Axinidris species: the Wood ants


TRIBE: Tapinomini

The Genus Axinidris Weber:
the Wood ants

A small genus of about 15 known species; Antwiki ( says: “Species of Axinidris appear to nest exclusively within hollow plant stems, both living and dead, and in rotten wood. They are found in forested areas throughout the Afrotropical region, but are most abundant and diverse in the moist equatorial forests. Workers are primarily arboreal foragers, but may occasionally forage in ground litter.” 
For nearly 50 years this was thought to be a monospecific genus restricted to Kenya, but Shattuck’s revision in 1991 listed 13 species, occurring in forested areas throughout sub-Saharan Africa. Our species described below had not been discovered yet.
Axinidris can be distinguished amongst all other ants by what Snelling describes as “the strongly elevated medial carina at the summit of the propodeal declivity”, which simply means the large carbuncle-like bump at the back-end of the thorax, see illustration below.
We could not find a meaning for ‘axinidris’ and would appreciate some help here.

Axinidris lignicola (Snelling, 2007)
Grandfather’s wood ant

A small ant of about 3 mm, it is an even brown all over with paler legs, antennae and feet. Although the Dolichoderine sub-family of ants is a large one elsewhere in the world, in South Africa there are only about 13 indigenous species, of which only three are Axinidris. Our Axinidris lignicola is, however, the only indigenous Dolichoderine in the Western Cape. The only other members of the sub-family here are the invasive Argentine ant (Linepithema humile) and the White-footed ant (Technomyrmex albipes).
A. lignicola was first collected by Prins at Grootvadersbosch in 1985; Hamish Robertson collected it there again in 1995, and he described the colony as nesting “in centre of dead tree trunk c. 2.5 cm dia., 1 m above ground”. This and the Antwiki description quoted above led to Snelling, who published the first taxonomic description of the ant in 2007, giving it the name ‘lignicola’, meaning ‘wood dweller’.
We can only say ouch to that. In 2014 we collected our specimen, also at Grootvadersbosch, nesting in the ground in a clayey bank at the roadside, with nary a splinter of wood in sight. The colony was being vigorously attacked by Razor-jaw ants (Leptogenys intermedia), who were laying into the Axinidris with jaws and stings, and making off with their brood. The Axinidris were desperately retreating into the ground and this defence seemed to work, because when we passed by about an hour later the Leptogenys had gone and Axinidris were guarding the nest holes with mandibles agape.
It’s a rare ant and little is known about it, but it seems that Snelling’s specific name ‘lignicola’ might turn out to be as inappropriate as Linnaeus’s ‘Protea repens’ [= ‘creeping protea’] for our upright-growing sugarbush that can reach the size of a small tree.

We need to know whether Axinidris occurs elsewhere other than at Grootvadersbosch. If it does not, it should be listed as at least ‘Vulnerable’ in the Red Data list. It is not yet listed in the Encyclopedia of Life, which is odd after seven years!
There is more about the genus [but not our species; it was not yet described] in Shattuck’s revision, at 

Survive invasive species:
Linepithema humile       : Argentine ants       : unknown
Pheidole megacephala  : House ants            : unknown
Lepisiota sp.                  : Small Black ants    : unknown
Technomyrmex albipes : White-footed ants  : unknown
Anoplolepis gracilipes   : Yellow Crazy ants  : unknown

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