Dorylus Fabricius

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: 41-42

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Dorylus Fabricius


Dorylus Fabricius  HNS 

Workers small or of medium size, without eyes or ocelli, highly polymorphic, constituting a series of forms which may be grouped as maximae, or soldiers, mediae and minimae. In the maxima the head is very large and usually broader in front than behind, the mandibles are long and narrow, with a small number of teeth on the inner border, the clypeus is very short and not marked off from the remainder of the head by sutures. Frontal carinae very short, erect, close together, not concealing the insertions of the antennae. Antennae short, inserted very near the mouth, 9- to 12- jointed, according to the species. Mediae smaller, with much smaller and shorter head, but the latter not narrowed in front; anterior border of clypeus more or less projecting in the middle over the mouth. Antennae as in the maxima. Minima very small, with the head narrowed anteriorly and the anterior border of the clypeus strongly projecting in the middle. Number of antennal joints reduced, seven being the minimum. Promesonotal suture distinct in all three forms of worker; mesoepinotal suture obsolete. Epinotum always unarmed. Petiole nodiform; postpetiole narrowed anteriorly, not or only indistinctly separated from the first gastric segment. Pygidium with a dorsal impression and terminating in three points. Posterior tibiae each with a pectinated spur.

Female very much larger than the worker, dichthadiiform, i. e. wingless, with long and voluminous abdomen. The head has the occipital lobes swollen and rounded, separated by a median longitudinal furrow. Eyes and ocelli absent, as in the workers. Clypeus as in the worker maxima, or soldier. Mandibles narrow, edentate. Antennae 11-jointed (12-jointed in the subgenus Dichthadia  HNS  ). Thorax segmented, but the mesonotum without differentiated scutum and scutellum; alar insertions vestigial. Petiole large, its posterior corners prolonged as blunt points. Postpetiole shorter than the first gastric segment, but not followed by a constriction. Pygidium and hypopygium gaping or separated so as to expose to view the eighth pair of abdominal spiracles, the anal segment and sting; the pygidium not impressed; the hypopygium surpassing the pygidium considerably and terminating in two lobes or appendages.

Male very large, with very large eyes and ocelli. Clypeus short, prolonged backward between the short, diverging frontal carinae. Mandibles edentate. Antennae 13-jointed; scape one-third or one-fourth as long as the funiculus which is filiform. Legs short; femora flattened, tibiae narrow. Wings with narrow, poorly defined pterostigma, placed near the apical third; radial cell elongate and open; one closed cubital cell, usually one recurrent nervure (two in the subgenus Rhogmus  HNS  and in some anomalies). Petiole nodiform or saucer-shaped, its concavity turned toward the postpetiole, the latter not separated from the gaster by a constriction. Gaster long, cylindrical or club-shaped. Pygidium rounded or split at the posterior border ( Rhogmus fimbriatus  HNS  ). Genital armature voluminous, completely retractile; annular lamina narrow; stipes and volsella simple; lacinia absent; subgenital plate deeply furcate.

Emery, who has devoted much careful study to the Dorylinae, divides Dorylus  HNS  into six subgenera ( Dorylus  HNS  , sensu stricto; Dichthadia  HNS  , Gerstaecker; Anomma  HNS  , Shuckard; Typhlopone Westwood  HNS  ; Rhogmus  HNS  Shuckard; Alaopone  HNS  Emery) mainly on the number of antennal joints and structure of the pygidium in the worker, the number of antennal joints and shape of the hypopygium in the female, and the shape of the; mandibles and petiole in the male. The genus (Map 4) occurs throughout Africa, India, Indochina, the Malayan Region, and Indonesia (Borneo, Java, Sumatra, and Celebes). All but one of the subgenera and most of the species are found in Africa; in Asia there are less than half a dozen species belonging to the subgenera Dichthadia  HNS  , Typhlopone  HNS  , and Alaopone  HNS  .

In the 'Genera Insectorum' (Dorylinae, 1910, p. 7) Emery makes the following statement on the ethology of the genus Dorylus:Apart from the subgenus Anomma  HNS  all the species of Dorylus  HNS  lead a subterranean life and come to the surface of the soil only on exceptional occasions, as, e. g., during inundations or in order to accompany the males when they take flight. Their societies are very populous. The soldiers and workers make subterranean expeditions for the. purpose of capturing insects and other small animals, and exploit manure piles, cadavers and probably also the nests of termites. The males come to lights at night. Search for the heavy and voluminous apterous females is beset with difficulties so that they are rare in collections. It may be noted that in all the specimens hitherto described, with the exception of the female of D. fimbriatus  HNS  described by Brauns, the terminal tarsal joints are lacking. I infer that the workers tear them off durin g the underground forays, while they are dragging the colossal queen by all her legs through the narrow galleries.