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Carapa akuri Poncy, Forget & Kenfack, sp. nov.

Ref. Forget, P.-M., Poncy, O., Thomas, R. S. Hammond, D. S. and Kenfack, D. A new species of Carapa (Meliaceae) from Central Guyana. Brittonia, 61 (4): 301-402. 2009. pdf

The specific epithet akuri is used by the Makushi Amerindians living in the region to name the red-rumped agouti (Dasyprocta leporina) which is likely the main seed disperser of Carapa in Guyana. Three crabwood timber types in Guyana has been distinguished in the past : red- or hill-crabwood, white- or swamp-crabwood and black-crabwood without giving any reference to scientific names. We suggest that hill-crabwood should refer to C. akuri.

Type

Guyana. Upper Demerara-Berbice Region, Mabura Hill, black water creek, 5°13’N, 58° 48’ W, 29 Nov 2003, P.-M. Forget 501 (holotype: P; isotypes: GU, MO, US). Holotype at MNHN


Origine : Libellé du pays :Guyana
Pays ISO (code) :Guyana (gy)
Localité originale : Region upper Demerara Berbice, Mabura Hill, 230 km. sud de Georgetown, Demerara Timbers Ltd. forest concession, Black Water Creek, près de la pompe d'alimentation en eau
Nom du récolteur : P.-M. Forget
Numéro de récolte : 501
Date de récolte : 2003-11-29
Coordonnées géographiques:  5° 19' 0.012'' N ; 58° 37' 59.988'' O
Note écologique : Forêt à Mora exelsa et Eperua rubiginosa, zone alluvinaire inondée en saison des pluies

Tree and leaves

Large canopy tree to 35 m tall, 80(-100) cm diam., glabrous. Bole cylindrical, branching high up to 20 m, base swollen, often with straight, robust and rounded buttresses up to 0.5 m high. Bark greyish and smooth on young individuals, flaking in rectangular to irregular patches in adult trees, reddish in slash, exudating a whitish-translucent sap; branches spreading into a dense crow

 

 


 

 



 

 

 

Leaves paripinnate, crowded at the end of branches, yellowish when young, (40-)60-115 cm long; petiole 12-28 cm long, base swollen, generally with 2 nectaries; rachis (30-)43-90 cm long, glabrous; leaflets opposite, 6-13 pairs, petiolules 1--2 cm long, lamina of basal pairs of leaflets 9-20 x 5-10 cm, apical pairs up to 16-56 x 4.5-13 cm, oblong, discolorous, apex rounded to broadly acute, mucronate, the mucro flattened laterally, thick and spatulate, glandular, base cuneate to rounded, slightly asymmetrical, midrib prominent beneath, with 8--20 secondary veins on each side, tertiary venation loose and flat.

 

 

 

Inflorescence and flowers

Inflorescences pendulous thyrses, in groups of 6-10 at the end of branches, in axils of undeveloped leaves up to 3 cm long, (35-)60-100(120) cm long, very much ramified, lower branches up to 15 cm long , transversely scurfy; peduncle 8--14 cm long.

Flowers 1-3, born in axil of a 1mm long, scaly bract; (4)5-merous, pedicel (1.5-)2-3.5 mm long, often angular in section and transversely scurfy; calyx green, lobes narrowly triangular to broadly ovate, 1-1.5 mm long, margins ciliolate; petals whitish to yellow-green, free to the base, oblong or obovate, 4-6 x 2-3.5 mm; staminal tube white, urceolate, 3.5–5 mm long, ca. 4 mm diam., with 10 truncate or more or less emarginate lobes; anthers or antherodes 10, oblong, sessile, alternating with lobes, included within the tube, ca. 0.7 x 0.4 mm in carpellate flowers, 0.7-0.9 x 0.4-0.6 mm in staminate flowers; nectary cushion-shaped, white, 0.7-1.3 x 2--3 mm; ovary 5-locular, ovoid to globose in carpellate flowers, 1-1.7 x 1.5-1.8 mm, conical in staminate flowers, 0.6-1.5 x 0.5-1.3 mm; ovules 4 per loculus; style less than 0.7 mm long in carpellate flowers, 1-1.5 mm long in staminate flowers; stigma discoid, yellow, 1.4-2 mm diameter.

Fruit and seeds

Fruit a capsule, green when immature, becoming brown at maturity, globose to ovoid 7-11 x 6-17 cm, apex often conspicuously acuminate; valves with more or less developped warty excrescences and numerous extrafloral nectaries;

Seeds 2.5-4.8 x 3-5.5 cm, up to 4 per valve; hilum oval, 4.5-12 x 1.5-6 mm; testa brown and smooth. 

Seedling

Seedlings: epicotyl 30-50 cm tall, the first leaves simple, blades discolorous, the adaxial surface pale greyish green, bright. (below: crown of a young tree)

 

 

 

 

 

Phenology

Carapa akuri as well as C. surinamensis flower annually during the dry season between November and February. Fruiting occurs in the rainy season, between February and July at the community-level fruiting peak, and toward its end. Casual fruiting may occur in November suggesting that a second peak of flowering, though weaker in intensity, may be observed during the wet season. The documented minimum tree size to set fruits is 16 cm dbh at Iwokrama forest . Seeds of C. akuri are among the largest found in Guianan rainforests (formerly identified as C. procera.

Flowering

J

F

M

A

M

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J

A

S

O

N

D

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F

M

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M

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S

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D

Fruiting

Ecology

Carapa akuri grows on various types of soils such as clay, loam, and brown sands, along large streams and in seasonally inundated forests, as well as on upland lateritic hills. At the Forest Ecological Reserve Mabura Hill and the Tropenbos Pibiri Reserve, which are both species-rich forests, only C. akuri was observed, occurring in all types of habitats, from banks of permanently wet creeks to uphill forest. In the Iwokrama forest, C. akuri is present in species-rich, non-flooded forest, several hundred meters from the river banks as well as in the periodically flooded mono-dominant Mora excelsa-rich forests near the Essequibo River. There, C. akuri occurs in habitats occupied elsewhere by C. guianensis, such as swampy areas, permanently wet forests, edges of large rivers, and C. surinamensis, such as non-flooded areas like hill slopes in Surinam and French Guiana. The seeds are an important food source for some terrestrial vertebrates such as the red-rumped agouti (Dasyprocta leporina), the collared and white-lipped peccary (Pecari tajacu & Tayassu pecari, respectively), brocket deer (Mazama spp.); some birds, such as macaws (Ara spp.), feed on the immature fruits. Scatter-hoarding rodents such as agouti and acouchy (Myoprocta exilis) are likely the main seed dispersal agents of C. akuri as observed in C. surinamensis.

Use and Conservation

The straight bole of C. akuri produces good lumber that is used locally. The extraction of oil from seeds by the Makushi communities of Kurupukari is not as extensive as that for C. guianensis in the more northern Waini River area. A large logging concession currently overlaps the known geographic range of C. akuri and the Iwokrama Forest. Within this area, this species has been harvested heavily on the assumption that it is widespread C. guianensis. The identification of C. akuri as a new species with a much narrower geographic distribution argues for a reassessment of the land use. Given the current deforestation of Central Guyana, the risk of overexploitation of C. akurifor timber, and its reduced the extent of its occurrence, we evaluate the conservation status of this species as ENB1b(i,v) following the IUCN (2001) Red List Categories and Criteria version 3.1.

References

Forget, P.-M., Poncy, O., Thomas, R. S. Hammond, D. S. and Kenfack, D.  (2009) A new species of Carapa (Meliaceae) from Central Guyana. Brittonia, 61 (4): 301-402. pdf

Kenfack, D. (2011) A synoptic revision of Carapa (Meliaceae). Harvard Papers in Botany 16 (2): 171-231.

Pierre-Michel Forget, Odile Poncy and David Kenfack

(all photos © P.-M.Forget)