Anochetus ghilianii

This is a well-known species of southern Spain and Morocco.

Distribution
Anochetus ghilianii is the only species of the genus Anochetus found in Europe.

Distribution based on Regional Taxon Lists
Palaearctic Region: Gibraltar, Iberian Peninsula, Morocco, Spain.

Biology
Jowers et al. (2015) - The distribution of A. ghilianii is rather odd. It is the only Anochetus species occurring in Europe and is found on both sides of the Strait of Gibraltar. Its distribution and habitat preferences are quite different in Europe and Africa. In the Iberian Peninsula it is restricted to the stretches of land in close proximity to the coast of Cadiz and Gibraltar, and within these localities the populations seem restricted by river systems (Barbate and Guadiaro Rivers at the west and east, respectively). Their habitat conditions here are mainly associated with low altitude (up to 390 m) (Tinaut et al., 2011a; Tinaut, Ruano, & Martinez, 2011c) humid conditions in open or shrub habitats and leaf litter, avoiding true woodland. In contrast, in Morocco A. ghilianii shows a widespread distribution along the Atlantic coast from Tangier to Ben Slimane and along the Mediterranean coast up to Laou River (collected by AT), tolerating high altitudes (up to 1000 m and oak forest habitat) (Cagniant, 2006).

The occurrence of wingless queens in A. ghilianii and field observations (Taheri, pers. observ.) suggest that this species is likely to disperse by foot (i.e. fission). This in turn should lead to an increase in population structure and promoting an isolation by distance pattern at a local scale. Its distribution on both sides of the 14 km strait suggests they are either a). an ancient lineage, dating to prior to at least the last connection period between both Spain and Africa around 5 million years ago b). have been passivel dispersed more recently, presumably via marine dispersal (rafting on floating vegetation and logs) and/or through accidental human introductions.

Evidence from a rapidly evolving mitochondrial gene (COI) sampled from several individuals throughout the species’ Moroccan and Iberian distribution range shows there is decreasing haplotypic diversity from southern to northern localities. The same haplotype is present for all the Iberian localities and from Cap Spartel and Tangier in North Morocco, suggesting multiple reoccurring translocations through maritime traffic between ports on either side of the Strait of Gibraltar.

Clues on this species’ dispersal mode derive from morphological examination of the only four reported queens to date (Tinaut, Bensusan, & Guillem, 2011b) suggesting, as in other queens within the genus (Brown, 1978; Tinaut & Ruano, 1992), complete absence of wings indicating their inability to fly and therefore their incapability to colonize or re-colonize from either side of the Strait (Tinaut, Bensusan, & Guillem, 2011b). The four A. ghilianii queens described from Spain were accompanied by 20-30 workers, thus indicative of very small nests (Tinaut et al., 2011b). Because Anochetus nests are found a few centimetres from the surface, or as reported with A. ghillianii, present under rocks and leaf litter, it is possible to assume that whole nests have been transported across the sea in building material such as sand, soil, boulders and woods or most likely in planted flowerpots. Furthermore, a dependent colony-founding queen (through fission) needs part of the colony to survive and thus single or multiple queen colonization events are extremely unlikely.

Nomenclature

 *  ghilianii. Odontomachus ghilianii Spinola, 1851b: 55 (w.) SPAIN. [Also described as new by Spinola, 1853: 71.] Emery, 1909c: 376 (q.m.); Tinaut, et al. 2011: 161 (q.). Combination in Anochetus: Mayr, 1861: 54. Senior synonym of cameroni: Brown, 1964d: 214. See also: Brown, 1978c: 598.
 * cameroni. Anochetus cameroni Forel, 1915c: 352 (w.) BRAZIL. Junior synonym of ghilianii: Brown, 1964d: 214.

Taxonomic Notes
Brown (1964) notes that while the type locality for A. cameroni was given by Forel (1915) as "Cap Saint-Roque", Brazil, this is apparently in error; the true type locality is probably San Roque, Spain, near Gibraltar. Brown treated A. cameroni as a junior synonym of A. ghilianii. Forel had suggested a close relationship between these two species, stating that they differed in the shape of the petiolar scale and width of the head. However these differences are apparently of little taxonomic significance and the two taxa are considered to belong to a single species.