Monomorium

Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., Bulletin of the American Museum of Natural History 45, pp. 39-269 : 161-162

Monomorium Mayr

The numerous species of this large and difficult genus are all small but form populous colonies, commonly with several fertile females.

The worker is usually monomorphic, in the subgenera Parholcomyrmex and Holcomyrmex tending more or less to dimorphism. Clypeus abrupt, not sharply marked off from the frontal area, with two longitudinal welts or ridges of ten bordering an impressed median area and terminating anteriorly in projections or teeth. (These welts are fused in the subgenus Syllophopsis ). Mandibles narrow, with few teeth. Maxillary palpi 1- to 2-jointed, labial palpi 2-jointed. Antennae 12-jointed, in a few subgenera 11-jointed, in one species ( M. decamerum ) 10-jointed, the club typically 3- jointed, but sometimes 4-jointed or indistinct. Promesonotal suture obsolete, the mesonotum more or less impressed at the mesoepinotal suture, the epinotum nearly always unarmed. Petiole pedunculate, with high node; postpetiole lower, rounded. Tibial spurs simple or lacking.

The female is always much larger than the worker, in some species wingless; in one Australian form (subapterum) with vestigial wings. Venation like that of Formica , with a discoidal cell, rarely without.

The male is smaller than the female, always winged, with 13-jointed antennae. Mesonotum usually without Mayrian furrows, genital appendages completely retractile.

The division of the genus was begun by Forel when he established the subgenus Martia . Emery1 has recently revised the grouping of species and has established several additional subgenera. Viehmeyer has also proposed a subgenus Corynomyrmex , and Santschi has since added the subgenera Syllophopsis and Isolcomyrmex . In a more recent paper,2 Santschi proposes to give Syllophopsis generic rank.

These subgenera (see the key, Part VII) may be arranged more or less according to their natural affinities in the following sequence:

1. Anillomyrma Emery

2. Martia Forel

3. Lampromyrmex Mayr (= Mitara Emery)

4. Chelaner Emery

5. Adlerzia Emery

6. Syllophopsis Santschi

7. Monomorium , sensu stricto

8. Notomyrmex Emery

9. Xeromyrmex Emery

10. Parholcomyrmex Emery

11. Isolcomyrmex Santschi

12. Holcomyrmex Mayr

13. Corynomyrmex Viehmeyer

The genus Monomorium , though cosmopolitan and of even wider distribution than Crematogaster since it occurs even in New Zealand and Patagonia, is represented by the great majority of species in the Old World. The Neotropical Region possesses only a few species of the typical subgenus Monomorium and the species of Martia , which are not known to occur elsewhere. The subgenera Notomyrmex , Adlerzia , and Chelaner are exclusively Australian. Anillomyrma is monotypic and known only from Ceylon. Isolcomyrmex and Syllophopsis are exclusively Ethiopian. Xeromyrmex is properly African but spreads into the Palearctic and Indian Regions. Holcomyrmex , Parholcomyrmex , and especially Monomorium , sensu stricto, are more widely distributed. Several of the species of Monomorium , sensu stricto, ( minutum , floricola , pharaonis ), Xeromyrmex ( salomonis ), and Parholcomyrmex ( gracillimum , destructor ) have been widely disseminated by commerce. The species of Holcomyrmex are harvesting ants of dry regions and this is true of certain Australian species which are allied to Parholcomyrmex , though I assign them to a new subgenus Protholcomyrmex (with the type Monomorium rothsteini Forel) to be described in a later paper.