A new species of Roucheria and a new species of Hebepetalum (Hugoniaceae) from southern Venezuela are described and illustrated. Roucheria sipapoensis is a montane, small-leaved shrub known only from Cerro Sipapo in Amazonas state, while Hebepetalum neblinae is a lowland, wet forest tree from white sand areas in southernmost Venezuela and northern Brazil. Keys to the species of both genera are provided. Roucheria and Hebepetalum are closely related woody taxa in the Linales. Cronquist (1988) placed both genera in the Hugoniaceae, although they had earlier been treated in a more broadly circumscribed Linaceae (Planchon, 1847; Bentham, 1862). While preparing the Hugoniaceae treatment for the Flora of the Venezuelan Guayana (Ramirez et al., 1999) and undertaking a revisionary study of Hebepetalum and Roucheria, we discovered one new species in each genus. Venezuela is the center of diversity of these genera, with five species of Roucheria and all three species of Hebepetalum occurring there. The species commonly known as Roucheria punctata (Ducke) Ducke is now considered a synonym of an earlier name, R. columbiana Hallier (Ramirez et al., 1999). Cronquist's circumscription of Hugoniaceae is supported here based on results of revisionary work of these genera, which point to the presence of drupaceous fruit, woody habit, and crenulate/subcrenulate leaf margins with glands as supporting shared characters with the family. Hebepetalum is distinguished from Roucheria by its petals with a clawed base which are inwardly pubescent, the presence of trichomes of variable density at the apex of the ovary, and broquiodromous leaf venation with secondaries joined in a series of conspicuous and wellformed arches. In Roucheria the venation is camptodromous, with the secondary veins tightly parallel, and lacking the series of conspicuous arches. Both genera share a submarginal collecting (fimbrial) vein, which is formed by the fusion of the secondaries. The leaf venation in Roucheria is reminiscent of that of many members of the Clusiaceae and Ochnaceae. Including the species described below, we now recognize eight species in Roucheria and three in Hebepetalum. Roucheria sipapoensis Jardim & P. E. Berry, sp. nov. TYPE: Venezuela. Amazonas: Cerro Sipapo, Paraque, higher plateau, among rocks, 1798 m, 12 Dec. 1948, B. Maguire 27625 (holotype, MO; isotypes, NY, WIS). Figure 1. Haec species inter congeneros vegetative glabros Roucheriae monsalveae A. H. Gentry foliis subsessilibus decurrentibus etiam R. elatae Ducke inflorescentia ex panicula axillari 1-4 cm longa constante maxime accedit, sed a hac foliis valde coriaceis atque habitu humiliore altitudine 10 m non excedente, ab illa foliis plerumque minoribus in sicco griseo-olivaceis atque inflorescentia paniculata, ab ambabus lamina foliari marginibus ad basim valde revoluta distinguitur. Shrub or small tree 3-10 m tall; stems glabrous, nodes round. Leaves alternate, simple, ovate-elliptical, coriaceous, subsessile, olive-gray upon drying, with a thin layer of wax, 1.8-8.5 cm long, 0.52.5 cm wide, broadly acute at the apex, decurrent, with inrolled margins at the base, glabrous, dark green on the adaxial surface, light green abaxially; midvein raised abaxially, impressed adaxially, numerous strongly parallel secondary veins terminating at the margin in a submarginal, continuous collecting vein, raised on both surfaces; margins crenate-subserrate with numerous dentations, 4055 glands per leaf, inconspicuous, oval, present in each sinus between dentations and flush, not raised in sinus; petioles 0-4 mm long; stipules triangular, caducous, 0.7-0.9 mm long. Inflorescence axillary anicles grouped toward the branch apices, axis 14 cm long, canaliculate. Flowers regularly arranged on branches of inflorescence, each branch 1to several-flowered; bracteoles obovate, 1-1.5 mm NovoN 9: 520-523. 1999. This content downloaded from 207.46.13.97 on Thu, 08 Dec 2016 05:11:44 UTC All use subject to http://about.jstor.org/terms Volume 9, Number 4 1999 Jardim & Berry Hugoniaceae from Venezuelan Guayana 521 ,.., i .,.,c ... ~ 'I'