Tetramorium caespitum

Tetramorium caespitum (Linnaeus, 1758) (Figure 36) Formica caespitum Linnaeus, 1758, p. 581 (w.) Sweden. Palaearctic. Diagnosis Worker. TL 2.5–4 mm; uniform black-brown to black; head with parallel sides and straight posterior margin in full-face view; eyes of medium size with about 7 ommatidia on longest row, located at midline of head in full-face view; anterior clypeal margin without anterior emargination; propodeal spines short, broadly denticulate, and upward directed; head and mesosoma regularly longitudinally striate; metanotal groove distinctly impressed; dorsum of petiolar node smooth or with feebly microreticulate; gaster smooth and shining. Material examined One site: B. Geographic range. A Holarctic species geographically distributed from the USA to Japan, North Africa to all of Europe (Collingwood 1979; Wagner et al. 2017), and presumably native to the Palaearctic (Seifert 1996) or the Oriental (Smith 1965) regions. On the Arabian Peninsula it was recorded from the KSA (Aldawood and Sharaf 2009). Ecology and biology. The nesting habits of T. caespitum range from natural to urban environments (Collingwood 1979; Seifert 2007). The natural habitats include the open borders of woodlands, meadows, pastures, heaths, arid or semi-arid grasslands, vineyards, fallow grounds, ruderal areas, road embankments, rock heaps, gravel pits, and riverbanks, while the urban territories include public parks, pavements, and roadsides (Klotz et al. 2008). Nests are constructed directly in the earth, under stones, or in rotten or dead wood (Smith 1965; Collingwood 1979) and there is frequently a single queen (monogyny) with thousands of workers (Seifert 1996), or polygyny (Martinez 1993). The species is a generalised seed harvester and an active predator on arthropods, and attends aphids for honeydew (Smith 1965; Wagner et al. 2017). A nest series at the Asir Mountains (KSA) was found in leaf litter and among grasses of the family Gramineae and coexisting with a single worker of Oxyopomyrmex nitidior Santschi, 1910 (Aldawood and Sharaf 2009).