Paratrechina Motschulsky

Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., Fauna Entomologica Scandinavica 8, pp. 1-174 : 108-110

Genus Paratrechina Motschulsky , 1863

Paratrechina Motschulsky , 1863: 13.

Type-species: Formica longicornis Latreille , 1802.

Mandibles narrow; palp formula 6, 4. Antennae 12 segmented in female castes, 13 segmented in males. Eyes set at or in front of mid length of head. Ocelli absent in workers. Propodeum and scale unarmed. Petiole scale reduced inclined forward, in many species overhung by first gaster segment. Dorsal surface of head, alitrunk and gaster with paired coarse setae.

A pantropical genus with many species including a few in temperate Asia and several cosmopolitan species of which two are frequently introduced on plant material into Europe and become established in heated premises.

Keys to species of Paratrechina

Workers

1 Alitrunk conspicuously elongated. Antennae very long, extending backward as far as propodeum. Appendage setae long and sparse, usually absent on scapes. Length: 2.5-3.5 mm. Colour brownish black (Fig. 156)............ longicornis (Latreille)

- Alitrunk not conspicuously elongate. Antennal scape extending only as far back as mesonotum. Setae short and crowded on all appendages including scapes. Length: 2.0-3.0 mm. Colour yellowish brown to black (Fig. 157)............. vividula (Nylander)

Queens

1 Antennal scape over-reaching occipital border by over half its length, without outstanding hairs. Length: 5.0-5.5 mm................................... longicornis (Latreille)

- Antennal scape not exceeding occipital border, with numerous erect hairs. Length: 3.5-5.0 mm................................................................. vividula (Nylander)

Males

I Head longer than broad; scape without hairs. Length: 2.5 mm longicornis (Latreille) - Head not longer than broad; scape with outstanding hairs. Length: 2.0 mm vividula (Nylander)

Paratrechina longicornis (Latr.) (Fig. 156) is of frequent occurrence in the British Isles. Established colonies may be very populous with many queens and are difficult to eradicate.

Paratrechina vividula (Nyl.) (Fig. 157) has been recorded from heated glasshouses in botanic gardens in Denmark, Uppsala and Goteborg in Sweden and Helsinki in Finland as well as many places in the British Isles.