Monographs Details: Coryphothamnus auyantepuiensis (Steyerm.) Steyerm.
Authority: Maguire, Bassett. 1965. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 12 (3): 1-285.
Discussion:Pagamea auyantepuiensis Steyermark, Fieldiana Bot. 28: 584. fig. 129. 1953.
At the time of the original description the fruit was unknown. The followin is description of the fruit and seeds is drawn from the specimens of Vareschi & Foldats 4930 and Pannier d Schwabe, together with an emended description of the flowers, based upon the examination of additional material now available.
Pedunculus 16-23 cm longus; calycis lobis 3-5, 2.8-4 m m longis; corolla 5.7-8 mm longa, tubo 2-4.5 mm longo, lobis 3-3.5 mm longis 1.2-1.5 mm latis; ovario 1 mm alto 2 m m lato plerumque 4-lobato glabro apice truncato; stylo 2.5-5 mm longo glabro praeter 20 glandulas cylindricas sessiles basi exceptas; fructu osseo nitido ovoideo negro 3.5-4 mm longo ad hypanthium parte basilari 1.5 mm adnato supra lobos calycis libero apice pilis papillatis persistentibus instrueto; seminibus 2 vel 4 negris carnosis primum verticaliter faciebus interioribus conjunctis deinde disjunctis rugulosis immaturis 2.5 m m longis 1.5 m m latis.
The ovary is only slightly inferior or nearly free. Although 2-celled, the dissepiment is thin and weakly developed, easily breaking and presenting an apparently but falsely 1-celled ovary. The 6-8 ovules are borne on axile placentae.
Dr. Richard S. Cowan, after studying the specimen of Tate 1365 (holotype of Coryphothamnus auyantepuiensis), concluded that the ovary was 2-celled with 3 axile ovules in each cell. The capsule at first is 2-celled, but soon splits into 4 sections. It is adherent to the basal 1.5 m m of the lower part of the hypanthium, but free above the calyx-lobes. The 2 or 4 seeds, apparently arising at the base of the cell, are attached together vertically by their inner faces. The capsule dehisces septicidally, opening from the summit downward into two main valves, which eventually split into four sections or divisions.
It is interesting to note here that Dr. Cowan independently reached the conclusion that the Tate 1365 specimen belonged to an undescribed genus related to Pagamea. It seems noteworthy to quote from his notes of July, 1956 attached to the holotype specimen: '' This plant was originally thought to be a Pagamea, but the placentation makes this somewhat dubious. The ovary is superior here as ia that genus but in the other species described in the last few years the ovary varies from completely superior to completely inferior in the various species. The latter are however all 2-celled with uniovulate cells (as for Pagamea). The 3 axile ovules in each cell of the Tate collection [2-celled ovary] does not fit Pagamea at all and if it is included in Pagamea by emending the generic characters, then might not the genus be also emended to include those species described in Pagamea which have inferior ovaries or 1/2-inferior ovaries? If so, then how will species of inferior ovaries be separated from other genera with inferior ovaries ? Furthermore, P. steyermarkii has a uniovulate 1-celled ovary which must be considered as inferior, although admittedly the union between the calyx and ovary may be broken. I have concluded that Tate 1365 probably is not Pagamea, but that it m a y represent a new genus allied to Pagamea. I have searched through the Rubiaceae, Loganiaceae, etc. and still feel that is rubiaceous in its affinities but even this is uncertain.''
Now that specimens are known with fruit, it is obvious that the taxon from Auyan-tepui is generically distinct, not only from Pagamea Aubl. proper, but as well from Aphanocarpus steyermarkii (formerly placed in Pagamea).