Formica rufibarbis
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| Formica rufibarbis Fabricius, 1793 |
Formica rufibarbis is a European formicine ant of the Formica fusca group. In the classification by Auguste Forel, it is treated in the subgenus Serviformica (see Forelian subgenera of Formica).
It is locally common throughout continental Europe, and ranges from Portugal to Western Siberia.
It is most distinguishable by the large amounts of red coloration on the head and alitrunk, and its profuse outstanding hairs on the pronotum and the upper margin of the petiole scale.
The name Formica rufibarbis was first given to this ant by Lord Avebury in Britain in his important work Ants, Bees and Wasps in 1881, although the species had been noted (misidentified as F. cunicularia) by Frederick Smith in 1851.
In Britain, the species has always been scarce, confined to Surrey heathland.
In the 1927 edition of British Ants: their life histories and classification, Donisthorpe gives its distribution as being confined to Reigate, Ripley, Chobham and Weybridge. It has not been recorded in the former and latter of these localities in recent times, and the remaining populations in the other two are most precarious, with colony numbers thought to be in low double figures.
F. rufibarbis nests completely within the ground, usually in sandy banks, and nest chambers situated about a foot beneath the surface are accessible only from a single entrance. This makes the locating of colonies very difficult, so it is possible that the tiny numbers of recorded colonies constitute an under-representation.
Workers forage singly, and demonstrate remarkable mettle in comparison to the cowardly habits of Formica fusca; Donisthorpe observed:
"The workers are very audacious and will even endeavour to rob F. rufa of its prey - holding on and pulling - and the moment the rufa lets go, to get a better grip, or to attack the rufibarbis, the latter swiftly decamps with the prize."
Workers also possess a remarkable sense of sight, and will proceed to their nest entrance in a dead straight line even if major obstacles are placed to disrupt their path. Donisthorpe describes this phenomenon thus:
"On July 12th, 1913, having observed several rufibarbis workers running about on a path near a sandy bank at Weybridge, I endeavoured to find their nest, and commenced to pull up handfuls of herbage on the top of the bank, which I let fall on the slope. I then saw a worker approaching with a fly in its jaws and start to mount the bank, and as the scattered herbage was directly in its way, I feared the ant might be diverted from its nest, but when it reached the obstacle it never hesitated for a moment, but running straight over it in a direct line, entered its nest on the top of the bank, which I was thus enabled to find."
Colonies usually contain one to three queens, although the occurrence of gynaecoid workers has also been recorded. Queens found colonies single in the same manner as other ants from the Formica fusca group. Eggs are first laid early in the new year, and colonies reach a maximum size of around 500 workers.
Alates emerge in late June to early July.
Like other Servifusca, this species is subject to raids by dulotic species such as Formica sanguinea and Polyergus rufescens where their ranges coalesce. In Britain this only takes place at Chobham in the case of the former (the latter does not occur in the country).
F. rufibarbis is on the red list in Britain, although it is not considered at risk in continental Europe.
Also see British ants, Rare ants of the British Isles, List of locales in Britain where ant species have become locally extinct and List of the common names of British ant species.
See list of ant genera (alphabetical) for an alphabetical compendium of worldwide ant genera.