- annular spiracle
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(ARTHROPODA: Insecta)1. In immature Lepidoptera and Hymenoptera, simple, ring-like spiracles with a single opening with no accessory chambers.2. In other immature insects, may be biforous, having two small or large accessory or secondary chambers usually adjacent to the margin; uniforous, when opening occurs on the margin, or multiforous if three or more openings are present.
Online Dictionary of Invertebrate Zoology. A.R. Maggenti and S.L. Gardne. 2005.