A bract (PO:0009055) that subtends an antheridium (PO:0025125). [source: ISBN:9780473067304]
Comment
When an antheridium occurs on a specialized lateral branch of the gametophore, all of the phyllomes on that branch are usually perigonial bracts. If an antheridium occurs on a main axis of the gametophore, usually only the terminal phyllomes are perigonial bracts.