Allograpta obliqua belongs to a group, Allograpta obliqua species group, characterized by: face straight, with low indistinct tubercle of variable size; oral opening about 1.5 as long as wide, with oral apex at level of antennal base; antennal pits confluent; plumula well developed; subscutellar fringe distinct; wing partially bare basomedially, without apical dark macula; alula broad, about 1.5 times as broad as cell BM; metasternum pilose; abdomen elongate (mengual et al. 2009).
Allograpta obliqua differs from other species in this group by: scutellum yellow or unicolorous; katepimeron yellow, forming a continuous yellow band from anepisternum to katatergum; 4th tergum medial black vittae and with a pair of parallel yellowish vittae; mesonotum not continuously yellow laterally, black behind transverse suture. The most characteristic feature is the two parallel yellow vittae and two oblique yellow vittae on 4th and 5th terga.