Vachellia oviedoensis (R. García & M. Mejía) Seigler & Ebinger, Phytologia 87: 163. 2005.syn. Acacia oviedoensis García & M. Mejía, Moscosoa 11: 7. 2000.
Synonymy and types
Basionym: Acacia oviedoensis R. García & M. Mejía, Moscosoa 11: 7. 2000. - TYPE: DOMINICAN REPUBLIC. PEDERNALES: 22 km al W de Oviedo, El Papayo, lado Sur de la Carretera Oviedo-Pedernales. Bosque seco sobre roca caliza con: Guaiacum, Senna, Opuntia, Harrisia and Reynosia. 17°51'N, 71° 31'W, elev. 140 m, 13 May 1997, R. García & R. Pujols 6543 (holotype: JBSD; isotypes: B, F, MAPR, MO, NY, S).
Tree to 5 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 50 mm long clustered on short shoots. Twigs gray to dark reddish-brown, slightly flexuous, puberulent. Short shoots usually present above the stipular spines, to 2 mm long, covered with acuminate stipules and old leaf bases. Leaves alternate, also commonly clustered on the short shoots, 1.3-5.1 mm long. Stipular spines dark redish-brown, becoming gray with age, symmetrical, terete, straight to slightly recurved, aciculate, to 10.0 x 0.9 mm near the base, glabrous. Petiole adaxially grooved, 1.0-2.7 mm long, glabrous; petiolar gland solitary, located just below the first pinna pair, nearly sessile, apex circular, 0.3-0.5 mm across, glabrous, depressed. Rachis absent. Pinnae 1 pair per leaf, 1.5-6.2 mm long. Petiolules 1.5-3.0 mm long. Leaflets 1(4) pairs per pinna, opposite, 1.5-3.2 mm between leaflets, oblong to obovate, 5.0-9.5 x 2.0-5.5 mm, glabrous, lateral veins obvious, 3-7 veins from the base, coriaceous, base oblique, margins not ciliate, apex obtuse and emarginate. Inflorescence a densely flowered globose head, 5-8 mm across, in fascicles of 1 to 4 from the short shoots. Pedicels 3-5 x 0.4-0.7 mm, puberulent. Involucre 4- to 5-lobed, located at the base of the head, puberulent, persistent. Floral bracts spatulate, 0.3-0.7 mm long, sparsely puberulent, more or less persistent. Flowers sessile, bright orange to yellow; calyx 5-lobed, 0.5-1.0 mm long, glabrous; corolla 5-lobed, 1.5-2.1 mm long, glabrous or nearly so; stamens 16 to 20, stamen filaments 2.2-3.0 mm long, distinct; ovary pubescent, on a stipe to 0.7 mm long. Legumes reddish-brown to dark blackish brown, slightly curved, elliptic in cross section, not constricted between the seeds, oblong, 20-40 x 5-7 mm, coriaceous, not striate, glabrous and lustrous, eglandular, dehiscent along the ventral suture; stipe 10-20 mm long; apex acute. Seeds uniseriate, surrounded by a reddish-brown pulp, dark reddish-brown, irregularly ellipsoid to ovoid, slightly flattened, 3.0-3.8 x 2.5-3.5 mm, smooth; pleurogram oval, 1.2-2.0 across. Flowers all year. Chromosome number unknown.
Known only from the Dominican Republic in the Provinces of Barahona and Pedernales. It is found in dry secondary forest from near sea level to about 800 m (García and Mejía 2000).
Vachellia oviedoensis is a rare endemic that is restricted to a few sites on the Barahona Peninsula, southwestern Dominican Republic. The specimens available for study suggest that the species is not highly variable in its morphological characteristics and that is it a well-defined species that does not overlap in its characteristics with other members of the group. It is very distinctive species that is probably most closely related to V. anegadensis, a species restricted to Anegada Island, in the British Virgin Islands. Both species have a very limited distribution and are well differentiated from other acacias species on the basis of the combination of leaves with only one pair of pinnae, large, oblong to obovate leaflets, and mostly 1 to rarely 2 pairs of leaflets per pinna. Vachellia oviedoensis is easily separated from V. anegadensis by smaller leaflets (less than 9.5 mm long and 5.5 mm wide) and the lack of the obvious eucamptodromous venation found in V. anegadensis.
D'Arcy (1971) suggested that there was a strong floristic similarity between Anegada and Hispaniola, particularly the Barahona Peninsula. He found that 100 of 139 species from Anegada also occur in Hispaniola, and that 70 of these also occur on the Barahona Peninsula. The presence of Vachellia oviedoensis, which appears very similar to V. anegadensis, in Hispaniola and particularly on the Barahona Peninsula strengthens this assumption. It also appears that the affinities of V. oviedoensis and V. anegadensis appears to lie close to the other Hispaniolan species, V. barahonensis, V. caurina, and V. cucuyo.
- Sierra de Bahoruco, Enriquillo, N del poblado de Higüero, en el lugar llamado Sabana el Maniel, alt. 750 m, 7 Jun 1996, R.García & F.Jiménez 6399 (F, S, USD);
- Sierra de Bahoruco, 19 km al NW del poblado Higüero, W del lugar que llaman El Tunal camino a Los Jobitos, 18°3.5'N, 71°25'W, alt. 450 m, 8 Jun 1993, R.García, F.Jiménez, G.Caminero, & D.Höner 4850 (F, NY). Provincia Pedernales:
- 22 km al W de Oviedo, en el Papayo, lado sur de la carretera Oviedo-Pedernales, 17°51'N, 71°31'W, alt. 140 m, 30 May 1997,R.García & D.Castillo 6573 (F, S, USD);
- Penisula de Barahona, Isla Beata, 1.5 km al SE del Campamento de la Marina de Guerra, 17° 36'N 71° 31.5'W, alt. 30 m, 30 Aug 1985, R.García & J.Pimentel 525 (NY);
- 17 km al O de Oviedo,lado S en la carretera Pedernales, alt. 140 m, 13 Mar 1997, R.García & R.Pujols 6544 (USD).