H. sacchari falls into group 4 of Heterodera species, as defined by Mulvey (1972), in which the cysts are lemon- shaped, the vulval slit is >30 µ and there is generally a strong underbridge with few or many bullae. In this group, H. sacchari is characterized by having few bullae and a massive underbridge with finger-like projections, the under- bridge being 22-28 µ below the fenestral level (see keys in Mulvey, 1972).