A New Species of Gibsoniothamnus (Schlegeliaceae) from Costa Rica and Panama

Abstract

A new species, Gibsoniothamnus parvifolius, is described based on disjunct populations from Costa Rica and western Panama. The species is distinguished by its relatively small, acuminate leaves, few-flowered inflorescences, and its relatively small, purplish flowers borne on short pedicels. Gibsoniothamnus parvifolius Barringer, sp. nov. TYPE: Panama. Chiriquf: NE del campamento Fortuna, 1000-1200 m, 15 Aug. 1976, M. Correa, R. Dressler & Garibaldi 2500 (holotype, MO; isotypes, NY, PMA). Figure 1. A Gibsoniothamno epiphytico foliis minoribus anguste lanceolatis vel ovato-lanceolatis acuminatis coriaceis, floribus solitariis vel geminatis differt. Epiphytic shrub or small epiphytic tree to 4 m tall; young branches glabrous to sparsely pubescent, terete to slightly angled; older stems with gray-brown bark and persistent raised petiole bases. Leaves opposite, anisophyllous; larger leaves with petioles 3-7 mm long, the lamina narrowly lanceolate to obovate-lanceolate, 3-5.5 cm long, 1.0-1.8 cm wide, coriaceous, glabrous or rarely pubescent, gland-dotted, the base cuneate, the apex acuminate to long-acuminate, the veins immersed above, prominent and often reddish below, 2 or 3 secondary veins per side, the upper surface dark green, shiny, the lower surface light green, dull, domatia present in the axils of the secondary veins; smaller leaves with petioles 2-5 mm long, the lamina ovate-lanceolate, 1.6-2.2 cm long, 0.6-1.4 cm wide, coriaceous, glabrous or rarely pubescent, gland-dotted, the base rounded to acute, the apex rounded to obtuse, rarely acuminate, the veins impressed above, prominent and sometimes reddish below, 1-2 secondary veins per side. Flowers axillary, solitary or in pairs; pedicels 1.5-2.0 cm long, sparsely pubescent with glandular trichomes, slightly thickened above, bracteolate at base, the bracteoles linear, to 1 mm long; calyx campanulate, purple to red-purple, the tube 3-4 mm long, with 5 lobe-like enations that develop from the side of the calyx tube, the enations 8-9 mm long, 1 mm wide, narrowly triangular, slightly winged, glabrous, spreading; corolla cylindric, reddish violet to purple or lilac, 1.5-2.0 cm long, 3 mm diam., the upper lobes broadly ovate, 1.5-2.0 mm long, 2.0-2.5 mm wide, the lateral lobes ovate, 1.5-2.0 mm long, 1.5-2.0 mm wide, the median lobe ovate, 1.5-2.0 mm long, 2.0-2.5 mm wide, the lobes generally more darkly colored than the tube; stamens 4, attached about 5 mm above the base of the corolla tube, with a ring of trichomes at the level of attach ent, the filaments 12-16 mm long, filiform, curved above, slightly thickened at the base; staminode 1.7-5.0 mm long; pistil glabrous, ovary globose, 1 mm tall, glandular at the base, the style elongate, 15-18 mm long, the stigma clavate to capitate. Berry globose, to 1 cm diam., green turning white, with 5-10(-20) seeds, the seeds fusiform, 2.0-2.5 mm long 1.0-1.4 mm wide, with a loose, hyaline, reticulate seedcoat. Thi species is distinguished by its small leaves, slightly winged calyx with narrowly triangular enations, and few-flowered inflorescence. It is found growing on the volcanic mountains of Costa Rica and western Panama in two disjunct populations. The northern Costa Rican plants grow between 300 and 700 m, while the southern Costa Rican and Panamanian plants grow between 1000 and 1300 m elevation. The two populations differ slightly and may eventually prove to be distinct species. The northern plants tend to have terete, not angled, branches a d smaller staminodes, less than 3 mm long. The distribution of the northern populations overlaps slightly with that of Gibsoniothamnus epihyticus (Standley) L. O. Williams, native to central Cos a Rica, and the southern populations. Th s pecies is sometimes confused with Gibsoniothamnus epiphyticus, but the new species differs by its sm ller, narrowly lanceolate, acuminate, coriaceous leaves, and 1or 2-flowered inflorescence. In c ntra t, G. epiphyticus has elliptic, subcoriaceous l aves, 5.5-7.5 cm long, and flowers in condensed, p niculate inflorescences. The new species is also confused with G. alatus A. Gentry, but that sp cies has large calyx wings, usually extending more than 4 mm, leaves 4-9 cm long, and white flowers. Many of the specimens of G. parvifolius are NovoN 9: 476-478. 1999. This content downloaded from 157.55.39.144 on Wed, 07 Sep 2016 04:37:00 UTC All use subject to http://about.jstor.org/terms Volume 9, Number 4 1999 Barringer Gibsoniothamnus parvifolius 477