Plant of the Week: a new tree species (ANNONACEAE Guatteria sancti-crucis) for Peru and Bolivia

An important tree species in Madre de Dios department of Peru has finally been described as a new species:  Guatteria sanctae-crucis.  This tree in the family Annonaceae  (which includes the pawpaw of Eastern North America, and the Custard Apple, Guanabana or Soursop of the American tropics) was first collected in 1974 in the Manu Park of Southeastern Peru by Robin Foster (Ecologist, ECCo and Adjunct Curator, Botany).  It has since been collected several times in the same region of Peru, where it is frequent along the river floodplains, and as far south as Santa Cruz department (hence the name) in Bolivia.  Until last year, none of the experts in this family who reviewed our specimens could put a definitive name on it.  

Guatteria sanctae-crucis: flowering (left), unripe fruit (right).

This difficult genus, Guatteria, has more than 250 species in the American tropics and no taxonomists were willing to take the time and trouble to start revising them.  Finally the problem is being attacked by botanists in the Netherlands, led by Paul Maas, who have been revising all the Annonaceae and saved this genus for last.  This is an example of a phenomenon recently described that a large percentage of new plant species being published were collected much earlier and have been sitting in herbarium collections of museums for a long time.  This means that we probably have a great many species in Field Museum's plant collections that have never been named and described.

R Foster & N Hensold.

Links to some of our specimens of G. sanctae-crucis:  flowering  fruiting

Publication which includes this species: 

Maas, P.J.M.; Westra, L.Y.T.h. 2010. New species of Annonaceae from the Neotropics and miscellaneous notes.  Blumea 55: 259-275.