Desmoncus madrensis Henderson, Phytotaxa 35: 31 (2011)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Perupresent (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A
From 9°18'-12°50'S and 69°03'-74°32'W in the western Amazon region in Peru (Madre de Dios, with an outlying specimen in Ucayali) at 273(184-400) m elevation in lowland rainforest . (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Discussion

  • Taxonomic notes:-Desmoncus madrensis differs from D. loretanus in its spiny peduncular bracts and from D. polyacanthos in its fruit surfaces with Y-shaped fibers.
    Subspecific variation:-The outlying specimen in Ucayali may be an artifact of insufficient collecting. (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Description

  • Plants 4.0(2.5-6.5) m tall; stems 0.7(0.5-0.9) cm diameter. Leaf petioles 5.9(2.5-9.0) cm long; rachises 28.7(19.5-35.0) cm long, 2.1(1.5-2.8) mm wide, the spines usually <1 cm long, mostly abaxial, recurved with markedly swollen bases; pinnae 5(4-6) per side of rachis, without long, filiform apices, without a beard of spines at the bases, with uneven surfaces at the bases adaxially, usually covered with spinules and/or dense tomentum; basal pinna 12.0(8.8-21.0) cm long, 2.5(1.6-4.5) cm wide; cirri well-developed, with acanthophylls, with few spines abaxially, mostly on proximal part only, with no intermediate acanthophylls present, usually with a wide gap between pinnae(i.e., gap wider than that between adjacent acanthophylls). Inflorescences with the rachis angular, slightly twisted, thicker than the few to numerous, closely spaced and spirally arranged rachillae, each rachilla not (or very rarely) adnate to the rachis, subtended by an acute bracteole and with a well-developed axillary pulvinus; peduncles 2.2(1.6-2.9) mm wide; peduncular bracts 22.3(18.0-26.5) cm long, broad, the surfaces ridged, brown tomentose, sparsely to densely covered with short, recurved, markedly swollen-based, diagonally oriented spines, these triangular in cross-section, whitish-brown proximally, brown distally, with tomentose margins; rachillae 14(10-17), glabrous or scarcely tomentose initially; proximal rachillae 5.6(2.3-15.0) cm long, 1.1(1.0-1.2) mm wide; stamens no data; fruits 10.4(9.3-11.4) mm long, 6.8(6.1-7.2) 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 narrowly ellipsoid with rounded apices, the pores lateral. (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Bibliography

    A. Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011