Piper guahamense, the Guam pepper[1] (Chamorro: pupulun aniti), is a plant in the family Piperaceae, and is endemic to the Mariana Islands.

[1] Piper guahamense was first classified as being in the Macropiper genus by in 1839 by Dutch botanist Friedrich Miquel.

[3] The name Piper guahamense was first recorded in 1869 in the 16th volume of Prodromus Systematis Naturalis Regni Vegetabilis by Swiss botanist, Alphonse Pyramus de Candolle.

All were collected during a 1911 and 1936 entomological surveys of the island: The following insects are endemic to the Marianas or Micronesia and have been observed on Piper guahamense and other plant species: a spittlebug (Lallemandana phalerata),[8] a rove beetle (Palaminus swezeyi),[9] an ant-like leaf beetle (Euglenes bifossicollis),[10] a tumbling flower beetle (Mordellistena castanea), a chalcid wasp (Ooencyrtus swezeyi),[11] three planthoppers (Tambinia guamensis, Ugyops samoaensis, and Capelopterum punctatellum),[12] and four true weevils (Trigonops inusitata, Trigonops vulgaris, Daealus tuberosus, and Cryphalus swezeyi) (Elwood C. Zimmerman noted extensive perforations in the leaves of Piper guahamense due to Trigonops).

[13][14] Non-endemic invertebrates collected from Piper guahamense include a plant bug (Creontiades pallidifer),[15] a chalcicoid wasp (Spalangia endius), and a fungus weevil (Araecerus vieillardi).