This species is rather widely but infrequently collected. It is characterized by the combination of its vining habit,. corollas with the tube shorter than the lobes, and exserted stamens. This identity of this species was clarified by Lorence et al. (2012). It tends to have racemiform inflorescences that are no longer than the leaves, and laterally flattened fruits.
The identity of this name has been widely confused with Chiococca pachyphylla. This confusion includes misidentification of various specimens, and a reversed application of these names by Burger & Taylor (1993) and in many herbarium identification. Chiococca pachyphylla differs in its erect, small tree habit, and generally by its inflorescences as long as or longer than the leaves with at least one pair of secondary axes, fruits that are not flattened, and corollas with longer tubes and the anthers included. However, the flowers of the plants included by Lorence et al. (2012) in Chiococca pachyphylla have two forms, the one noted above with included anthers, and another with a short corolla tube and exserted anthers. The flowers of this second form are similar to those of Chiococca phaenostemon, but these species are separated by their vining vs. erect habits, inflorescence form, and apparently flattened vs. rounded fruits. The separation of Chiococca phaenostemon and Chiococca pachyphylla is often complicated because growth habit is not noted on many labels, and many plants lack flowers. The flowers of some Chiococca pachyphylla plants are similar to the characteristic form of Chiococca phaenostemon, but there is variation in the length of the corolla tube and degree of inclusion of the anthers. Lorence et al. were not able to conclusively separate the two flower forms of Chiococca pachyphylla as two species during the scope of the work on the Flora Mesoamericana, but this certainly deserves further study.
Lorence (1999) discussed the possible typification of Chiococca phaneostemon in some detail, and concluded that its type was a the collection Schiede & Deppe 255 at HAL. However, in their detailing of the types at HAL, Braun & Wittig (2003) noted that no specimen corresponding to this name has been located there, so his designation cannot be considered an effective lectotypification.