Opuntia galapageia is a species of cactus. It is endemic to the Galápagos Islands, part of Ecuador. Forms occurring on different islands have been treated as separate species and subtaxa of these species. Opuntia echios, Opuntia helleri, Opuntia insularis, Opuntia megasperma, Opuntia myriacantha and Opuntia saxicola are now sunk within O. galapageia.
Description The variety Opuntia galapageia var. myriacantha, synonym Opuntia galapageia var. echios, has one of the longest spine lengths: up to in length, exceeded only by Ferocactus emoryi ssp. rectispinus at .
Taxonomy Opuntia galapageia was first described by John Stevens Henslow in 1837. It was first recorded by Charles Darwin on Santiago (James) Island. Darwin was ashore there for nine days in 1835. Subsequently, at least five other species of Opuntia were described from the Galápagos: Opuntia helleri, Opuntia insularis, Opuntia megasperma, Opuntia myriacantha and Opuntia saxicola. All were treated by David Hunt in 2006 as included within O. galapageia, a placement accepted by the IUCN Red List as of 2017, although they had been assessed as separate species in 2000. Plants of the World Online also accepts the placement within O. galapageia, and includes Opuntia echios, in most cases placing the species in an infraspecific taxon (see the list below).
Infraspecific taxa A large number of varieties and other infraspecific taxa have been named. , Plants of the World Online accepts the following: Image Name Distribution Opuntia galapageia subvar. barringtonensis (E.Y.Dawson) Backeb., syn. Opuntia echios var. barringtonensis E.Y.Dawson Santa Fe This is the stoutest variety, with a trunk up to DBH. Opuntia galapageia var. gigantea (J.T.Howell) Backeb., syns. Opuntia echios var. gigantea (J.T.Howell) D.M.Porter, Opuntia echios subsp. gigantea J.T.Howell Santa Cruz Tallest form; up to . Opuntia galapageia var. helleri (K.Schum. ex B.L.Rob.) Backeb., syn. Opuntia helleri K.Schum. Darwin, Genovesa, Marchena, Wolf Opuntia galapageia subvar. inermis (E.Y.Dawson) Backeb., syn. Opuntia echios var. inermis E.Y.Dawson Isabela Opuntia galapageia var. insularis (A.Stewart) Backeb., syn. Opuntia insularis A.Stewart Fernandina, Isabela Opuntia galapageia var. macrocarpa E.Y.Dawson Pinzon Opuntia galapageia var. myriacantha (F.A.C.Weber) Backeb., syns. Opuntia echios, Opuntia myriacantha F.A.C.Weber Opuntia galapageia var. profusa E.F.Anderson & Walk. Isabela, Santiago Opuntia galapageia var. saxicola (J.T.Howell) Backeb., syn. Opuntia saxicola J.T.Howell Isabela Opuntia galapageia var. zacana (J.T.Howell) Backeb., syns. Opuntia zacana J.T.Howell, Opuntia echios var. zacana (J.T.Howell) Backeb. North Seymour Two other infraspecific taxa that have been named are not recognized by Plants of the World Online as distinct from the species: Opuntia galapageia var. brossettii Backeb. Opuntia galapageia subvar. orientalis (J.T.Howell) Backeb.
Distribution
Opuntia galapageia is endemic to the Galápagos Islands. Forms occurring on different islands have been described as subtaxa of the species (see the list above). Island distributions given by Plants of the World Online include:
Fernandina O. galapageia var. insularis Isabela O. galapageia subvar. inermis O. galapageia var. insularis O. galapageia var. profusa O. galapageia var. saxicola Seymour O. galapageia var. zacana Pinzon O. galapageia var. macrocarpa Santa Cruz O. galapageia var. gigantea Santa Fe O. galapageia subvar. barringtonensis Santiago O. galapageia var. profusa
References