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Name

Vachellia daemon (Ekman & Urban in Urban) Seigler & Ebinger, Phytologia  87:  155.  2005.
syn.  Acacia daemon Ekman & Urban in Urban, Symb. antill. 9:  438.  1928.

Synonymy and types

Basionym:  Acacia daemon Ekman & Urb. in Urb., Symb. antill.  9: 438.  1928.  Feracacia daemon (Ekman & Urb.) Britton & Rose  N. Amer. Fl.  23: 86.  1928. - TYPE:  CUBA.  MATANZAS:  prope Ceiba Mocha in cuabales ad Canasi versus locis valde sterilibus, 1 Mar 1924, E. L. Ekman 18591 (holotype:  S;  isotypes: A, F, G, HAC photo, ILL, K, NY, US).

Formal description

Large shrub or small tree to 6 m tall.  Bark dark brown to reddish brown to gray, rough; the older branches and base of trunk bearing clusters of fusiform, straight to slightly curved stipular spines to 120 mm long clustered on short shoots.  Twigs gray to dark reddish-brown, not flexuous, glabrous.  Short shoots commonly present above the stipular spines, to 2 mm long, covered with acuminate stipules and old leaf bases, sometimes developing into normal shoots.  Leaves alternate, also commonly clustered on the short shoots, 0.4-3.2 mm long.  Stipular spines reddish-brown, becoming gray with age, symmetrical, terete, straight, aciculate to 42 x 0.9 mm near the base, mostly glabrous.  Petiole adaxially grooved, 0.4-3.2 mm long, glabrous; petiolar gland solitary, located just below the pinna pair, sessile to subsessile, apex circular to elliptical, 0.3-0.8 mm across, glabrous, depressed.  Rachis absent.  Pinnae 1 pair per leaf, 8-26 mm long. Petiolules 0.6-1.5 mm long.  Leaflets 10 to 30 pairs per pinna, opposite, 0.6-1.2 mm between leaflets, linear to oblong, 2.5-6.2 x 0.6-1.3 mm, glabrous, lateral veins not obvious, only one vein from the base, coriaceous, base oblique, margins not ciliate, apex obtuse.  Inflorescence a densely flowered globose head, 4.7-6.5 mm across, in fascicles of 1 to 4 from the short shoots.  Peduncles 10-18 x 0.4-0.6 mm, glabrous.  Involucre 4- to 5-lobed, located near the middle of the peduncle, glabrous, persistent.  Floral bracts spatulate, 0.3-0.6 mm long, sparsely puberulent, deciduous.  Flowers sessile, yellow; calyx 5-lobed, 0.7-1.0 mm long, glabrous; corolla 5-lobed, 1.4-1.7 mm long, glabrous; stamens about 60, stamen filaments 2.6-3.3 mm long, distinct; ovary glabrous, on a stipe to 0.3 mm long.  Legumes dark reddish-brown, straight to slightly curved, terete in cross section, strongly constricted between the seeds, linear, 90-110 x 4-6 mm, coriaceous, not striate, glabrous and lustrous, eglandular, dehiscent along the ventral suture; stipe 4-6 mm long; apex narrowing to an elongated beak to 8 mm long with a blunt tip.  Seeds uniseriate, surrounded by a reddish-brown pulp, light to dark brown, ellipsoid, slightly flattened, 4.3-5.2 x 2.7-3.2 mm, smooth; pleurogram oval, 1.5-2.1 mm across.  Flowers in March.  Chromosome number unknown.

Distribution

Restricted to arid, serpentine areas below 400 m in elevation in Camagüey, Guantánamo, La Habana, Holguín, La Villas and Matanzas Provinces, Cuba.  In addition to the areas listed below, Berazaín Iturralde (1986) reported the occurrence of Acacia daemon from near Camarioca, Matanzas Province, and Motembo and Santa Clara, Villa Clara Province.

Additional info

Vachellia daemon is a wide-ranging serpentine endemic found over a large area of Cuba.  This species is readily distinguished from other members of the V. acuifera group by a combination of characters:  mostly short petioles, involucre bracts near the middle of the peduncle, the sessile to subsessile petiolar gland, and the single pair of pinnae per leaf with most pinnae having 13 or more leaflet pairs.  The occurence of members of this taxon as a number of small, geographically isolated populations might be expected to have caused a high level of infraspecific variation, but such variation was found to be minimal.  The stipular spines, although usually longer than 12 mm, rarely are only 3-5 mm long; petioles are normally less than 1.5 mm long, but rarely are to 3.2 mm long; and the pinnae are usually 8-20 mm long, but some were to 26 mm long. The linear fruits of A. daemon unite this species with V. acuifera, V. barahonensis, and V. bucheri, although the involucral bract near the middle of the peduncle is a feature it shares only with V. zapatensis.  Vachellia daemon flowers typically have as many as 60 stamens, 50 being the upper limit of the other species of the V. acuifera group.  Of the 14 specimens tested, none were found to be cyanogenic, even after the addition of emulsin.

Holes in the stipular spines made by ants were found in two collections, E.L.Ekman 18951, and A.Álvarez et al. 28923.  Berazaín Iturralde and Rodríguez Soria (1983) found four species of ants associated with the stipular spines of V. daemon; no plant vouchers were cited.  Rarely, the spines of V. tortuosa (Clarke et al. 1989), V. rigidula (Seigler et al. 1982), and V. caven also have been found to be inhabited by ants.  This loose ant interaction now appears to be a general, if rare, association within the New World members of Vachellia (Acacia subgenus Acacia, series Gummiferae), and unrelated, except perhaps as a preadaptation, to the obligate mutualism found in the ant-acacias (Seigler and Ebinger 1995).

Vachellia daemon has been cited by Berazaín Iturralde (1981), along with V. bucheri, as an example of a vicariant distribution of serpentine-adapted plants between eastern and western Cuba.  Berazaín Iturralde (1976, 1986), Iturralde Vinent (1982), and Méndez et al. (1988) assert that the serpentine areas of eastern Cuba (Moa, Baracoa, and Nipe) and, to a lesser extent, western Cuba (Cajalbana) constitute centers of origin for serpentine-adapted taxa in Cuba.  These areas have a much higher diversity of endemic taxa than serpentine areas in central Cuba, and are the only areas in Cuba that were not submerged during the Middle Tertiary.  This has led to the development of a model of evolution for these taxa that proposes migration primarily from east to west as newly emerged serpentine areas in central Cuba became colonized, while a secondary migration occurred in the reverse direction (Berazaín Iturralde 1981, Borhidi 1991).

Although possibly an important source for other groups, Cajalbana in far western Cuba is probably not an important center of origin for serpentine-adapted acacias because none currently inhabit this area, although they may have in the past.  Also, the habitat is much different than serpentine areas in the rest of Cuba, being comprised of a pine savanna on deep lateritic soils.  The occurrence of V. daemon in Oriente (Holguín) Province at sites very near those of V. bucheri leaves the above model in a confused state.  Although the occurrence of V. daemon may still possibly be explained by its arising in isolation in western Cuba with dispersal eastward, it may also have arisen in eastern Cuba in response to another, as yet undetermined, isolating mechanism.

Representative specimens

CUBA:

Camagüey Province:

Guantánamo Province:

La Habana Province:

Holguín Province:

Matanzas Province:

Villa Clara Province:

 

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