Monographs Details: Psychotria macrophylla subsp. anomothyrsa (K.Schum. & Donn.Sm.) Steyerm.
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Discussion:

Psychotria anomothyrsa Schum. & Donn. Sm., Bot. Gaz. 35: 3. 1903.

Hoffmannia striata Rusby, Descr. N. Sp. S. Amer. PL 134. 1920.

Psychotria macrophylla var angustissima Standi., Field Mus. Publ. Bot. 22: 203. 1940.

“Psychotria macrophylla” of Standl. in part, Field Mus. Publ. Bot. 13: 197. 1936, not R. & P.

Psychotria tolimensis Wernh., Kew Bull. 1914: 68. 1914.

Psychotria nicotianaefolia Mart. & Gal., Bull. Acad. Roy. Brux. 11: 229. 1844.

Psychotria laevis var angustifolia Benth., Vidensk. Meddel. 1852, no. 2. 1852.

This taxon is distinctive with its thin, few-nerved (8-16 each side) leaf blades, which are usually long acuminate or attenuate at each end, relatively elongated (2 1/2- 5 times longer than broad), dull or only pale green lower leaf surface, the latter glabrous and without any manifest tertiary venation, always white-fruited with conspicuously costate fruits, the 5 ribs of each pyrene obtusely ribbed, the slender peduncle with usually 3 or 4 tiers in the inflorescence, the flowers in small groups of 1, 2, or 3 along the axes or few grouped together at the ends, arranged with the lowest axes either once divaricate at the dichotomous ends or branched.

However distinct this taxon may appear, intermediate specimens are found between it and subsp macrophylla with perplexing series of apparent intragressions and crossing over. Some of these intergradations combine the white fruits and leaf shape of subsp anomothyrsa with the branched inflorescence of subsp macrophylla. Other intergradients manifest the leaf shape and inflorescence branching of subsp macrophylla but with the fewer-nerved leaves and white fruits of subsp anomothyrsa, or even the red fruits typically of subsp macrophylla, while other intermediates suggest other combinations and recombinations in Ecuador and Peru with the inflorescence branching and red fruits of subsp macrophylla and the fewer-nerved leaf blades of subsp anomothyrsa.

Too much variation exists in the width of the leaf blade of subsp anomothyrsa, which, although often narrowed to 2.5-4 cm wide, grades into the wider dimensions of typical subsp macrophylla. The various intermediates between subsp anomothyrsa and subsp macrophylla make it often difficult to separate the two, and hybridization between them appears to be highly probable.

Standley combined the white-fruited collections of subsp anomothyrsa in Peru (Killip & Smith 26713, 29599, 29701 and Schunke 223) with orange- and red-fruited Peruvian collections of typical subsp macrophylla in his Rubiaceae of Peru (Field Mus. Publ. Bot. 13: 197-198. 1936), but conceded that more than one species might be represented in the taxon, since it exhibited a large amount of variation, “especially in the shape of the leaves and form of the inflorescence,” but he was not able to subdivide the material satisfactorily. He was also puzzled by the color of the fruit variation in P. macrophylla subsp macrophylla, stating in his Rubiaceae of Colombia (Field Mus. Publ. Bot. 7: 103. 1931) that “In some of the specimens the fruit is described as red or orange, but if these notes are correct, it is probable that the specimens belong to a distinct species whose characters are not apparent in the material at hand.”

The following specimens indicate various degrees of overlapping and intermediate types between subsp anomothyrsa and subsp macrophylla:

With the inflorescence and red fruit of subsp macrophylla, but few-nerved leaves of subsp anomothyrsa: Peru (Killip & Smith 27637, 28483, 28578, 28589), Ecuador (Cazalet & Pennington 7668), and Colombia (Killip 5264).

With the inflorescence branching and leaf shape of subsp macrophylla, but fewer-nerved leaves of subsp anomothyrsa, and with either white fruits (of the anomothyrsa parentage) or red fruits (of the subsp macrophylla parentage): Peru (Killip & Smith 23981, 28253), Ecuador (Jativa & Epling 735), Colombia (Cuatrecasas & Willard 26152 and Fernandez 272 ).

With the inflorescence branching of subsp macrophylla, but the leaf shape of subsp anomothyrsa, and the white fruit of subsp anomothyrsa or subsp macrophylla: Colombia (Fosberg 21323; Toro 563; Andre 2035).