Desmoncus obovoideus Henderson, Phytotaxa 35: 36 (2011)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Panamápresent (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A
From 8°40'-9°30'N and 77°25'-80°29'W in central Panama, with outliers to the west and east, at 173(25-400) m elevation in lowland rainforest (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Discussion

  • Taxonomic notes:-Desmoncus obovoideus is similar to D. osensis and shares all character states except that D. obovoideus lacks data for stamen number. Desmoncus obovoideus also has shorter and wider basal pinna compared to D. osensis (mean of 14.0 cm long and 4.9 cm wide versus 23.2 cm long and 3.7 cm wide). Based on this, and geographic separation, the two are recognized as separate species. A few specimens have abaxial rachis spines which appear almost recurved, more like those of D. polyacanthos. There are two outliers, both of which are tentatively included here. The one from eastern Panama (McPherson 6961) is without fruits. The other (Hammel 1863), from central Panama, also has abaxial rachis spines which appear almost recurved.
    Subspecific variation:-In most specimens the adaxial beard of spines at the bases of the pinnae is poorly-developed. One specimen (Garwood 2178) is smaller than the others. (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Description

  • Plants 4.9(3.5-7.0) m tall; stems 1.7(1.4-2.0) cm diameter, branching no data. Leaf petioles 3.1(2.0-4.5) cm long; rachises length no data, 6.3(6.0-6.6) mm wide, the spines usually >1 cm long, mostly adaxial or lateral, straight with briefly swollen bases; pinnae number no data, without long, filiform apices, with an adaxial beard of spines at the bases, without spinules or dense tomentum at the bases adaxially; basal pinna 14.0 cm long, 4.9(4.2-5.5) 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 4.3(2.8-5.7) mm wide; peduncular bracts length no data, 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 (rarely without spines); rachillae 21(20-21), glabrous or scarcely tomentose initially; proximal rachillae 8.5 cm long, 1.0 mm wide; stamens no data; fruits 15.8(14.0-17.9) mm long, 14.2(12.8-16.3) mm wide, the surfaces uneven with numerous, subepidermal, long, branching fibers; fruiting corollas less than one quarter as long as fruits, splitting irregularly into 3 lobes, the lobes often splitting again; endocarps broadly obovoid with flattened apices, the pores lateral on or near flattened apices. (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