A teratological holaspid pygidium of Eugonocare (Pseudeugonocare) bispinatum (Kobayashi, 1962) is described from the Cambrian Machari Formation of Korea. The abnormality is represented by the development of two additional posterolateral spines on the left side. This feature probably resulted from a genetic defect. The nonlethal mutation caused formation on one side only of a spine array that mimics the spine arrangement of several Eugonocare species combined.

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