This tiny ant lives inside the nests of wood ants of the genus Formica, hence the name 'guest' ant (2). Workers, queens and males are generally similar in appearance, with a smooth, shiny, reddish-yellow body. Queens are slightly darker in colour, and unusually amongst ants, the males do not posses wings (2).
Very few details of the ecology and biology of this species have been elucidated, and what it feeds on is still a mystery (3). Colonies of this species are small, numbering around a hundred workers (2), and are situated in pieces of wood or in fronds of bracken within the nest of the host (3). More than one colony can occur in a single host nest (3). The workers are not often seen, but occasionally they emerge and run around on the surface of the host nest (3). Males, which are present from July to September (3), are wingless, and mating occurs on the surface of the nest rather than during a mating flight, as in many species of ant (2). Mated queens may fly to other host nests, or may return to their own nest in order to establish a new colony (2). Host workers tend to completely ignore their 'guests', with shining guest ants moving freely inside the colony (2). However, host workers may occasionally grab F. nitidulus workers, releasing them undamaged, and very rarely they may actually attack them (2). If the hosts move to another nest, the guest ant colony follows closely behind, with queens, larvae and pupae being carried by the workers (2).
In Great Britain, this ant has been recorded where wood ant nests occur, with the exception of north and west Wales (3). The distribution extends from Devon in the south to the Scottish Highlands in the north. The shining guest ant has probably been under-recorded in many places as it is easily overlooked (3). Elsewhere, this ant has a wide distribution, extending across the Palaearctic region, where wood ants are established, but it is less common in warm Mediterranean areas (3).
This ant does not seem to favour any particular species of wood ant as a host, but it has been recorded living in the nests of the southern wood ant (Formica rufa), the hairy wood ant (Formica lugubris), and the Scottish wood ant (Formica aquilonia) in Britain (3). These species generally occur in open woodlands and scrubby areas (4).
It is not known if this species is actually undergoing a decline, but as its fate is so closely associated with that of its hosts, it suffers as a result of threats facing the host species (3). These threats include the loss of suitable habitat caused by agricultural activity and development, as well as unsuitable management of woodlands (3).
The shining guest ant is a UK Biodiversity Action Plan (UK BAP) priority species, and a Species Action Plan has been produced to guide its conservation (3). This plan aims to maintain the present range of the species. A number of sites where this ant occurs are Sites of Special Scientific Interest (SSSIs), National Nature Reserves (NNRs) or are managed sympathetically by Wildlife Trusts, the Forestry Commission, the RSPB or by private owners (3). The conservation of this species is closely tied with that of its hosts; the southern wood ant (Formica rufa) and The Scottish wood ant (Formica aquilonia) are also UK Biodiversity Action Plan species and are classified by the IUCN (the World Conservation Union) Red List as globally Near Threatened (4), (5).
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