Worker small, mouomorphic, with 4-jointed labial and 6-jointed maxillary palpi, multidenticulatc mandibles, 12-jointed antenna- and entire or medially more or less emarginate clypeus. The node is reduced to an anterior thickening of the depressed or flattened petiole which is overlain by the first gastric segment; anus usually inferior. Gizzard short, calyx usually not divided into distinct sepals, feebly convex, covered with fine hairs, with the bulb almost exposed when viewed from the side.
The female is usually considerably larger than the male. The anterior wings have a single cubital cell, rarely two, and the discoidal cell is often lacking.
The male is commonly as small as the worker and has well-developed denticulate mandibles. Antennae filiform, with long scape, usually surpassing the posterior border of the head and as long as the three first funicular joints together. Thorax stout; mesonotum not. overhanging the pronotum. Genital appendages voluminous, the stipes with a large squamula and its free portion of variable shape. Wings as in the female, but the discoidal cell is often lacking in the smaller species.
Colonies of TapinomaHNS are usually populous and live in the ground or in the cavities of plants. The workers are timid and emit from their anal glands a strong odor like that of rancid butter ('Tapinoma-odor"). The genus is cosmopolitan and in the Nearctic Region reaches to rather high latitudes and altitudes (Map 32). One of the species. Tapinoma melanocephalumHNS , has been widely distributed by commerce throughout the tropics of both hemispheres. It is often a pest in shops and is known in Cuba as the "hormiga bottegaria."
Differe de TapinomaHNS par son epistome entier, sa tete deprimee, ses antennes epaisses, et surtout par le pedicule qui a une ecaille tres inclinee en avant, mais distincte et fort epaisse, arrondie au sommet. Comme il n'y a qu'un individu, je n'ai pu dissequer le gesier. Ce sous-genre se rapproche du S. G. DoleromyrmaHNS Forel, par l'existence d'une ecaille, mais celle-ci est tres mince chez DoleromyrmaHNS .
Workers monomorphic but size in some species variable. Antennae 12 segmented; palp formula 6, 4. Clypeus with front border truncate or incised. Petiole a small inconspicuous node overhung by the first gastral tergite. Queens as workers but with enlarged flattened alitrunk. Males have filiform thirteen segmented antennae with long scapes overreaching the occipital border. Head large relative to alitrunk. Genital armature with large prominent stipes.
This is a world-wide genus with most species found in the Indo-Australian and Ethiopian regions. There are several palaearctic species of which only one is indigenous north of latitude 50°. One or more of the smaller tropical species are cosmopolitan and sometimes establish in heated premises.
Figs. 20, 21. Iridomyrmex humilis (Mayr)HNS . - 20: worker in profile; 21: male in profile. Scale: 1 mm.