Pachybrachys spumarius, Suffrian, 1852

Barney, Robert J., 2019, Key to All Sixty-Four Species of Pachybrachis Chevrolat (Coleoptera: Chrysomelidae: Cryptocephalinae) in the Eastern USA, The Coleopterists Bulletin 73 (1), pp. 85-96 : 89

47. Median lobe tube-like, narrowing sharply to nodule ............ 54. P. spumarius Suffrian

47 ʹ. Median lobe not tube-like, various .......... 48

48. Yellow, standard brown/black maculae on elytra absent or reduced to four spots ................. 49

48 ʹ. Not primarily yellow, standard brown/ black maculae on elytra variable to entirely black .............................................. 51