Swartzia nicaraguensis (Britton & Rose) Standl.

Description

Author: Benjamin M. Torke

Type: Nicaragua: without specific locality (US North Pacific Exploring Expedition), 1853-1856 (fr), Wright s.n. (holotype: US 20008; isotype fragment: NY).

Description: Tree, to ca. 35 m; trunk muscular to sulcate in large individuals, often somewhat buttressed, to ca. 1 m in diameter, bark scaly, exfoliating in irregular scales; cambium usually with red-oxidizing exudate; young branchlets minute-strigulose, glabrescent. Stipules broadly triangular, 0.4-0.9 mm, minute-strigulose abaxially. Leaves imparipinnate, with 3-5 pairs of lateral leaflets; petioles often marginate or winged above, (1.3-) 1.6-2.3 (-4.5) cm, sparsely minute-strigulose, glabrescent; rachis usually windged above, stipellate at leaflets, 3.5-10 (-17.1) cm, sparsely minute-strigulose, glabrescent, wings to 6.5 (8) mm wide; stipels scarcely distinct from wings; petiolules 1-2.5 (-3.5) mm, glabrous to sparsely minute-strigulose; leaflet blades chartaceous, elliptic to elliptic-lanceolate or oblanceolate, the largest (4-) 5-10 (-13) x (1.2-) 1.5-4 (-4.5), the smallest (2.3-) 2.5-6 (-7.8) x 1.2-3.2 (-3.5), base acute to obtuse, apex acute to obtuse, upper surface glabrous or nearly so, lower surface minute-strigulose, glabrescent, midrib and other veins impressed above, salient below. Inflorescences borne on defoliate portion of branches, often 2-several-fasciculate, to ca. 50-flowered; axes 3-11 cm, minute-strigulose; bracts broadly triangular, 0.4-0.7 mm, abaxially minute-strigulose, estipulate; pedicels 2-4.4 mm, minute-strigulose; bracteoles lacking; flower buds ellipsoid, umbonate, 3.1-4.1 x 2.4-3 mm. Calyx glabrous internally, sparsely minute-strigulose externally; segments 3-4, 2-4.2 mm. Corolla lacking. Stamens 15-30, glabrous, arranged in single group, filaments 3.5-7 mm, anthers ovate or elliptic to oblong in outline, 1.1-1.7 mm. Gynoecium with stipe ca. 0.7-1.2 mm and glabrous to sparsely strigulose; ovary narrowly arcuate-elliptic in outline, 2.9-4.5 x 0.9-1.1 mm, mostly glabrous, often sparsely strigulose at base; style terminal or oblique, 1.8-2.6 mm, glabrous; stigma obliquely truncate to capitellate. Fruits maturing yellow to orange, glabrous; stipe 1.5-4 mm; body ellipsoid, obovoid or oblongoid, sometimes constricted between seeds, 2.2-4 (-5) x 1.2-2.3 cm, base rounded to attenuate, apex attenuate. Seeds 1-2, ellipsoid, 1.7-2.5 x 1-1.5 cm; aril bright orange to red, completely enclosing seed.

Common names: Costilla de danto (Spanish); geographic location: Costa Rica, Nicaragua; sources: Jiménez 106, Lanuza 73, Mejia 2. Drago blanco (Spanish); geographic location: Costa Rica; source: Hathaway 1659.

Distribution: Caribbean lowlands of southern Nicaragua and northern Costa Rica, slopes of the Cordillera de Guanacaste, and sporadically in the Pacific lowlands of Guanacaste, to ca. 1100 m elevation.

Ecology: Swartzia nicaraguensis occurs in well-drained, humid tropical forest, on clay or sandy soils. In the lowlands of Guanacaste, which are dominated by deciduous dry forest, the species occurs in isolated pockets in moist ravines, usually near streams or waterfalls. Pollinators are unknown, but the flowers appear to be adapted to bee pollination. Boucher (1981) reported that spider monkeys were more important than toucans in dispersing the seeds of S. nicaraguensis (referred to as S. cubensis in the publication) in Parque Nacional de Santa Rosa in Costa Rica. The monkeys were observed to feed on both opened and unopened fruits, sometimes carrying them and releasing intact seeds up to 50 m away from the parent plant. Toucans, on the other hand, were found to feed only on the mature fruit at a lesser rate than spider monkeys and did not carry the seeds away from the parent plant. Germination was reportedly enhanced for seeds that were dispersed 10 m or more due to decreased consumption by animals that destroy the seeds, such as peccaries and deer. Boucher did not specify which parts of the fruit and/or seeds were consumed by spider monkeys and toucans, although it is safe to assume that the bright red, oily aril is taken by both.

Phenology: Flowers are known from December and March, mature fruits particularly from January-April, but also from August and November.

Taxonomic notes: Swartzia nicaraguensis belongs to the Central American apetalous clade of Swartzia section Terminales. It was treated as a variety of S. cubensis by Cowan (1968) but differs consistently from that species in its much smaller stipules, less densely pubescent branchlets, leaves, and inflorescences, shorter, more appressed trichomes, and fewer lateral leaflets. The two species are also separated by a large geographical disjunction. An unpublished molecular phylogeographical study suggests that S. nicaraguensis is most closely related to S. sumorum, from which it differs most obviously in its smaller leaflets and winged leaf rachis. However, populations from the Rio San Juan basin of Nicaragua and Heredia state of Costa Rica are genetically divergent and may be somewhat intermediate between the two species. Morphologically, they are more similar to S. nicaraguensis, but there is little material in flower available for comparison.

Uses: No uses have been recorded.

Conservation status: Swartzia nicaraguensis is not currently threatened. In a brief field-survey of the range by Torke in 2005, the species was found to be relatively common, particularly in the eastern portion of its range. Populations in southwestern Nicaragua and Heredia seem to have lower abundance and may deserve greater attention given their apparent genetic divergence from the remainder of the species. Swartzia nicaraguensis occurs in a number of protected areas in Costa Rica, including Parque Nacional de Guanacaste, Parque Nacional de Rincón de la Vieja, Parque Nacional de Santa Rosa, Reserva Natural de Vida Silvestre Caño Negro, and the Organization for Tropical Studies' La Selva Biological Station. In Nicaragua, it has been reported from the Refugio de Vida Silvestre Los Guatuzos and the Reserva Indio-Maíz.

Map Distribution

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