Variation in the ant species associated with myrmecophytes (plants that provide their associated ants with nesting space, and sometimes with a complete diet) has been noted at both the regional and local levels, with plant distribution generally wider than that of the ants (Fonseca & Ganade 1996). This is the case for Cordia nodosa Lamark (Boraginaceae, subfamily Ehretioideae) whose most frequent associate ant species in Peru are Allomerus demararae (Wheeler) and Azteca spp. (Yu & Pierce 1998), while Azteca sp.1 and Allomerus octoarticulatus are the most frequent in Amazonian Brazil and French Guiana, respectively (Fowler 1993, Solano et al. 2003). Cordia nodosa plants are understorey treelets mostly less than 2 m tall, but taller individuals can be found. Their domatia are swollen, hollow stem nodes that form as the growing shoot tip invaginates through a subapical pore that then closes over when the domatium is mature (Yu 2001). So, plant-ants must reopen the chamber where the pore used to be, thus forming a kind of prostoma.

The poor availability of suitable substrate and nutrients strongly limits the distribution and growth of vascular epiphytes in lowland rain forests (Benzing 1990, Nieder et al. 2000). In some epiphyte species nutrition may be assisted by adventitious roots that grow into animal debris in plant cavities such as domatia and bromeliad tanks (Huxley 1980). For epiphyte species lacking these modifications, animals may nevertheless play a substantial role by providing a large proportion of the limited substrate in lowland forests (Catling 1995, Longino 1986). Such associations between epiphytes and nutrient/substrate-providing animals may often be non-specific and commensalistic (Davidson & Epstein 1989, Longino 1986), while highly evolved mutualistic associations occur in the case of ant gardens which are very abundant in neotropical forests (Huxley 1980, Kleinfeldt 1986, Ule 1901). Ant gardens typically are densely inhabited by different epiphytes from various plant families whose seeds or fruits are attractive to the ants and carried into the nest (Davidson 1988). In addition, ants have been suggested to play a role in protection and nutrition of ant-garden epiphytes (Kleinfeldt 1978, 1986). Ants may benefit from epiphytes through increased nest stability (Yu 1994) or nutrition via extrafloral nectaries, fruit pulps or seed arils (Davidson 1988, Kleinfeldt 1986). In this study,we compare the nutrient quality of such ant gardens with other similar substrates rarely inhabited by epiphytes, namely nests and galleries of ants and termites.