Tetramorium

Genus Tetramorium Mayr, 1855

Tetramorium Mayr, 1855:423.

Type-species: Formica caespitum Linne, 1758.

Worker and queen. Lateral margins of clypeus raised into a ridge in front of antennal insertions; mandibles with 3 strong apical teeth followed by a row of smaller denticles. Sting with lamelliform appendage. Pronotum of worker distinctly angled anterolaterally. Body hairs simple.

Male. Antennae 10 segmented with elongate second funiculus segment, mandibles dentate. Body hairs simple.

This is a very large genus with several hundred species mainly distributed throughout the palaeotropic and palaearctic regions. One species is native in North Europe and one or more subtropical cosmopolitan species are occasionally introduced and may become established in heated premises.

Keys to species of Tetramorium

Workers and queens

1 Frontal carinae short; body colour brownish black............ 28. caespitum (Linne)

Frontal carinae extended backwards as longitudinal ridges almost to occipital margin; body colour yellowish to reddish brown.............................................. 2

2(1) Dorsum of alitrunk and petiole nodes coarsely rugulose; body hairs long and numerous. Queen has first gaster tergite with fine longitudinal striae at base (Fig. 113)...................................................................... bicarinatum (Nylander)

Alitrunk finely rugulose with numerous punctures; body hairs short and sparse. Queen has postpetiole and first gaster tergite finely punctulate simillimum (Smith)

Males

Tetramorium bicarinatum (Nylander, 1846) [stat. rev. Bolton, 1977]

Fig. 113.

Myrmica bicarinata Nylander, 1846b: 1061.

Worker and queen. Pale reddish, coarse reticulo-rugulose sculpture; frontal carinae

1 Postpetiole smooth and shining............................................ simillimum (Smith)

Postpetiole punctured or regulose.................................................................. 2

2(1) Head and alitrunk yellowish brown. Frontal carinae extend backward to level of ocelli........................................................................ bicarinatum (Nylander)

Head and alitrunk blackish brown. Frontal carinae short 28. caespitum (Linne)