Ectatomminae

The subfamily Ectatomminae is represented in Australia by two genera, Gnamptogenys and Rhytidoponera. Gnamptogenys is uncommon and restricted to Cape York Peninsula, Queensland while Rhytidoponera is one of the most common groups of ants in Australia. Gnamptogenys nests in rotten wood while Rhytidoponera generally nest in soil, with some species in rotten wood.

Nomenclature
ECTATOMMINAE [subfamily of Formicidae]
 * Ectatommii Emery, 1895j: 767 [as tribe of Ponerinae]. Type-genus: Ectatomma.
 * Ectatomminae: Bolton, 2003: 45, 172 [as subfamily of Formicidae].

Bolton 2003:

The poneromorph subfamilies

Subfamilies Amblyoponinae, Ectatomminae, Heteroponerinae, Paraponerinae, Ponerinae, Proceratiinae.

Diagnosis Orifice of metapleural gland never concealed by a dorsally located cuticular flange or flap. Propodeal lobes present. Waist of one segment (petiole) that is separated posteriorly from abdominal segment III (first gastral) at least by a constriction (note 1). Helcium sternite retracted, overlapped by the tergite (note 2) (also in male). Abdominal segments III and IV with tergosternal fusion (also in male) (note 3). Abdominal segment IV with presclerites and usually a girdling constriction present between the presclerites and postsclerites (note 4) (also in male). Spiracles of abdominal segments V - VII concealed by posterior margins of preceding tergites. Sting present, usually strongly developed. [Synopsis, p. 153.]

Notes (1) In almost all poneromorphs abdominal segment III varies from slightly larger than IV to slightly smaller than IV. However, in Paraponerini and a few species of Proceratiini segment III is markedly reduced with respect to IV and may be termed sub-postpetiolate. See also notes under myrmicomorphs. (2) Helcium sternite is convex and not overlapped by the tergite only in Discothyrea (Proceratiini). In this respect Discothyrea resembles the dorylomorphs but otherwise their morphologies are very different; the similarity of the helcium is presumed to be by convergence. (3) For distribution of tergosternal fusion of abdominal segment III throughout the family see under dorylomorphs (note 3). Of all the poneromorphs only the monotypic Malagasy amblyoponine genus Adetomyrma lacks tergosternal fusion on abdominal segments III and IV. Whether this is plesiomorphic or a reversal from a previously fused state remains under debate (see discussion in Ward, 1994). It is by no means definite that tergosternal fusion of abdominal segment IV represents a poneromorph synapomorphy. Outside the poneromorphs this fusion is restricted to Tatuidris (Agroecomyrmecini) and Ankylomyrma (Ankylomyrmini). (4) The girdling constriction is usually apparent but in the amblyoponine Adetomyrma sharply differentiated presclerites are absent on abdominal segment IV. In Ponerini the character is variously reduced or lost in such genera as Asphinctopone and Phrynoponera, and in some individual species or species groups within larger genera such as Leptogenys, Anochetus, Odontomachus, Pachycondyla, and also in Simopelta.

Comments (i) The traditional large subfamily Ponerinae is abandoned here and its former components are regrouped as six independent subfamilies. This radical reassessment is because it has become apparent in recent years that the old and long-established concept of a single "subfamily Ponerinae" is no longer defensible. Regarding all the poneromorphs as a single subfamily has probably held back the generation of an accurate phylogeny in this part of Formicidae because "Ponerinae" as a terminal taxon could not be defined in a precise manner. (ii) Despite the lack of an unequivocal synapomorphy the six subfamilies together are treated here under the unofficial group-name poneromorph, to distinguish them from other obvious and often better delimited assemblages of subfamilies, such as the dorylomorphs and formicomorphs. Subfamily Ponerinae is now restricted to tribes Ponerini + Platythyreini + Thaumatomyrmecini.

ECATOMMINAE

Diagnosis With characters of poneromorph subfamilies. Clypeus broadly inserted between frontal lobes; anterior clypeal margin with a narrow lamellar apron (note 1). Outer margins of frontal lobes not pinched in posteriorly. Torulus not completely fused to frontal lobe. Promesonotal suture fully mobile to fully fused. Metapleural gland orifice in profile a longitudinal to oblique curved slit or narrow crescent, bounded below by a convex rim of cuticle that directs the orifice dorsally to posterodorsally (note 2). Metacoxal cavities open, either fully open or with endpoints of annulus acute and almost touching. Mesotibia and metatibia each with 0 - 1 spur (1 - 2 in males). Pretarsal claws with a preapical tooth (note 3). Petiole with or without tergosternal fusion (note 4); laterotergites indistinct to absent. Helcium projects from about the midheight of the anterior face of abdominal segment III; no high vertical anterior face to abdominal segment III above the helcium. Stridulitrum absent or present on pretergite of abdominal segment IV (note 5). Antenna with 12 segments (13 in male). [Synopsis, p. 172.]

Notes (1) Also present in Heteroponerini and may be a synapomorphy of the two groups; the feature is also encountered among several groups of Myrmicinae. (2) Cuticle below the slit-like gland orifice often bears dorsally directed guard-hairs. The structure of the orifice appears identical to that seen in basal Myrmicinae and may be a synapomorphy of the two groups. (3) In Ectatomma, Rhytidoponera and almost all Gnamptogenys species the preapical tooth on the inner margin of each pretarsal claw is conspicuous. In a very few mainly minute, cryptic Gnamptogenys species the extra tooth is small, basal and inconspicuous; in a couple of Gnamptogenys species and in all Typhlomyrmex species it appears to be restricted to the foreleg claws alone. Preapical tooth is present on the pretarsal claws in males of all genera. (4) The petiole shows tergosternal fusion in Ectatomma, Gnamptogenys and Typhlomyrmex. In Rhytidoponera the tergite and sternite are tightly attached but are not fused. (5) A stridulitrum is entirely absent in Typhlomyrmex and Gnamptogenys but is present on the pretergite of abdominal segment IV in Ectatomma. In Rhytidoponera it is present either on the pretergite or on the presternite of abdominal segment IV. In the entire Formicidae the presence of a stridulitrum on sternite IV is known only here and in Nothomyrmecia, which certainly represents a parallelism.

Comments (i) Ectatomminae is dimorphic as regards the jugal lobe of the hindwing. It is present in alates of Ectatomma but absent in those of Rhytidoponera, Gnamptogenys and Typhlomyrmex. (ii) According to Hashimoto (1996) Ectatommini and Myrmicinae share the development of a cuticular lobe mid-anterodorsally on the pretergite of abdominal segment III, which is absent in all other ants. If universal this would constitute a powerful synapomorphy for the two groups. However, his sample size is small and lacks some critical components (for example Heteroponerini, Paraponerini, Typhlomyrmecini); a much wider survey is required.