Macroderes undulatus can be separated from other Macroderes species by the combination of the following characters: head with small tubercle in the middle of frontal suture; base of pronotum with large, adjoining punctures becoming sparser and smaller towards anterior margin; metasternum smooth, without distinct punctuation; elytral intervals with sparse punctures surrounded by matte areas separated by smooth elevated areas.
The range of Macroderes undulatus in unclear since most of the older specimens have locality label “Cape of Good Hope”. The only exact locality record available, “Rietpoel”, although probably originally misspelled, suggest western Cape distribution.