62 
THE ARGENTINE ANT AND OTHER EXOTIC ANTS 
Iridomyrmex humilis Mayr 
Figs. 14. 
Hypoclinea humilis Mayr, Ann. Soc. Nat. Modena, iii, p. 164, 1868, ^ . 
Hypoclinea {Iridomyrmex) humilis Mayr, Verb. Zool. Bot. Ges. Wien, 
XX, p. 959, 1870, 5 . 
Iridomyrmex humilis, Emery, Zeitschr. f . Wiss. Zool., xlvi, p. 386, 1888. 
Iridomyrmex humilis, Newell, Jour. Econ. Entom., i, p. 28, 1908; 
ibidem, pp. 174-192, figs. 1-4, pis. 5 and 7, 1909, *5 9 S. 
Iridomyrmex humilis, Arnold, Ann. S. Afr. Mus., xiv (1), p. 145, pi. iv, 
figs. 41-4a, 1915, 2 3 . 
Worker. Length 2-3 mm. (Fig. 1). 
Brown, antennae and legs yellowish brown, mandibles yellowish. 
Smooth and somewhat shining, very finely, densely and superficially 
reticulate. Mandibles with small obsolete punctures. 
Hair very sparse, greyish, erect, confined to the mandibles, clypeus and 
apex of gaster. Pubescence greyish, very fine and close lying, abundant 
but not hiding the sculpture. 
Head longer than broad, much broader behind than in front, sides and 
posterior angles strongly convex, occipital border straight or feebly concave. 
Mandibles triangular, furnished with numerous small sharp teeth. Clypeus 
convex, high in the middle, anterior border projecting concave, the angles 
rounded. Frontal area indistinct. Frontal carinae as long as broad, not 
covering the antennal insertions in front. Scapes extend beyond the 
occipital border by one-fourth of their length; all segments of the funiculus 
longer than broad, gradually decreasing in length from first to tenth, apical 
as long as first. Eyes rather flatly convex, placed dorsally in front of the 
middle of the sides. Thorax almost two and one-fourth times longer than 
broad through the pronotum, slender. Pronotum one-fourth broader than 
long, strongly convex in all directions, pro-mesonotal suture sharply, but 
not deeply impressed. Mesonotum long and slender, not bordered on sides, 
strongly convex laterally, dorsum twice as long as broad; meso-epinotal 
suture deep and wide. Epinotum as long as broad, half as long as mesono- 
tum, convex in all directions; in profile the dorsum of pronotum and 
mesonotum evenly convex, highest at pro-mesonotal suture, epinotum short 
and convex, rounded into the declivity. Node thin, scale-like, convex trans- 
versely, top edge sharp. Gaster twice as long as broad. Legs long and 
slender. 
Female. (Dealated) Length 4- 5-5 5 mm. (Fig. 2). 
Colour and sculpture as in the worker. 
Hair sparse but more abundant than on the worker. Pubescence longer 
and much more abundant. 
Head very slightly longer than broad, slightly broader behind than in 
front, occipital border and sides straight, angles rounded. Mandibles 
larger, the teeth stronger and more numerous than in the worker. Scapes 
extend beyond the occipital border by one-fifth of their length. Eyes large 
and convex, occupying fully one-third of the sides. Ocelli large and convex, 
the two posterior at a sharp angle, facing sideways and outward. Thorax 
fully twice as long as broad. Pronotum almost hidden from above by the 
mesonotum, strongly convex in front. Mesonotum one-eighth longer than 
broad, sides and front strongly convex, parapsidal furrows sharply impressed. 
