Calycogonium bairdianum Skean, Judd, Clase & Peguero

Authority

Skean, James D., Jr., et al. 2010. (Melastomataceae: Miconieae), a new species from the Cordillera Central, Dominican Republic. Brittonia. 62 (3): 210-214.

Family

Melastomataceae

Scientific Name

Calycogonium bairdianum Skean, Judd, Clase & Peguero

Description

Description - Evergreen shrub or small tree to 5 m tall. Indumentum sparse, of multicellular, minute brown globular hairs to 0. 12 mm across, pale to brownish globular-stellate hairs to 0.25 mm across, and stouter, multiseriate, mostly unbranched hairs to ca. 1.7 mm long. Young twigs green or tinged with red-purple, slightly quadrangular, becoming more rounded with age, 1.5 -2.5 mm in diameter, glabrous to very sparsely pubescent on youngest portions with globular - stellate hairs; internodes 1.1 - 3.6 cm long(to 11.5 cm long in sterile shoors). Leaves opposite, with petiole 4-11 mm long, glabrate to sparsely pubescent with globular - stellate hairs on youngest leaves; blade (2.9-)4.5-8.1 x(1.0-)1.4 -2.8 cm, narrowly ovate or elliptic, less commonly obovate, flat often drying green above and brownish below, the apex acuste or obtuse, less commonly slightly acuminate, the base acute or slightly cuneate, the margin plane to slightly revolute, especially near base, entire or slightly undulate in distal 1/3; venation acrodromous, suprabasal, with 3 conspicuous longitudinal veins, the midvein and 2 secondary veins, the secondary veins typically intersecting the midvein 3-9 mm above the base of the blade and placed 0.5- 2mm in from margin at the blade's widest point, and percurrent tertiary veins oriented subperpendicular to midvein, the higher order veins obscure, ± reticulate, the smallest reticulations not complete; adaxial surface green when fresh, the indumentum initially of sparse, globular - stellate hairs, but very quickly glabrescent, although a few globular - stellate hairs sometimes retained on lower portion of the midvein, the three longitudinal veins (midvein and 2 secondaries) flat to slightly impressed, the percurrent tertiary veins flat when dry, but sometimes slightly impressed in living material; abaxial surface pale green when fresh, dotted with minute globular hairs with scattered sparse globular stellate hairs on the veins, the midvein conspicuously raised, the 2 conspicuously raised, the 2 conspicuous secondary veins slightly raised flat, the tertiary veins flat but visible, the higher order veins ± obscure; 2 acarodomatia formed by unbranched to slightly branched multiseriate hairs to 1.7 mm long at the junction of the midvein and 2 largest secondary veins. Inflorescenses terminal, typically 3- flowered dichasium, sessile, paried bracts ovate, ca. 3.0 x 0.6 mm, the flowers each with a pair of narrowly ovate bracteoles ca. 0.6 x 0.3 mm. Flowers 4- merous, slightly zygomorphic, the pedicel to 1mm long. Hypanthium green or tinged with red- purple, rounded in cross section, 2.6-3.5 x 1.9 -2.5 mm, the outer surface glabrous or with some scattered globular-stellate hairs near the base, the inner surface glabrous and smooth. External calyx lobes 4, 1.9 -2.5 mm long(as measured from teh adaxial point of attachment at apex of internal calyx lobe to apex of tooth), flattened at right angles to floral radii, thus parallel to and ± obscuring the shorter internal lobes, and triangular when viewed abaxially (and 1.1 -1.9 mm across, when measured at the apex of the internal caylx lobe), with obtuse or acute apex, glabrous or with sparse globular - stellate hairs. Internal calyx lobes 4, inconspicuous ca. 1 x 1mm, broadly triangular, glabrous, with obtuse apex; calyx tube ca. 1.1 mm long. Petals 4, 4.5 -5.4 x 1.9 - 2.0 mm, narrowly obovate and asymmetrical, glabrous, pink to red, each with a narrowly triangular, often slightly falcate, terminal projection 1.7 -1.9 x 0.7 - 0.8 mm, the apex acute; margin with 1-2 teeth, otherwise entire. Stamens 8, glabrous, ± arranged raidally around the style at anthesis, cream - colored, drying brown, filament ca. 3.0 x0.4 mm, narrowly obovate, flattened; anther ca. 2.0 x 1.0 mm narrowly ovate, straight, dehiscing by a small apical pore. Ovary 4-loculate, fully inferior, ca. 2.5 x 1.5 mm, cylindrical, apically glabrous, unridged, with axile placentation, the ovules numerous, borne on expanded placenta that extends into each locule; style straight to slightly curved, terete, 4.5 -4.7 mm long, ca. 0.4mm wide, glabrous, arising from the ± flat apex of the ovary;s tigma truncate, minutely papillose. Immature berries ca. 7 x 3 mm, cylindrical, green or tinged with red, probably turning purple-black when fully mature, glabrous. Mature fruits and seeds not observed.

Discussion

Distribution and ecology: Hispaniola (Dominican Republic), Cordillera Central; along the banks of rivers in moist pine forests; 525-990 m. Associated with species include Pinus occidentalis Sw., Calyptronoma sp., Clusia rosea Jacq., Cyrilla racemiflora L., Eugenia domingensis O. Berg, Lyonia truncata Urb., Mecranium acuminatum (DC.) Skean, Piper aduncum L., Psidium guajava L., and Syzygium jambos (L.) Alston.

Phenology. - The flowering period is poorly known; the species has been collected in flower or with very young fruits in May, July, and August. It has not been collected with mature berries.

Etymology. - The specific epithet honors Richard L. Baird (1956-), former Chair of the Albion College Board of Trustees, who led a capital campaign that has resulted in a reno- vated and expanded LEED Silver-certified science complex, which was dedicated in 2007.

Calycogonium bairdianum is a Hispaniolan endemic known only from the Cordillera Central. It is phenetically very similar to a group of glabrate species that is characterized by hair-tuft acarodomatia (see Judd & Skean, 1991, Fig. lb, although in some members of the group the hairs tend to be ± connate, forming a brownish conical structure, see Fig. la) and flowers with short pedicels and hypanthia that are circular in cross section. Other members of this group include Calyco- gonium glabratum (Sw.) DC, C impressum Urb. & Ekman, C. rhomboideum Urb. & Ekman, and C torbecianum Urb. & Ekman. Of these, Calycogonium impressum, a rare species that occurs in higher elevation (1250- 1500 m) pine forests of the Cordillera Cordillera, has leaves that are shaped most similarly. Calycogonium bairdianum can be distinguished easily from C impressum by being relatively glabrous (vs. pubescent) and having larger leaves, i.e., (2.9-)4.5-8.1 cm long (vs. 2.1-3.7 cm long in C impressum) with veins that are plane to slightly impressed above (vs. more strongly impressed above).

In the key prepared by Liogier (2000), Calycogonium bairdianum would be identi- fied as C rhamnoideum Naud., a species reported from Cuba, Hispaniola, and Jamaica (Alain, 1957; Liogier, 2000; Proctor, 1972). Calycogonium rhamnoideum has longer external calyx teeth (to 4 mm long vs. to 2.5 mm long in C bairdianum). In addition, C. rhamnoideum has acarodomatia that are formed by connate hairs that form scale-like structures, unlike the simple tufts of hairs found in the acarodomatia of C. bairdianum.

The discovery of Calycogonium bairdia- num brings the total number of Calycogo- nium species described from Hispaniola to 19, all endemic to the island (Liogier, 2000; Judd et al., 2008). With increasing evidence of polyphyly, the taxonomic fate of the genus is uncertain. It is hoped that future studies will clarify phylogenetic relationships and inform the taxonomy and nomenclature of these species.