Leptanillinae

The subfamily Leptanillae contains 6 genera, 2 of which are known only from males. These ants occur 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.

Identification
Workers of Leptanillinae are 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. Leptanillinae lack frontal lobes and have 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.

Generic Key
Key to the genera of the subfamily Leptanillinae based on Xu (2012). This key is for workers and does not include two genera (Phaulomyrma and Yavnella) that are only known from males.

1

 * Mandibles subtriangular, masticatory margins shorter than or subequal to inner margins, the former with 3-5 teeth. Antennal insertions very close to the anterior margin of the head. Body very slender (Old World Tropics and Temperate Regions) . . . . . Leptanilla


 * Mandibles elongate, masticatory margins much longer than inner margins, the former with many more than 5 minute saw-like denticles or slender peg-like teeth. Antennal insertions well behind the anterior margin of the head. Body relatively robust . . . . . 2

2

 * Masticatory margins of mandibles with many minute saw-like denticles. In profile view, promesonotum high and strongly convex. Metanotal groove deeply depressed. Petiole broadly attached to the postpetiole (Indo-Australian) . . . . . Anomalomyrma


 * Masticatory margins of mandibles with many slender peg-like teeth. In profile view, promesonotum low and weakly convex. Metanotal groove shallowly notched. Petiole narrowly attached to the postpetiole . . . . . 3

3

 * In profile view, mandibles massive, lateroventral margin furcated and with 2 teeth. Postpetiole broadly attached to anterior face of gaster. Ventral face of postpetiole concave. In dorsal view, anterior margin of gaster deeply concave (Oriental) . . . . . Furcotanilla


 * In profile view, mandibles slender, lateroventral margin not furcated and without teeth. Postpetiole narrowly attached to anterior face of gaster. Ventral face of postpetiole convex. In dorsal view, anterior margin of gaster almost straight (Southern Palaearctic, Oriental, and Indo-Australian) . . . . . Protanilla

Distribution and Habitats


Regional Genus Lists

 * Single species, Leptanilla swani