Attalea (palm) - Taxonomy

Taxonomy

Attalea has been placed in the subfamily Arecoideae, the tribe Cocoseae and the subtribe Attaleinae, together with the genera Allagoptera, Beccariophoenix, Butia, Cocos, Jubaea, Jubaeopsis, Lytocaryum, Parajubaea, Syagrus and Voanioala. Within this subtribe, Attalea has been found to be a monophyletic group, and sister to the clade containing Allagoptera, Polyandrococos, Parajubaea, Butia and Jubaea.

Disagreement exists as to whether Attalea should be considered a single genus, or a group of related genera. In their 1996 Field Guide to the Palms of the Americas, Andrew Henderson, Gloria Galeano and Rodrigo Bernal combined all the species in the subtribe Attaleinae (as it was then defined) into a single genus, Attalea. In his 1999 Taxonomic Treatment of Palm Subtribe Attaleinae, American botanist Sidney F. Glassman divided the group into five genera—a more narrowly defined Attalea, Orbignya, Maximiliana, Scheelea and Ynesa. Rafäel Govaerts and John Dransfield recognised a single genus in their 2005 World Checklist of Palms, and Jean-Christophe Pintaud continued this usage in his 2008 review of the genus.

The multi-genus approach is based solely on the structure of the male flowers; no other characters could be consistently associated with one genus or another. Four of the genera—Attalea (in a narrow sense), Orbignya, Maximiliana and Scheelea—correspond to four different types of male flowers found within the genus. However, a few species have flowers that are intermediate between these four types, including A. colenda (which Glassman placed in its own genus, Ynesa) and this has been used as an argument for the single-genus approach. In addition, there are several hybrids between species that would be considered different genera under Glassman's five-genus system, which has also been used as an argument for placing them in a single genus. In 2009 Alan Meerow and colleagues published a molecular phylogeny of the subtribe which found that some species placed in Orbignya were actually more closely related to species placed in Scheelea than they were to other members of that genus (if the five-genus approach was used), while A. crassispatha, placed in Orbignya by Glassman, was actually a sister to both Scheelea and Orbignya.