Monographs Details: Psychotria imthurniana f. ptariensis (Standl. & Steyerm.) Steyerm.
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Description:Distribution and Ecology - Distribution. Known only from the type collection.

Discussion:

Psychotria ptariensis Standl. & Steyerm., Fieldiana Bot. 28: 604. 1953.

Type. Ptari-tepui, south-facing densely forested slopes between Río Karuai and ridge below “Misia Kathy Camp,” Estado Bolívar, Venezuela, alt 1250-1520 m, 27 Oct 1944, Steyermark 59440.

In the original description of Psychotria imthurniana the leaves are described by Oliver as “1 3/4-2 1/4 poll, longa, 1/2-2/3 poll, lata” or approximately 4.5-5.7 × 1.3-1.7 cm, or about 3 1/2-5 1/2 times longer than broad. The form ptariensis represents the elongate, narrow-leaved extreme in which the leaves are linear-lanceolate to narrowly lanceolate and 6-9 × 0.7-1.5 cm or about 8-9 times longer than broad. In f ptariensis the sides of the leaves are nearly parallel, the width being nearly the same throughout. In other specimens, such as those of Tate 1291 (type of P. auyantepuiensis) and Steyermark 93288 from Auyan-tepui, the leaves are much broader, up to 2.5-3 cm wide and only 2-3 times longer than broad, the leaf margins curved to base and apex and much wider at or below the middle. However, there are intermediates between these extremes, and it is not possible to draw any arbitrary division between one variation and another. Even in the type collection of P. imthurniana the leaves vary in shape from narrowly to broadly lanceolate to oblong-lanceolate and in width from 1.3-1.7 cm, and about 3 1/2-5 1/2 times longer than broad. The collection of Tillett, Tillett & Boyan 43971 has leaves varying in width from 0.4-2.2 cm, even on the same branch. The other collections of Tillett, Tillett & Boyan (numbers 44863 and 44814) are transitional toward f ptariensis.

Psychotria auyantepuiensis is obviously conspecific with P. imthurniana, and shows the same strong nervation beneath with the intermediate nerves and midrib prominent on the upper side, similarly thickened marginal nerve, short glabrous petiole, rounded to subcordate leaf base, slender peduncle with pedicellate slender pedicels, glabrous hypanthium, and four acute triangular calyx lobes.