Durham et al. (1980) were the first to recognize that H.L. Clark's (1948) D. mexicanus and D. rugosus were identical with Grant and Hertlein's (1938) fossil D. vizcainoensis. Diagnostic characters to separate these species were found to be unreliable (see Mooi, 1997: p. 264-265).
Mooi, R. 1997. Sand dollars of the genus Dendraster (Echinoidea: Clypeasteroida): Phylogenetic systematics, heterochrony, and distribution of extant species. Bulletin of Marine Science 61, 343-375.
Durham, J.W., Wagner, C.D. & Abbott, D.P. 1980. Echinoidea: The sea urchins. In: R.H. Morris, D.P. Abbott & E.C. Haderlie (eds), Intertidal Invertebrates of California, pp. 16-176. Stanford University Press; Stanford.