Tetramorium caespitum (Linnaeus 1758)

Schifani, Enrico, Csősz, SÁndor, Viviano, Roberto & Alicata, Antonio, 2021, Ant diversity on the largest Mediterranean islands: on the presence or absence of 28 species in Sicily (Hymenoptera, Formicidae), Natural History Sciences 8 (1), pp. 55-70 : 67

18. Tetramorium caespitum (Linnaeus 1758)

Long recognized as the sole species of the caespitum complex other than T. impurum (Foerster 1850) , T. caespitum has then been recognized to be just one of 10 West-Palearctic cryptic species (Schlick-Steiner et al., 2006; Wagner et al., 2017). Consequently, previous records of T. caespitum in Sicily and elsewhere must be regarded as unreliable and, of course, including the Sicilian (see De Stefani, 1881; Baroni Urbani, 1964a; Sanetra et al., 1999; La Pergola et al., 2008). Indeed, the ecological conditions of the sites of these records may even suggest that some represent misidentifications for Tetramorium species not belonging to the caespitum complex (Sanetra et al., 1999). However, in a recent paper two of the present work authors (Schifani & Alicata, 2018) published some erroneous records of T. caespitum from Sicily: by using the on-line key provided by Wagner et al. (2017), they erroneously transcribed latitudinal and altitudinal data, which resulted in a misleading identification output. We currently recognize only the following eight Tetramorium species in Sicily: T. alpestre Steiner et al. 2010 , T. atratulum (Schenck 1852) , T. bicarinatum (Nylander 1846) , T. diomedeum Emery 1908 , T. immigrans Santschi 1927 , T. lanuginosum Mayr 1870 , T. punctatum Santschi 1927 , and T. semilaeve André 1883 (also see Sanetra et al., 1999; Schär et al., 2020). Of these, three are exotic ( T. bicarinatum , T. immigrans , T. lanuginosum ). In addition, there are three social parasites currently attributed to the genus Strongylognathus (but see Ward et al. 2015): S. alpinus Wheeler, W.M. 1909 , S. destefanii Emery 1915 , and S. testaceus (Schenck 1852) (Sanetra et al., 1999; Schifani & Alicata, 2018; Schär et al., 2020). In Sicily the hosts of social parasite species appear to be T. alpestre for S. alpinus and S. testaceus , T. immigrans for T. atratulum (but see Schifani et al., 2021b), and T. semilaeve for T. destefanii (Sanetra et al., 1999; Schifani & Alicata, 2018; Schär et al., 2020). Regarding the caespitum complex, it is worth adding that T. alpestre seems widespread across mid-to-high altitude sites of Sicily’s main mountain complexes, while T. immigrans occurs in urban or highly disturbed habitats (Sanetra et al. 1999; Schifani & Alicata, 2018; Castracani et al., 2020). However, in Sicily T. alpestre is represented by the U3 lineage sensu Wagner et al. (2017) which deserves further taxonomic investigation, so that the situation is not settled yet.