Tetramorium caespitum (L.)

Bolton, B., 1979, The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Malagasy region and in the New World., Bulletin of the British Museum (Natural History) Entomology 38, pp. 129-181 : 171

Tetramorium caespitum (L.)

(Figs 37, 49)

Formica caespitum L., 1758: 581 . Holotype female, Europe (' in Europae tuberibus') (holotype not in Linnean Society collection, London). Tetramorium caespitum (L.) ; Mayr, 1855: 426. Tetramorium caespitum var. immigrans Santschi, 1927: 54 . Syntype workers, Chile: Valparaiso (Miss Edwards) (probably in NM, Basle; not seen). Syn. n. Myrmica (Myrmica) brevinodis var. transversinodis Enzmann, 1946: 47 , figs 1, 2. Holotype worker, _ U. S. A.: Massachusetts, Dedham (in private coll. J. Enzmann ; not seen). [Synonymy by Brown, 1949: 47; also Creighton, 1950: 291.]

Worker. With the group characters given above; the head densely and finely longitudinally rugulose everywhere. Spaces between rugulae with feeble ground sculpture, mostly shining. Head without unsculptured patches, without reticular or rugoreticular sculpture. Dorsal alitrunk longitudinally rugulose but on the posterior portion of the propodeal dorsum the rugulae being replaced by fine reticulatepunctate sculpture. Dorsal surfaces of petiole and postpetiole finely sculptured but each with a smooth median area or smooth median longitudinal strip. First gastral tergite unsculptured. Metanotal groove impressed in profile, the propodeal spines usually slightly longer than their basal width, but sometimes represented only by a pair of broadly triangular teeth. Pubescence of hind tibiae short and fine, decumbent to appressed.

During this study I have examined specimens from Massachusetts, New York and Pennsylvania, all falling within the range given by Creighton (1950). The var. transversinodis of Enzmann , noted above, is accepted as an absolute synonym of caespitum without question for, although I have not seen the holotype, the figures and description fit the species very well.

The status of var. immigrans is a little more dubious. It was first recorded from Chile by Santschi (1922) as T. caespitum but later he described it as caespitum var. immigrans (1927), both records being based on the same specimens from Valparaiso. Snelling & Hunt (1975) in their review of the Chilean ant fauna note the 1922 record but state that they had seen no material in their survey. Under these circumstances I think it best to assume that the Chilean record represents a casual introduction and to refer immigrans to the synonymy of caespitum . Sporadic introductions of caespitum in the neotropics are probably uncommon but I have seen material originating in Belize and Mexico during the course of this investigation.