Monographs Details: Heteropterys ayacuchensis W.R.Anderson
Authority: Anderson, W. R. 1990. Two new species of Heteropterys (Malpighiaceae) from the Guayana Highland. Mem. New York Bot. Gard. 64: 225-228.
Family:Malpighiaceae
Description:Species Description - Frutex 1-2 m altus. Folia decussata; foliomm majo mm lamina 7-8.5 cm longa, 2-3 cm lata, plana, anguste ovata, basi late cuneata vel rotundata, apice anguste acuta vel acuminata, glabrata, reticulo utrinque visibili venulis quam nervis lateralibus subaequaliter prominentibus; petiolus 4-7 mm longus, plemmque in medio biglandulifer. Inflorescentia e pseudoracemis axillaribus, 3-8 cm longis, 8-14-floriferis constans, bracteis deciduis. Sepala per anthesin revoluta, utrinque sericea. Samara 17-20 mm longa, ascendens vel paene erecta; ala dorsalis 6.5-8 mm lata; nux 5-6 mm longa, 3-4 mm alta. Shrub 1-2 m tall, the younger stems tightly and persistently sericeous with minute dark brown hairs, the older stems with many punctiform lenticels erupting through the disintegrating epidermis. Leaves strictly decussate; lamina of larger leaves 7-8.5 cm long, 2-3 cm wide, flat, narrowly ovate, broadly cuneate to rounded at base, gradually or more abmptly tapered to a narrowly acute or acuminate apex, on the abaxial side with one or two rows of 5-10 small impressed glands somewhat within the margin and mostly on the proximal %, probably initially sericeous on both sides but the adaxial surface soon quite glabrate, the abaxial surface also soon glabrescent but with some of the very short (0.15- 0.2 mm ) sessile, tightly appressed brown hairs persistent at least for a while, especially proximally on and near the midrib; very fine reticulum equally visible on both sides in dried leaves, the finest subdivisions almost as prominent as the lateral veins; petiole 4-7 mm long, persistently sericeous with minute brown hairs, mostly with two sunken glands near middle and occasionally two more near apex; stipules not seen. Inflorescence tightly sericeous with reddish and dark brown hairs, of unbranched pseudoracemes axillary to vegetative leaves, plus one terminal; each pseudoraceme 3-8 cm long, open, with 8-14 strictly decussate flowers; bracts mostly deciduous before maturation of the fruit, only 2 seen, 1.8-2.2 mm long, ovate or elliptical; peduncle (in fruit) 1-2.5 mm long; bracteoles 1-1.3 mm long, 0.6-0.8 mm wide, elliptical, spreading or ascending, sericeous on both sides, apparently eglandular, at apex of peduncle, persistent or deciduous before maturation of fruit; pedicel 4.5 -5.5 mm long (in fruit), sericeous. Flowers with sepals revolute in fruit, ca. 2.5 mm long, ca. 1.5 mm wide, triangular, abaxially densely sericeous, adaxially moderately sericeous or appressed-tomentose, the lateral four sepals with eight elliptical glands 1.5-2 mm long, the anterior sepal eglandular or with one small gland. Petals not seen, presumably yellow. Fertile stamens 10; filaments ca. 2.5 mm long, glabrous; anthers ca. 1 mm long, glabrous, the connective mostly dark red, distally and laterally yellow. Ovary densely sericeous; styles ca. 2.5 mm long in fruit, bearing a short pointed dorsal hook at apex. Samara 17- 20 mm long, ascending to nearly erect; dorsal wing 6.5-8 mm wide, the abaxial edge curving gradually upward throughout its length, somewhat more strongly so distally than proximally; nut 5-6 mm long, 3-4 mm high. The epithet ayacuchensis refers to Puerto Ayacucho, the source of the only known collection. Heteropterys ayacuchensis, like H. maguirei, belongs to subgenus Parabanisteria, all of whose species have yellow petals, which is my reason for assuming that its petals will prove to be yellow when it is collected in flower. It is probably most closely related to H. atabapensis W . R. Anderson, another species of Amazonian Venezuela and adjacent Colombia, whose range does not extend quite as far north as Puerto Ayacucho. The two share such features as a shrubby habit, flat glabrescent leaves, open pseudoracemes, small bracts and bracteoles, adaxially hairy sepals, and small fruits.

Discussion:

Type. Venezuela. Territorio Federal Amazonas: Estacion de Piscicultura de Puerto Ayacucho, at the N edge ofthe Laja Grande, between the highway to Samariapo and the landing strip of the Puerto Ayacucho airport, 5°37'N, 67°36'W, elev. 75 m , 23 Aug 1977 Otto Huber 991 ( H O L O T Y P E MICH!; ISOT Y P E VEN!).

The epithet ayacuchensis refers to Puerto Ayacucho, the source of the only known collection. Heteropterys ayacuchensis, like H. maguirei, belongs to subgenus Parabanisteria, all of whose species have yellow petals, which is m y reason for assuming that its petals will prove to be yellow when it is collected in flower. It is probably most closely related to H. atabapensis W . R. Anderson, another species of Amazonian Venezuela and adjacent Colombia, whose range does not extend quite as far north as Puerto Ayacucho. The two share such features as a shrubby habit, flat glabrescent leaves, open pseudoracemes, small bracts and bracteoles, adaxially hairy sepals, and small fmits. The most obvious differences between them are summarized in the following couplet:

Leaves strictly decussate, the lamina narrowly acute or acuminate at apex, the reticulum with its finest subdivisions almost as prominent as the lateral veins; petioles 4-7 m m long, mostly bearing 2 sunken glands near middle; most bracts and some bracteoles deciduous before maturation of the fruits H. ayacuchensis.

Leaves opposite, alternate, or whorled, obtuse or rounded at apex, the lateral veins distinctly more prominent than the finest veinlets; petioles 0-2 m m long, eglandular; bracts and bracteoles persistent past maturation of the fmits H. atabapensis.