Ants of the Canary Islands

Espadaler (Espadaler and Bernal 2003, Espadaler 2007) has studied the ant fauna of the Canary Islands. A list of species is found here. The following are some pertinent notes about what he has found, and problems that remain to be resolved.

Natives and exotics Seven ant species I consider as exotics on El Hierro:, Cardiocondyla emeryi, Pheidole teneriffana, Tetramorium caldarium, Paratrechina longicornis, Nylanderia jaegerskioeldi, Tapinoma melanocephalum, and Linepithema humile. But for the last species, the other are new records for the island; not a good prospect. Fortunately, those exotics are restricted to heavily disturbed habitats, the streets and gardens, with the exception of the Argentine ant that, in addition, can occupy habitats rather well preserved, as the extensive southern pine forests in the surroundings of El Pinar. Probably only this last species is of some concern in conservation terms.

Future research It is difficult to ascertain the completeness of any inventory if, as mine, it is based on a non-systematic and non-quantitative sampling scheme. The ant species number of El Hierro, given the small island size, is probably rather complete in the native complement; exotic species such as Monomorium pharaonis or Pheidole megacephala, already known from other Canary Islands (Espadaler & Bernal 2003), the Azores (Wetterer et al., 2004) or Madeira (unpublished observations), can arrive haphazardly and establish in urbanized habitats. A few taxonomic problems remain: the specific identity of Plagiolepis, with the aptery problem at its center, deserves an all Canary Islands sampling program, in concert with a revision of the West-Mediterranean Plagiolepis. The population of Hypoponera ragusai is a taxon still to be settled, pending a revision of Hypoponera. The proper evaluation of the morphological differences of Crematogaster alluaudi merits intensive collecting as El Hierro, in spite of being the youngest island, may have already produced some genetic segregation. Pestano et al., (2003) found substantial molecular differentiation in populations of some bat species from El Hierro as compared with bats from other Canary Islands. Lastly, the finding of the male caste in Monomorium wilsoni would allow a complete specific description.

The laurisilva, a most interesting but poorly studied habitat is somehow deceptive in its species-poor myrmecofauna. I have had the same deceiving impression when visiting other Macaronesian islands. This scarcity is probably due to the dense canopy that intercepts nearly all incoming radiation (Aschan et al., 1994) thus rendering difficult ant nesting.

The endemic Monomorium from the Canary Islands offer an interesting specific diversification on which to establish morphological and molecular phylogenies, and deduce sequential colonization of the islands, as did Juan et al., (1996) with the beetle genus Hegeter.