Leptanillinae

The subfamily Leptanillae contains 7 genera (4 of which are only known from males) and 42 described species. They are known from Africa and southern Europe east to Japan and Australia. No species are currently known from North or South America. Only a single genus (Leptanilla), with a single species (Leptanilla swani), is known from Australia. This is a rarely encountered species that is ground nesting and most often seen when males are found at lights at night.

The ant subfamily Leptanillinae represents one of the early branches of ant phylogeny, and until the recent discovery of Martialinae, the leptanillines were considered to be sister to all other ants under certain molecular phylogenetic analyses (Moreau et al. 2006, Brady et al. 2006, Rabeling et al. 2008). Brady et al. (2006) however, question the statistical rigor of this result and suggest alternative rooting of their tree that would result in Amblyoponinae and Leptanillinae emerging within a clade together with Agroecomyrmecinae. A close relationship of amblyoponines and leptanillines is also supported by some shared morphological and behavioral features (Brown et al. 1971, Gotwald & Lévieux 1972, Masuko 1986, 1990, Bolton 1990, Ward 1994, Brady et al. 2006, Yamane et al. 2008). The Leptanillinae are infrequently collected, they are small to tiny subterranean ants, and very little is known of their habits. Masuko (1990) studied the biology of Leptanilla japonica and showed that adult queens are incapable of taking food on their own, instead relying on larval haemolymph secreted through specialized abdominal structures. Recent collections of Leptanilla in Europe show that there is a high cryptic diversity of these ants in the Mediterranean region (López et al. 1994, Scupola & Ballarin 2009). López et al. (1994) reported collecting large numbers of Leptanilla thanks to a rarely employed method and searching in a habitat rarely explored by ant collectors, i.e., “lavage de terre” method and sandy banks of periodic streams. The subfamily is presently divided into two tribes, Anomalomyrmini Taylor, 1990 and Leptanillini Emery, 1910. A full list of subfamily, tribe, and generic references can be obtained from Bolton (2003) and the most recent catalogue of species has been provided by Bolton et al. (2007).



Worker of L. swani from Western Australia.



Male of L. swani from Queensland.

Identification
Workers of Leptanillinae are easily recognised by their small size, pale yellow colour, lack of eyes and slender bodies with a 2-segmented petiole. They may be confused with some small myrmicines (ants of the subfamily Myrmicinae). Myrmicines have frontal lobes which are expanded towards the sides of the head and partly or completely cover the bases of the antennae, while Leptanillinae lacks frontal lobes and has the antennae completely visible when viewed from the front. They are also similar to smaller Aenictus workers, but differ in being smaller and having 12 segments in the antennae (rather than 10 segmented).

Key to the genera of the subfamily Leptanillinae based on workers, slightly modified from Bolton (1994)

1. Mandible with 3-5 teeth, all located on distal half of masticatory margin. Maxillary palp with 1 segment. Metanotal groove vestigial to absent. Bulla of metapleural gland rounded, located behind level of propodeal spiracle. Metapleural trench absent. Clypeus very narrow in front of antennal insertions, the latter very close to the anterior margin of head. (Old World tropics and temperate regions) ... Leptanilla

- Mandible with more than 5 peg-like or saw-like teeth. Maxillary palp with 4 segments. Metanotal groove present, strong, and impressed. Bulla of metapleural gland elongate and narrow, running longitudinally below the propodeal spiracle. Metapleural trench present. Clypeus relatively broad in front of antennal insertions, the latter well back from the anterior margin of the head ... 2.

2. Mandible with peg-like teeth, sometimes with additional row of saw-like cuticular teeth along masticatory margin. Petiole with well differentiated posterior face. (Southern Palaearctic, Indo-Malayan) ... Protanilla

- Mandible without peg-like teeth, only saw-like cuticular teeth along masticatory margin. Petiole without differentiated posterior face (Indo-Malayan) ... Anomalomyrma

Distribution and Habitats
Australian distribution



Regional Genus Lists

 * Single species, Leptanilla swani