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Name

Vachellia mayana (Lundell) Seigler & Ebinger, Phytologia 87:  163.  2005.
syn. Acacia mayana Lundell, Publ. Carnegie Inst. Wash. 478:  210.  1937.

Synonymy and types

Basionym:  Acacia mayana Lundell, Publ. Carnegie Inst. Wash.  478: 210.  1937. - TYPE:  GUATEMALA.  EL PETÉN:  near San Diego on the Rio Pasión, 10 Apr 1935, M. Aguilar H. 495 (holotype:  MICH, isotypes:  GH, NY, US).

Formal description

Shrub or small tree to 10 m tall.  Bark not seen.  Twigs gray to light brown, not flexuous, glabrous.  Short shoots absent.  Leaves alternate, 150-400 mm long.  Stipular spines dark black, symmetrical, elliptical in cross section and with two blade-like longitudinal flanges extending from the base to the apex along each margin; strongly reflexed, stout and inflated, 30-75 x 5-12 mm near the base, glabrous.  Petiole adaxially grooved, 15-35 mm long, glabrous to puberulent; petiolar gland 1(2), located just below the first pinna pair, sessile, canoe-shaped, base 1.5-6 mm long, apex elongated, 1.2-5 mm long, glabrous and strongly striate.  Rachis adaxially grooved, 130-380 mm long, glabrous to puberulent, a sessile, canoe-shaped gland present between each pinna pair.  Pinnae 6 to 19 pairs per leaf, 75-120 mm long, 15-30 mm between pinna pairs.  Petiolules 1.4-2.5 mm long.  Leaflets 25 to 40 pairs per pinna, opposite, 1.6-3.0 mm between leaflets, linear, 10-23 x 1.8-3.5 mm, glabrous, lateral veins obvious, 3 to 5 veins from the base, base oblique, margins usually not ciliate, apex obtuse; beltian bodies 1.3-1.9 mm long.  Inflorescence a densely flowered spike that narrows toward the elongated and pointed apex, 30-50 x 7-10 mm near the base, solitary or in short, leafless racemose clusters.  Peduncles 5-15 x 4-6 mm, glabrous.  Involucre 4- to 5- irregular, shallow lobes, located near the base of the peduncle, glabrous to lightly puberulent, persistent.  Floral bracts peltate, 0.9-1.2 mm long, apex circular and glabrous, deciduous.  Flowers sessile, pinkish; calyx 5-lobed, 0.9-1.2 mm long, glabrous; corolla 5-lobed, 1-1.3 mm long, slightly longer than the calyx, glabrous; stamen filaments 0.6-1.6 mm long, distinct; ovary glabrous, sessile.  Legume dark reddish brown, slightly curved, nearly terete in cross section, not constricted between the seeds, oblong, 90-120 x 12-15 mm, coriaceous, reticulately striate, glabrous, eglandular, indehiscent; stipe to 25 mm long; apex narrowing to a long spine-like beak 7-20 mm long.  Seeds uniseriate, imbedded in a white pulp, dark brown, ovoid, slightly flattened, 10.0-11.5 x 6.0-7.5 mm, smooth; pleurogram oblong to U-shaped, 2.8-4.5 mm across. Flowers in January to June. Chromosome number:  Not determined.

Distribution

Apparently a species of lowland, wet forests and forest margins in the departments of Alta Verapaz and El Petén, Guatemala, and the states of Chiapas, Oaxaca, Tabasco, and Veracruz, Mexico (Janzen 1974).

Additional info

According to Janzen (1974), Vachellia mayana probably represents a "wet-forest edition" of V. cornigera.  Undoubtedly, the two taxa are very closely related, having many vegetative and floral characteristics in common. However, the large leaflets (more than 10 mm long), the rachis glands between each pinna pair, and the inflorescence, which narrows toward the elongated and pointed apex, separate this species from the closely related V. cornigera and V. sphaerocephala.  Also, the pair of blade-like longitudinal flanges extending from the spine base to apex separates V. mayana from all other species of ant-acacia.  As is typical of most ant-acacias, none of the individuals of V. mayana tested positive for cyanide production.

Vachellia mayana is one of the rarer of the ant-acacias.  Collecting data from the few collections observed indicate that it has pinkish flowers and varies in size from a shrub to a small tree to 10 m tall.  Most collections indicate that Vachellia mayana occurs as widely scattered individuals in moist lowland forests.  Janzen (1974) reported an individual from an old second growth cornfield regeneration where the forest was about 15 m tall.

Unlike most wet forest ant-acacias, Beltian body production in Vachellia mayana is extremely high. On developing leaves, nearly all of the leaflets contain Beltian bodies, and these bodies are usually about 2 mm long and up to 0.8 mm wide.

Flowering time

January-June.

Representative specimens

GUATEMALA:

Alta Verapaz:

El Petén:

MEXICO:

Chiapas:

Oaxaca:

Tabasco:

Veracruz:

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