peristomial
/ˌpɛrɪˈstəʊmɪəl/adjective
1 Botany. Of or relating to the peristome of a moss.
2 Zoology. Of or relating to the peristome of an invertebrate; surrounding the mouth, circumoral.
Origin
Mid 19th century. From peristomium + -al. Compare earlier peristomal.