A new species of morning glory from southwestern Mexico, Ipomoea cuprinacoma (Convolvulaceae), is described. The species is assigned to Ipomoea series Arborescentes with other stout lianas and trees, and distinguished from I. populina on the basis of slender stems, canescent peduncles and leaf blades, exclusively axial inflorescences, and long, pale-coppery seed hairs.
Ongoing plant collection programs of the Instituto de Ecología in Pátzacuaro, Mexico, continue to uncover new species from southwestern Mexico. A morning glory that ranges from J alisco to eastern Guerrero, Ipomoea cuprinacoma E. Carranza & J.A. McDonald, is described herein and allied with I. populina House, a common liana of Ipomoea series Arborescentes ( Choisy) D.F. Austin.
Ipomoea cuprinacoma E. Carranza & J.A. McDonald, sp. nov. (Fig. 1).
Type: MEXICO. MICHOÁCAN: Mpio. Penjamillo, 2 km W of Penjamillo, E. Carranza G. 5608 (Holotype: IEB; Isotypes: ENCB, MEXU, TEX.)
Ipomoea populina House primo adspectu maxime simili, sed caulibus apicem versus gracilibus, 1–2 mm latis, canis, laminis infra canis vel dense puberulis, sepalis inaequalibus, coma cuprina seminibus differt.
Lianas twining, trailing, robust; stems ligneous, branching, 2–14 m long, to 5–7 cm wide at base, 1–2 mm at tips, new growth canescent, old growth glabrous or scarcely pubescent, striate, sparingly papillose. Leaves simple, petiolate; petioles 2.6–11 cm long, 1–2 mm in diameter, tomentose, tomentulose or sparsely pubescent; blades ovate or ovate-elongate, (4.5-) 7–14 (-19) cm long, 4.0–10.5 cm wide, entire, acuminate at apex, truncate or cordate at base, chartaceous, green and densely to sparsely pilose above, canescent or densely pilose below, the hairs simple, T-shaped, 3 or 4-branched. Cymes axillary, simple, mono- or dichasial, flowers 1–5; peduncles 0.3–5.5 cm long, 1–2 mm in diameter, smooth or striate, canescent during inception, becoming glabrous and lignescent during anthesis and fruition, secondary peduncles 0.3–1.2 cm long, 1–2 mm in diameter; pedicels 0.5–2.5 cm long, 1–2 mm in diameter during anthesis, elongating and thickening somewhat (ca. 3 mm in diameter) during fruition, canescent during inception, becoming glabrous during anthesis and fruition. Flowers diurnal; sepals unequal, persistent in fruit, ovate or broadly elliptic, outer 5.5–8 mm long, 4–6 mm wide, inner 8–12 mm long, 6–9 mm wide, with apex obtuse or truncate, glabrous, coriaceous, and with margins entire, scarious; corolla infundibular, 5.5–8 cm long, tube 3.5–5.0 cm long, the base constricted, 6–8 mm in diameter, the throat 1.8–2.5 cm in diameter (in a pressed condition), white with a broad purple collar inside, glabrous, limb white, slightly 10-lobate, plical zones glabrous, interplical zones sparingly pubescent; stamens unequal, included, 1.6–3.l cm long, basally pubescent; style 3.4–4.2 cm long, glabrous; stigma subglobose, bilobate. FRUIT a broadly ellipsoid capsule, 1–1. 7 (-2) mm long, 0.8–1.2 cm wide, 2-locular, 4-valvate, drying brown, lignescent, glabrous, the base of style persistent on apex until dehiscence; seeds ( 4)7–12 mm long, ellipsoid-triangulate, glabrous, brown, bearing long hairs on outer margins, comas 1–1.4 cm long, shiny, pale brown or copper.
Additional Specimens Examined: MEXICO. Guerrero. Km 98.3 on Hwy. 51 from Iguala to Arcelia, ca. 2 km W of Las Ceibitas, 1150 m, 2 Oct 1982, H. fltis, B. Benz & M. Burd 28692 (IEB, TEX). Jalisco: Mpio. Guadalajara, Barranca of Huetitán, below Guadalajara Zoological Park, 1450 m, 4 Jul 1990, M. Cházaro, J. J. Guerrero & S. Carvajal 6265 (IEB, TEX); Mpio. Guadalajara, Barranca of Huetitán, below Guadalajara Zoological Park, 1400 m, 21 Aug 1990, M. Cházaro & J.J. Guerrero 6377 (IEB, TEX); Mpio. Jocotepec, 3 km S of Zapotitán de Hidalgo, 1880 m, 1 Jun 1986, J.A. Machuca & S. Carvajal 1467 (IEB, TEX), Mpio. Jocotepec, NW of Zapotitán in Arroyo de Huariche, 1800 m, 25 Aug 1991, J.A. Machuca 6722 (IEB, TEX); Mpio. Jocotepec, Barranca de Sayula, W of San Pedro Tesistán, 1450 m, 5 Jul 1992, Machuca 6882 (IEB, TEX); Mpio. Jocotepec, Barranca de Sayula, W of San Pedro Tesistán, 1750 m, 18 Jun 1995, J.A. Machuca 7320 (IEB); Sierra La Difunta, trail to Las Lajas, S of Tepatitlán, 1600 m, 21 Aug 1994, J.A. Machuca 7220 (IEB); Mpio. Zapopan, 0.5 km S of Hacienda del Lazo, 1050 m, 31 Jul 2001, Carrillo-Reyes 2319 (IEB); Mpio. Mascota, Km 1 on road from Mascota to Juanacatlán, 1430 m, 12 Aug 2001, Carillo et al. 2497 (IEB). MICHOACÁN: Mpio. Churintzio, Los Palos Amarillos Canyon, Sanguijuelas, Labat 1834 (IEB); Mpio. Penjamillo, 2 km W of Penjamillo, E. Carranza et al. 5790 (IEB); E. Carranza & Silva 5028a (IEB); Penjamillo, by banana plantation, Diaz-Barriga & Perez 7242 (IEB).
Ipomoea cuprinacoma fits comfortably within Ipomoea series Arborescentes, in the company of other Mexican lianas and arborescent morning glories. Most members of this distinctive group are trees (McPherson, 1981), several of which occur as dominant elements in tropical deciduous forests of southern Mexico (i.e., I. pauciftora Mart. & Galeotti, I. murcoides Roem. & Schult., and I. wolcottiana Rose). Anatomical and phylogenetic analyses of this distinctive group reveal that arborescent growth habits are derived in the genus (McDonald, 1991, 1992; McDonald and Mabry, 1992), suggesting that I. cuprinacoma and other lianas of the complex, such as I. populina and I. praecana House, may represent ancestral members of the group. The new species is most similar to I. populina on the basis of its thickened basal stems to 7 cm diameter, ovate leaves, simple axillary cymes, glabrous sepals, white corollas with purple-pigmented tubes, and ellipsoid-triangulate seeds that present long hairs along their outer margins. The new species is distinguished from I. populina, however, by slender incipient stems (1–2 mm in diameter), leaf blades that are canescent or densely sericeous below, canescent primordial peduncles and pedicels, and exclusively axial inflorescences (Fig. 1). Seed hairs of the new species are also distinguished by their palecoppery sheen, hence the species epithet, cuprinacoma (‘copper-colored hair’). In contrast, new stem growth of I. populina is more fleshy and robust, the tips from 2–4 mm in diameter, and maintaining a chlorophyllous, glabrous or glabrescent condition. Ipomoea populina also presents laminas that are glabrous or only sparingly pubescent above and below, incipient peduncles and pedicels that are glabrous or sparingly pubsecent (never canescent), flowers that are born terminally and in leaf axils, and white seed hairs.
As presently known, Ipomoea cuprina coma occurs sporadically from Jalisco to western Guerrero (Fig. 2). The southernmost limits of the new species approach the western-most limits of I. populina, the latter of which ranges from western Guerrero to Nicaragua (McPherson, 1981). Ipomoea cuprinacoma is found in mountainous habitats from 1000–1900 m, and usually occupies tropical deciduous forests that are dominated by Acacia, Bursera, Ceiba, Cordia, Heliocarpus, and Lysiloma, or tropical deciduous oak forests that are ecotonal with this vegetation type.
The authors express gratitude to Ms. Susan Vaclavik for preparing the illustrations.