Amblyoponinae

The subfamily Amblyoponinae contains 11 genera which are found throughout most of the world, although they are more common in tropical and forested regions. It is represented in Australia by five genera which are most abundant and diverse in coastal and heavily forested areas, the subfamily being largely absent from the dry interior. Of these five, two (Amblyopone and Prionopelta) are found essentially world-wide, one (Mystrium) is found in Africa and from India to Australia, one (Myopopone) occurs from India to Australia while the last (Onychomyrmex) is restricted to Far North Queensland. Some species can be locally common and regularly encountered while others are rarely seen.

Nests are in soil under rocks or logs or in rotten wood. Colonies are often composed of numerous small nests scattered over a small area. In some cases large central chambers are absent and the colony consists of many small satellite nests containing a few workers together with a small amount of brood (larvae and pupae).

In most genera workers are cryptic predators in soil and leaf litter and are seldom seen foraging on the surface of the ground. Some species show a strong preference for centipedes while others will feed on a range of soft-bodied arthropods. It is common in some groups for workers to bring their larvae to food sources rather than attempt to move especially large prey back to the nest. When disturbed most will move slowly underground or remain motionless.

One genus, Onychomyrmex, differs significantly from others in this subfamily. These uncommon ants have an army-ant life style. They alternate between temporary bivouacs in protected sites on the ground and semi-permanent nests in soil or in rotten logs. Groups of workers forage by forming distinct raiding columns across the surface of the ground and some species are known to be specialist predators on centipedes.

Identification
The petiole with distinct front and top faces but without a separate rear face, the rear section of the petiole being attached to the gaster by its entire height. The upper surfaces of the petiole and gaster separated by at most a shallow impression. The upper plate of the second segment of the gaster (second gastral tergite) only weakly arched and located in the middle of the gaster, the rear-most part of the gaster pointing rearward or directly down. The broad attachment of the petiole to the gaster combined with the presence of a relatively straight gaster will separate species of Amblyoponinae from those of other subfamilies.

Boudinot (2015) - The supraaxial helcium serves to distinguish both female and male Amblyoponinae, excluding Apomyrma and Opamyrma, from the majority of the Formicidae. Besides occurrence in the amblyoponines, the supraaxial state of the helcium is only developed in Acanthostichus (Dorylinae) and male Proceratium (Proceratiinae), and weakly in the workers of Martialis (Martialinae) and the male of Tatuidris (Agroecomyrmecinae). Males of three amblyoponine genera (Bannapone, Concoctio, and Opamyrma) remain unknown.

Nomenclature
AMBLYOPONINAE [subfamily of Formicidae]
 * Amblyoponinae Forel, 1893a: 162 [as subfamily of Formicidae]. Type-genus: Amblyopone.
 * Amblyoponii: Emery, 1895c: 261 [as tribe of Ponerinae].
 * Amblyoponini: Ashmead, 1905b: 382 [emended spelling of suffix].
 * Amblyoponinae: Clark, 1951: 15 (in key) [as subfamily of Formicidae].
 * Amblyoponini: Brown, 1953c: 11 [as tribe of Ponerinae].
 * Amblyoponinae: Bolton, 2003: 41 [as subfamily of Formicidae].
 * Senior synonym of Examblyoponini: Brown, 1951: 102; of Reneini: Brown, 1953c: 11; of Ericapeltini and Onychomyrmicini: Bolton, 1994: 164; of Apomyrmini: Saux, Fisher & Spicer, 2004: 466.



Boudinot (2015):

Synapomorphies

The Amblyoponinae was diagnosed by Bolton (2003) based primarily on the female castes, while more recently Yoshimura & Fisher (2012a) diagnosed the males for the Malagasy region. Apomyrma and Opamyrma violate most of these characters; these violations are noted below. Synapomorphies of the Amblyoponinae from the two aforementioned resources are as follows, with respective pleisiomorphies presented in brackets:

1. Dentiform clypeal setae present on anterior clypeal margin (all adult castes) (note 1). [Dentiform clypeal setae absent.]

2. Metapleural gland orifice directed more-or-less posterodorsally (female castes) (note 2). [Metapleural gland orifice directed laterally.]

3. Helcium supraaxial, thus petiole situated high on abdominal segment III, petiole without distinct posterodorsal face and abdominal tergum III without distinct anterodorsal face (all adult castes) (note 3). [Helcium infraaxial.]

4. Petiole very broadly attached to abdominal segment III (all adult castes) (note 4). [Petiole narrowly attached to abdominal segment III.]

5. Helcial sternite very wide (all adult castes) (note 4). [Helcial sternite narrow.]

6. Abdominal segment IV tergosternal fusion present (all adult castes) (note 5). [Abdominal segment IV tergosternal fusion absent.]

7. Basivolsella with ventroapical process, near bases of cuspis and digitus (male) (note 6). [Apical process of basivolsella absent.]

Notes on synapomorphies 1. Generally present in males, although these setae may be difficult to ascertain or absent in very small species. Not present in any other extant ant taxon, although present in most †Sphecomyrminae. Apomyrma and Opamyrma workers and Apomyrma males lack dentiform clypeal setae (the male of Opamyrma is unknown); rather, the workers have dentiform setae on the labrum. The male of Apomyrma has a very reduced labrum which lacks dentiform setae.

2. Males with or, more often, without metapleural gland orifice. The metapleural gland of Apomyrma was not evaluated in this study due to insufficient magnification.

3. This corresponds to the third, fifth, and sixth amblyoponine synapomorphies of Bolton (2003). Apomyrma workers and males have infraaxial helcia, while the worker of Opamyrma has an axial helcium.

4. Petiole very narrowly attached in worker Apomyrma and Opamyrma. The petiolar conformation of the male of Apomyrma, though broad, still differs from that observed in Amblyoponinae (see note 5).

5. Reversed in Adetomyrma female castes and variable in males (Yoshimura & Fisher 2012a).

6. Character from Yoshimura & Fisher (2012a) and confirmed here via dissection of Amblyopone, Myopopone, Onychomyrmex, Paraprionopelta, and New World Stigmatomma.