peritreme
From ZooTerms (Dictionary of Invertebrate Zoology)
peritreme (noun; Greek peri, around; trema, hold): 1. (Arthropoda: Chelicerata) In Acari, a concave plate surrounding a stigma (=spiracle).
2. (Arthropoda: Insecta) An annular sclerite surrounding a spiracle.
3. (Mollusca: Gastropoda) see peristome.
