By Arthur O. Tucker, Michael J. Maciarello, Andrew Salywon and Leslie R. Landrum

Abstract: Abstract: Essential oils of fragrant Mosiera ehrenbergii (O. Berg) Landrum (Myrtaceae), collected in Arizona from Mexican seed, and M. longipes (O. Berg) Small, collected in Florida, were examined by GC/MS/FID. Thirty-eight constituents were identified with dominant components of limonene (51.6±0.7%) and α-pinene (33.6±2.4%) in M. ehrenbergii and limonene (47.8±2.5%) in M. longipes. Key Word Index: Mosiera ehrenbergii, Mosiera longipes, Myrtaceae, essential oil composition, limonene, α-pinene.

Introduction
Mosiera (Myrtaceae: Myrtinae) is a New World genus of 18 species of trees and shrubs, distributed mainly in the Caribbean, but with two species in Mexico, one of these also occurring in Guatemala. Until recently, many species of the genus have often been placed in superficially similar genera such as Eugenia, Myrtus and Psidium (1–4). Recent molecular phylogenetic analysis indicates that Mosiera has a sister group relationship with Psidium and is more distantly related to Eugenia and Myrtus (5).

Mosiera ehrenbergii (O. Berg) Landrum is a species of shrub or tree 0.5–4 m high that is endemic to the Mexican states of Hidalgo, San Luis Potosi and Tamaulipas in oak woodlands, chaparral, piñon woodlands, matorral and subtropical desert scrub from 900–2000 m in elevation.

Mosiera longipes (O. Berg) Small is a species of sprawling to erect shrub or tree from 0.2–4 m high widely distributed in the Caribbean from southern Florida to the Bahamas, Turks and Caicos, Jamaica, Dominican Republic, Puerto Rico, and the northern Lesser Antilles, growing in pine hammocks or in dry costal scrub from sea level to 50 m in elevation. Reportedly a tea is brewed from the leaves in Acklin’s Island, Bahamas (4). Other papers describe the essential oils of the economically important and sister genus Psidium (6–7); however, no reports exist for the chemistry of the oils of Mosiera.