Originally described as a species new to science in 1992 by herpetologists Richard Thomas and Blair Hedges, it is named after Nicholas Plummer who was one of the collectors of the holotype.

[3] This character is diagnostic, and distinguishes this species from S. streptophorus, S. armstrongi and S. ariasae, all of which are closely related to S. plummeri, but have considerably smaller dorsal scales.

[2] Dosal ground color is pale brownish to grayish, distinctly speckled with darker brown to black scales.

Although they share the same habitat, niche segregation is especially evident in these two species, as S. plummeri is usually associated with decaying organic matter, while S. thompsoni is saxicolous and associated with the karst itself.

Other reptiles and amphibians known to be sympatric with S. plummeri include: Leiocephalus barahonensis, Anolis brevirostris, A. olssoni, A. longitibialis, Pholidoscelis lineolatus, P. taeniurus, P. chrysolaemus, Celestus curtissi, Hypsirhynchus parvifrons, Uromacer frenatus and Eleutherodactylus alcoae.