Cataulacus mckeyi Snelling
Type location Cameroun
(Snelling, 1979a, illustrated with SEM photographs) collected near Lake
Tissongo, Douala-Edea Reserve, by Doyle McKey; workers with males and
females - see paratypes at http://www.antweb.org/specimenImages.do?code=casent0217829 .
Snelling's description (1979a) is at
WORKER - TL ca 3.3 mm, HW ca 0.96 (Gaume &
McKey,1999); diagnostic features as in key.
From Snelling's (1979a: 5, illustrated, all forms) description - TL
3.58-4.04, HL 0.86-0.94. Head about as long as broad; head and alitrunk
dorsa with abundant erect, flattened hairs; and hairs arising from
punctures wider than the hairs. Dorsum of head with fine rugoreticulum,
fairly shiny, puctate especially on vertex. Alitrunk dorsum weak
rugoreticulum, but meshes faint so that longitudinal rugae dominate.
First gastral tergite moderately shiny with fine medial longitudinal
This ant is an obligate inhabitant of the ant-plant Leonardoxa
africana africana (Caesalpinaceae; denoted as ssp L4 or T4 in
earlier papers) in Cameroun . This rain forest understorey tree is a
very specialised myrmecophyte, which has evolved so as to have an
obligate mutualistic relationship with Petalomyrmex
phylax (see McKey studies for
more details). Some 75% of all the trees are occupied by P. phylax
but the remainder are occupied by Cataulacus mckeyi. Whereas P.
phylax actively patrols all immature leaves, removing or dislodging
potential small insect herbivores, Cat. mckeyi has smaller and
much less active colonies doing little or nothing to protect the young
leaves. Both ant species, however, get most of their sustenance from
extra-floral nectaries on mature leaves. Thus, as Cat. mckeyi
appears to convey no real benefit on the host tree, it is regarded as a
parasite of the Leonardoxa-Petalomyrmex relationship. Gaume
& McKey (1999) knew of no other plant-ant to be an obligate
non-protective parasite of its sole host-plant species.
As the host tree is found only in a limited area of
coastal rain forest in Cameroun (approximately that shown as the "area
of 2001 collections" in Map 7, the
geographical range of the ant is pretty well known - from ca 4°28'N to
2°34'N, and no further than 10°25'E.
In its host Cat. mckeyi makes entrance holes
into the domatia of a precise size such that the hole can be blocked by
the head of a single worker.
photomontage is of a specimen sent to me by Professor McKey. The
flattened body form and very dense short hairs, plus the block-like
pedicel segments are distinctive. The head is convex with no obvious
denticles and large eyes, plus all over dense spiculation. The
specimen, however, is somewhat smaller than Snelling. Snelling did not
give any details of colour and his SEM photographs are far from clear.