Monographs Details: Marlierea karuaiensis (Steyerm.) McVaugh
Authority: Maguire, Bassett. 1969. The botany of the Guayana Highland-part VIII. Mem. New York Bot. Gard. 18: 1-290.

Aulomyrcia karuaiensis Steyerm., Fieldiana Bot. 28: 1005. 1957.

In 1958 this species and M . maguirei McVaugh were contrasted as follows: Plants (except the vegetative buds) completely glabrous; leaves 1.5-2.5 cm wide, elliptic, 2.3-3 times as long as wide. M. karuaiensis.

Young shoots and inflorescence thinly pubescent; leaves 0.3-1.6 cm wide, mostly lanceolate, 4-9 times as long as wide. M. maguirei.

This key served to separate two species known from two collections each, especially as the two were from widely separated localities. N o w one additional specimen from each region is at hand, and it seems that the two supposed species are more alike than originally supposed. The original collections of M . karuaiensis were from Ptari-tepui and Apacara-tepui, respectively; the following collection, from the same general region, would key out above to M . maguirei except that the herbage is quite glabrous: V E N E Z U E L A . Bolivar: Auyan-tepui, along Rio Churun, elev 1660 m, 12 M a y 1964 (fl), Steyermark 93765 (MICH).

The following collection, from a cerro on which M . maguirei might be expected, has the pubescence of that species but the leaves 3-4 times as long as wide; that is, relatively broader than in the original specimens: V E N E Z U E L A . Amazonas: Cerro de la Neblina, Cafion Grande E of Cumbre Camp, elev 1100 m, 24 Nov 1957 (fr), Maguire et al 42201 (MICH).

In summary, the differences between Marlierea karuaiensis and M . maguirei are almost nonexistent; in the latter the young herbage (not the mature leaves) is sparingly pubescent; and in the former the leaves are sometimes (but not always) elliptic and obtuse. I suspect that when more material becomes available, the two species may properly be united taxonomically.