Monographs Details: Arachnothrix colombiana (Rusby) Steyerm.
Authority: Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.

Rondeletia colombiana Rusby, Deser. N. Sp. S. Am. PI. 129. 1920.

Type. Forest, Sierra de Onaca, Colombia, alt 1500 m, 22 Aug 1898, Herbert H. Smith 1813 in part (holotype NY).

This species differs from Arachnothrix ovata (Rondeletia ovata) in the pronounced and greater number and development of calvcine squamellae in the sinuses of the calyx-lobes, the densely strigose-scriceous hypanthium with stiffer hairs instead of loose spreading arachnoid or subvillous pubescence, the strigillose-sericeous instead of sparsely subarachnoid corolla-tube, subequal calyx-lobes with more pubescence externally, floccose-lanate instead of arachnoid young leaves, and more densely villous older mature leaves which are not subappressed crisp-strigillose on the midrib and lateral nerves beneath as in A. ovata.