A new species of Olacaceae from Amazonian Peru is described as Aptandra caudata. Aptandra caudata A. Gentry & Ortiz, sp. nov. TYPE: Peru. Loreto: Provincia Maynas, Quebrada Sucusari, N bank of Rio Napo below Mazan, mature upland forest on lateritic soil, elev. 130 m, 3?15'S, 72?55'W, 7 July 1983 (fl), Gentry, Vasquez & Jaramillo 42718 (holotype, MO; isotypes, AMAZ, USM). Figure 1. Arbor parva, ramulis teretibus, glabris. Folia anguste elliptica vel elliptico-oblonga, apice abrupte per 1.5-3.5 cm caudata, glabra, membranacea. Inflorescentia pauciflora, pedicellis filiformibus, 1-1.5 mm longis. Flores in alabastro cylindrici, ca. 5 mm longi; calyce obtuse 4lobulatos, 0.5 mm longo. Fructus globosus, ca. 2.5 cm diametro, calyce subpatelliformi expanso subtensus. Treelet 3-5 m tall; branchlets slender, subterete, smooth, glabrous. Leaves narrowly elliptic or ellipticoblong, the apex abruptly caudate-acuminate for 1.5-3.5 cm, the base ? cuneate, membranaceous, olive green when dry, glabrous, 3.5-15 cm long (excluding drip tip), 1.2-4.5 cm wide, the lateral nerves 6-14 pairs; petiole slender, 4-8 mm long, ca. 1 mm thick. Inflorescence an open axillary panicle, few-flowered, the branches slender, the peduncle ca. 1 cm long, the flowers arranged in 2-3flowered umbels at ends of the inflorescence branches, the filiform pedicels ca. 1-1.5 cm long. Flower bud a cylindrical tube with globose apex; calyx shallowly and obtusely 4-lobed, ca. 5 mm long at anthesis, much enlarged in fruit; petals 4, linear below, somewhat broadened at apex, greenish cream, ca. 5 x 1 mm, forming a strictly cylindrical tube with a globose apex; stamens 4, the filaments connate into 4-mm-long tube, the anthers ca. 0.5 mm long, fused to an annulus, opening by a thin reflexing valve; pistil ca. 4 mm long, the slender style apically thickened at level of anthers. Fruit globose, singleseeded, green, ca. 2.5 cm diam., the fruiting calyx coriaceous, becoming broadly cup-shaped to almost patelliform, enveloping less than the basal quarter of drupe; seed globose, ca. 7 mm across. Distribution. Known only from the type locality at the Explornapo Camp on the Rio Sucusari in Loreto Department, Peru, 116-130 m elevation. Additional collections examined. PERU. LORETO: (all from type locality), 5 July 1983 (fl), Gentry et al. 42628 (AMAZ, MO, USM), 14 June 1986 (st), Gentry et al. 54321 (AMAZ, MO), 7 Oct. 1986 (st), Vasquez & Jaramillo 8156 (AMAZ, MO), 7 Nov. 1989 (fr), Vasquez & Jaramillo 13103 (AMAZ, MO, USM). Only three species of Aptandra were recognized by Sleumer (1984), two in the Neotropics and one in tropical Africa. Of these, A. caudata is closest to A. tubicina (Poeppig) Benth. ex Miers, which also occurs in Amazonian Peru, on account of the membranaceous, cuneate leaves and strictly cylindric pre-anthesis corolla tube. The most striking differentiating feature of A. caudata is the conspicuously caudate leaf apex, especially pronounced in small leaves where a 3-cm-long leaf can have a 1.5-cm-long drip tip. In contrast, A. tubicina is acuminate with the drip tip 0.5-1.5 cm long. The leaves of A. caudata are also narrower and more elliptic than in A. tubicina; although the latter sometimes has some leaves as narrow as those of A. caudata, the narrower leaves are mostly lanceolate. The flower of A. caudata is also noticeably longer (5 mm vs. 3 mm) than that of A. tubicina and has a more prominently globose bud apex and more shallowly and obtusely lobed calyx. Another difference is the almost patelliform fruiting calyx of A. caudata, which covers only the extreme base of the drupe and is very different from the broadly cupular calyx of A. tubicina, which covers most of the lower half of the drupe. It is possible that two species are included in Sleumer's (1984) concept of A. tubicina: one with membranaceous to chartaceous, strongly acuminate leaves, which includes the type; the other with more subcoriaceous, subacuminate leaves and smaller, more numerous flowers, which is much more common, at least in Amazonian Peru. Aptandra caudata is vegetatively more similar to the Brazilian type material of A. tubicina than to the rest of the Peruvian material. However, A. caudata cannot be conspecific with either variant of A. tubicina because of the differences in size and shape of flowers and buds and the patelliform fruiting calyx. Aptandra caudata is the largest-flowered species in the genus and approaches Chaunochiton in flower size and in the almost patelliformly expanded fruiting NOVON 2: 153-154. 1992. This content downloaded from 207.46.13.172 on Tue, 23 Aug 2016 04:10:19 UTC All use subject to http://about.jstor.org/terms