Acacia rivalis differs mainly in always having flat phyllodes with a small gland further from the base and flower-heads 4-10 in racemes. J. M. Black, Fl. S. Austral. Pt. 2. 415 (1948), distinguished Acacia euthycarpa from A. calamifolia by its straight edged legumes which are flexuose in appearance. These do not appear to be reliable characters and at this stage Acacia euthycarpa cannot be satisfactorily distinguished from A. calamifolia. It is therefore included within it.

A. microcarpa var. linearis Black was described from material from near Monarto South and was considered to be conspecific with A. x grayana. Leach & Whiffin (1978) suggest that both of these are hybrids or intermediates between A. calamifolia and A. brachybotrya.