M. spectabilis Péringuey, 1901, nomen dubium
The species was described from a single female from "Cape Colony" but no additional specimens were found since then and all the following authors cited the Péringuey's description. The type is absent from the South African Museum and apparently lost. The characters of the species mentioned in the original description suggest that it might be an aberrant specimen of M. bias. The description, although brief, corresponds well to the examined specimens of M. bias except for two characters indicated as diagnostic for M. spectabilis, namely "retuse prothorax which is almost lobate in front" and absence of elytral stria 9. The former character suggests that the specimen could be missexed since the retuse pronotum, excavated antero-laterally is characteristic for large males of a few Macroderes species, especially M. bias, but not found in females. Elytral stria 9 is very close to stria 10 in M. bias and it might be still closer to, or inseparable from in the exemplar Péringuey's description was based on.
Péringuey, L. 1901. Descriptive Catalogue of the Coleoptera of South Africa. - Transactions of South African philosophical Society, 12, 1-920.
Frolov, A. V. & Scholtz, C. H. 2005. Revision of the southern African genus Macroderes Westwood (Coleoptera: Scarabaeidae: Scarabaeinae). Annales de la Société Entomologique de France (N. S.), 40(3-4): 371-391.