Bolton (2003) gives the following apomorphies of the Myrmicinae:

• Metapleural gland orifice a longitudinal slit or crescent, opening dorsally to posterodorsally, and not overhung by a cuticular flange or flap
• Petiole in posterior view with fused tergite and sternite equally convex, with their inner margins forming a circle
• Helcial tergite and sternite form a rough circle in frontal view, their apices meeting end to end, and the tergite not overlapping the sternite

Worker monomorphic, dimorphic, or polymorphic, often very strongly so; the soldier form having a very large head and strong mandibles. Frontal carinae nearly always separated, rarely close together; divergent or slightly convergent behind and rarely lobed anteriorly; usually the clypeus is wedged in between the frontal carinae; in the Metaponini and a few other forms the clypeus is not prolonged back, its posterior margin being rounded. Antennae from 4- to 12-jointed, often with a distinct club. Ocelli frequently absent in the ordinary worker, though in strongly dimorphic species they may still be more or less distinct in the soldier. Pedicel formed by the petiole and the postpetiole; very rarely ( Melissotarsus ) the postpetiole is nearly as wide as the basal segment of the gaster. Stridulatory organ usually present at the base of the gaster. Sting developed. Spurs of the middle and hind tibiae in the majority of cases simple or absent; pectinate in the Metaponini and Myrmicini only. Gizzard simple and tubular in most genera and of a very primitive type compared with the conditions in the Dolichoderinae, Camponotinae, and Pseudomyrminae.

 

Female usually winged and larger than the worker; in a few cases ergatoid; true dichthadiiform queens are not known, but in some parasitic genera ( Anergates , Anergatides ) the gaster of the fertile female becomes enormously distended.

 

Male usually with the copulatory armature partly exserted; entirely retractile in a few genera of the Solenopsidini only. Anal segment with cerci. In a few cases (as in certain species of Cardiocondyla ) ergatoid, wingless males are known, sometimes together with winged individuals. Antennae almost always 13-jointed, even when the worker and female have very few antennal joints (11-jointed in Stereomyrmex and Cataulacus ; 12-jointed in Metapone , certain Attini, Meranoplini, etc.).

 

The venation of the fore wing offers much diversity. In some genera the more primitive type is still retained, with a closed radial, two closed cubital cells, and a closed discoidal cell, but all degrees of reduction are met with. When there is only one cubital cell, the cubitus may be united with the radius by means of a long intercubitus(type of Solenopsis ) or the intercubitus may disappear, the cubitus and radius being fused in a spot or for some distance (type of Formica ).

 

Larva thick-bodied, orthocephalic, without exudatory papillae around the mouth. The body is, as a rule, abundantly covered with chitinous hairs of very different kinds; dorsal oncochaetae often present.

 

Nymphs never enclosed in a cocoon.

 

The Myrmicinae is the largest subfamily of ants, containing over 120 genera and many thousands of described species, races, and varieties, nearly as many as the other six subfamilies together. As would be expected, the taxonomic arrangement of this maze is exceedingly difficult and it is no wonder that such keen myrmecologists as Forel and Emery have not yet succeeded in reaching satisfactory results and are obliged to modify their views at every turn of the road. For practical and other reasons, have felt at liberty to change somewhat the classification proposed by Emery,1 though have followed him in the main. Have united the two tribes Solenopsidini and Pheidologetini, which pass repeatedly into each other and are merely separated by the shape of the radial cell (closed in the Pheidologetini; open in the Solenopsidini), a character the value of which seems to have been overrated by Emery. Have also accepted Forel's tribe Proattini and, furthermore, separated Stegomyrmex from the Dacetini as an independent tribe. The very peculiar genus Archaeomyrmex, recently discovered by Mann in the Fiji Islands, must also constitute a distinct tribe, which I have provisionally placed between the Myrmecinini and Meranoplini.

 

The habits in this subfamily offer no less diversity than the structure. The majority of the species are carnivorous or partly so; but many others are granivorous, the most prominent in this respect being the members of Messor and allied genera ( Novomessor , Veromessor , Oxyopomyrmex , Pogonomyrmex , many species of Pheidole , etc.). In these ants the nest often contains spacious granaries full of seeds. Many myrmicine ants are attracted by sugary substances such as are furnished by the nectaries of flowers or various extrafloral plant organs. Often, also, they attend aphids, coccids, psyllids, or leafhoppers for the sake of the honeydew they excrete. The New World "leaf-cutting" or "fungusgrowing " ants of the tribe Attini feed exclusively on the food-bodies ("bromatia") producd by fungi cultivated in their nests. There are also many cases of social parasitism which, in its most extreme form, has lead to the disappearance of the worker caste ( Wheeleriella , Epixenus , Epipheidole , Sympheidole , Epaecus , Anergates , Anergatides , and probably several other genera of which only males and females are known). Temporary social parasitism is probably the rule in some species of Aphaenogaster and in the Malagasy and Indomalayan subgenus Oxygyne of Crematogaster .

Barcode of Life Data Systems (BOLD) Stats
                                        

Specimen Records:	35,283	Public Records:	2,740
Specimens with Sequences:	23,812	Public Species:	325
Specimens with Barcodes:	20,703	Public BINs:	376
Species:	3,020
Species With Barcodes:	2,142

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Collection Sites: world map showing specimen collection locations for Myrmicinae