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Vachellia cucuyo - short shoots

Vachellia cucuyo - short shoots trunk

Vachellia cucuyo - petiole

Vachellia cucuyo - petiole gland

Vachellia cucuyo - leaf

Vachellia cucuyo - leaf

Vachellia cucuyo - inflor

Vachellia cucuyo - immature fruits

Vachellia cucuyo - flower

Vachellia cucuyo - trunk

Name

Vachellia cucuyo (Barneby & Zanoni) Seigler & Ebinger, Phytologia  87:  155.  2005.
syn.  Acacia cucuyo Barneby & Zanoni, Moscosoa 5:  14.  1989.

Synonymy and types

Basionym:  Acacia cucuyo Barneby & Zanoni, Moscosoa  5: 14.  1989. - TYPE:  DOMINICAN REPUBLIC.  AZUA:  Sierra Martín García, Loma del Copey, approximately 3 km (by air) SW of Barrero, 18o 18'N, 70o 56'W, alt. 780 m, 23 Feb 1987, T. Zanoni, J. Pimentel, & R. García 38370 (holotype:  JBSD; isotypes:  FLAS, FTG, GH, K, MO, NY, S, TEX).

Formal description

Tree to 15 m tall.  Bark dark brown to reddish brown to gray, rough; the older branches and the trunks of young trees usually bearing clusters of fusiform to aciculate, straight stipular spines to 30 mm long clustered on short shoots.  Twigs gray to dark reddish-brown, not flexuous, puberulent.  Short shoots commonly present above the stipular spines, to 2 mm long, covered with acuminate stipules and old leaf bases; these sometimes elongating to branches to 12 mm long, with scattered leaves.  Leaves alternate, also commonly clustered on the short shoots, 2-13 mm long.  Stipular spines light gray with a reddish-brown apex, symmetrical, terete, straight to slightly recurved, aciculate, to 7.5 x 0.9 mm near the base, puberulent.  Petiole adaxially grooved, 0.9-5.4 mm long, puberulent; petiolar gland solitary, located just below the first pinna pair, columnar, 0.3-0.8 mm long, glabrous, commonly inclined toward the apex of the petiole, apex circular to elliptical, 0.2-0.7 mm across, depressed.  Rachis adaxially grooved, 0-7 mm long, puberulent, lacking a gland between  the terminal pinna pair.  Pinnae 1-2 pairs per leaf, 8-32 mm long, 2-7 mm between pinna pairs.  Petiolules 0.5 to 1.3 mm long.
Leaflets 8 to 17 pairs per pinna, opposite, 0.5-2.3 mm between leaflets, oblong to elliptic-oblong, 2.6-8.2 x 0.6-1.9 mm, glabrous, lateral veins obvious, only one vein from the base, coriaceous, base oblique, margins minutely ciliate, apex acute to obtuse.  Inflorescence a densely flowered globose to subglobose head, 5-8 mm across, in fascicules of 1 to 5 from the short shoots.  Pedicels 4-14 x 0.4-0.7 mm, villous with orange hairs.  Involucre 4- to 5-lobed, located 1-2 mm below the base of the globose head, lightly puberulent, persistent.  Floral bracts broadly spatulate, 0.5-0.8 mm long, sparsely puberulent, more or less persistent.  Flowers sessile, yellowish-orange; calyx 5-lobed, 0.7-1.1 mm long, glabrous or nearly so; corolla 5-lobed, 1.5-2.3 mm long, glabrous or nearly so; stamens 18 to 27, filaments 3.8-4.5 mm long, distinct; ovary densely pubescent, on a stipe to 0.2 mm long.  Legumes dark blackish brown to dark brown, straight to slightly curved, elliptic to terete in cross section, not constricted between the seeds, oblong or nearly so, 27-60 x 8-18 mm, coriaceous, not striate, glabrous and lustrous, eglandular, dehiscent along the ventral suture; stipe 1-2 mm long; apex obtuse.  Seeds uniseriate, surrounded by a reddish-brown pulp, light to dark brown, irregularly ellipsoid to ovoid, slightly flattened, 3.3-4.9 x 2.1-3.6 mm, smooth; pleurogram oval, 2.1-2.8 mm across.  Flowers in February.
Chromosome number unknown.

Distribution

Known only from the Sierra Martín García, Dominican Republic, where it occurs in a montane, seasonally moist area at and elevation of approximately 400-800 m on limestone outcroppings with very thin soil.  Only cultivated specimens are known from Distrito National.

Additional info

Endemic to the Dominican Republic, Vachellia cucuyo is undoubtedly closely allied to other members of the V. acuifera species group.  However, this taxon is unique in several respects (Barneby and Zanoni 1989).  Vachellia cucuyo and V. zapatensis are the only members of this group that have more than a single pair of pinnae per leaf.  Acacia cucuyo and V. anegadensis are the only members of the group that have a turgid, oblong fruit; that of V. anegadensis is a considerably smaller than that of V. cucuyo.  Finally, this species is a large forest tree (to 15 m) that occurs in a montane habitat that is significantly more mesic than the habitats of the other members of this group.  Water is somewhat limited, nonetheless, as these plants grow on virtually bare limestone with very high runoff.  The population of V. barahonensis from Azua Province is only several kilometers from that of V. cucuyo, but occurs in a much more xeric habitat because of elevational differences.

Vachellia cucuyo is closely associated with the two other Hispaniolan species, V. caurina and V. barahonensis, by its stipitate petiolar gland that is commonly inclined toward the apex of the petiole, and with these two species and V. anegadensis by its involucre 1-2 mm below the inflorescence.  It is similar to V. anegadensis and V. barahonensis in having relatively few stamens per flower (18 to 27 in V. cucuyo, 35 or fewer in the other taxa).  None of the collections of this species were found to be cyanogenic, even after the addition of emulsin.

Representative specimens

DOMINICAN REPUBLIC:

 Azua Province:

Distrito Nacional Province:

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