Genus Tetramorium ^HNS Mayr, 1855

Tetramorium ^HNS Mayr, 1855:423.

Type-species: Formica caespitum Linne ^HNS, 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 ^HNS

Workers and queens

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

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) ^HNS

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

Males

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

Fig. 113.

Myrmica bicarinata Nylander ^HNS, 1846b: 1061.

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

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

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

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

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