Cordia macvaughii is an uncommon species of section Cerdanae and is known only from the western Mexican states of Jalisco and Michoacan. It differs from other species in the section in having a large paniculate inflorescence covered with a downy-velutinous indument and corolla lobes that are wider than long. In the process of examining collections of Cordia for a revision of the genus in Mexico and Central America (Miller 1985), three collections were found to be distinct from all known species in section Cerdanae. All three of these novel collections were made by Professor Rogers McVaugh and it gives me great pleasure to name this attractive new species, C. macvaughii, in his honor. Cordia section Cerdanae is characterized by a unique type of fruit that is dry, single seeded, thin walled, and capped by the cartilaginous base of the persistent style. The corolla is marcescent and the entire flower persists, little changed in form, until wind dispersed. The most recent treatment of the species of Cordia section Cerdanae in Mexico and Central America is that of Ivan Johnston (1950) in which he recognized 13 species. He treated the group as section Gerascanthus, but an earlier name, section Cerdanae Roemer and Schultes, has priority. Of the species in western Mexico, the majority have very restricted distributions and are usually known from only a few localities. This seems to be true of C. macvaughii as well, which is known only from three collections from Jalisco and Michoacan. During January and February of 1982 and 1983 I was unable to locate this rare species at the localities where it had been previously collected. All species in this section are quite showy when flowering, but this occurs over a very short period of time and entire populations flower synchronously. I am publishing this name in advance of the revision for the genus in the hope that workers in this region may locate additional populations. Cordia macvaughii James S. Miller, sp. nov. (fig. 1).-TYPE: Mexico, Jalisco, steep hillsides west of Magdalena, 15 km above Plan de Barranca, with Acacia, Bursera, elev. 1250 m, 8 April 1965, Rogers McVaugh 23505 (holotype: MICH!). Arbor ad 10 m alta; folia decidua; petioli 1.82.6 cm longi, supra caniculati; lamina elliptica ad late elliptica, ad 14 cm longa, infra puberula; inflorescentia terminalis, paniculata, velutina. Flores heterostyli; calyx tubularis, 7-10 mm longus, cum 5 dentibus acuminatis, 0.5-1 mm longis, manifeste 10-costatus; corolla marcescens, alba, 5-lobata, lobis maxime late ovatis ad late depresso ovatis; stamina 5, filamentis pubescentibus; pariete fructus fibroso. Tree 6-10 m tall, twigs glabrous. Leaves deciduous; petioles 1.8-2.6 cm long, broadly sulcate on the adaxial surface, puberulent; blade elliptic to widely elliptic, 13.3-13.9 cm long, 6.6-10.4 cm wide, apex obtuse to rounded, base obtuse to acute, margin entire, upper surface glabrous to strigillose, lower surface densely puberulent. Inflorescence terminal, paniculate, 15-22 cm broad, usually with 200 or more flowers, branches downy-velutinous. Flowers distylous, the pedicels 1.2 mm long; calyx tubular, 7-10 mm long, 2.5-4.0 mm wide at the mouth, prominently 10-ribbed, velutinous, nearly truncate, with 5 acuminate teeth 0.5-1.0 mm long; corolla marcescent, white, funnelform, 1823 mm long, 5-lobed, the lobes very widely ovate to widely depressed ovate, 6-7 mm long, 6-9 mm wide, the tube 8-11 mm long; stamens 5, filaments 11-21 mm long, the upper 5.5-11 mm free, thickened, and pubescent just above the point of insertion, anthers oblong, 2-3 mm long; ovary cylindrical, 1 mm long, 1 mm broad, glabrous; disc very widely obovoid, 1 mm tall, 1 mm broad, glabrous; style 10.5-17.0 mm long, stylar branches 1.0-2.5 mm long, stigma lobes clavate; fruit enclosed by the persistent calyx