long, 11.3(9.1–13.8) mm wide, the surfaces
uneven with numerous, subepidermal, short, often branching (Y-shaped) fibers; fruiting corollas less than one
quarter as long as fruits, splitting irregularly into 3 lobes, the lobes often splitting again; endocarps globose to
obovoid with rounded or slightly peaked apices, the pores lateral.
Distribution and habitat:—From 9°34’–10°02’N and 82°36’–83°26’W on the Caribbean coast of Costa
Rica at 128(1–400) m elevation in lowland rainforest (Fig. 5).
Taxonomic notes:—Desmoncus costaricensis is characterized by its leaves with few spines and large
pinnae. See Grayum (1998) for a discussion of the nomenclature of this species.
Subspecific variation:—One specimen (Mora 580) is tentatively included here. It is from the same
locality as other specimens of Desmoncus costaricensis but the leaf, possibly from a juvenile plant, is
considerably smaller.
4. Desmoncus giganteus Henderson (1995: 225).
Type:—BRAZIL. Acre: Rio Moa near mouth of Rio Azul, 7°25'S, 73°15'W, 14 February 1992, A. Henderson, F. Chávez
& J. Guedes 1688 (holotype INPA!, isotypes K!, NY!).
Plants 22.3(4.5–50.0) m tall; stems 4.4(4.0–4.8) cm diameter, solitary. Leaf petioles 20.5(15.0–30.0) cm
long; rachises 157.5(125.0–190.0) cm long, 12.2(10.1–14.2) mm wide, the spines usually >1 cm long, mostly
adaxial or lateral, straight with briefly swollen bases; pinnae 10 per side of rachis, without long, filiform
apices, with an adaxial beard of spines at the bases, without spinules or dense tomentum at the bases
adaxially; basal pinna 39.2(32.0–46.5) cm long, 6.5(5.7–7.3) cm wide; cirri well-developed, with
acanthophylls, without spines abaxially, with intermediate acanthophylls present, without a wide gap between
pinnae and acanthophylls. Inflorescences with the rachis ridged, not twisted, much thicker than the numerous,
closely spaced and spirally or irregularly arranged rachillae, each rachilla not or only briefly adnate to the
rachis, subtended by an acute bracteole and with a well-developed axillary pulvinus; peduncles 8.5(6.5–11.7)
mm wide; peduncular bracts length no data, broad, the surfaces ribbed, brown tomentose, densely covered
with long, straight or sinuous, briefly swollen-based, diagonally or vertically oriented spines, these flattened
or triangular in cross-section, whitish-brown proximally, black or brown distally, with tomentose margins;
rachillae number no data, glabrous or scarcely tomentose initially; proximal rachillae 16.0 cm long, 1.7 mm
wide; stamens number no data; fruits 36.2(21.5–42.6) mm long, 16.6(12.7–18.3) mm wide, the surfaces
smooth, without any apparent subepidermal fibers; fruiting corollas to half as long as fruits, splitting
irregularly into 3 lobes, the lobes often splitting again; endocarps ovoid to obovoid with prominent, peaked
apices, the pores lateral.
Distribution and habitat:—From 0°32’–7°25’S and 70°10’–78°15’W in the western Amazon region in
Colombia, Ecuador, Peru, and Brazil at 266(150–440) m elevation in lowland rainforest or secondary forest
(Fig. 5).
22 Phytotaxa 35 © 2011 Magnolia Press
HENDERSON