Leptanilla

Hita Garcia, Wiesel and Fischer (2013) - The more than 40 species of Leptanilla (Bolton, 2012) are largely distributed in the Old World tropics and subtropics (Baroni Urbani, 1977; Bolton, 1990; Lopez et al., 1994). Baroni Urbani (1977) revised the genus on a global basis but today there are numerous undescribed species. Sampling methods that specifically target hypogaeic insects (Normand, 1911; Lopez et al., 1994) are also likely to discover more species of these cryptic ants. The members of this genus are all very small, pale, subterranean ants that are rarely collected, especially both worker and queen castes. Leptanilla species nest and forage in the ground, and seem to be specialised predators of geophilomorph centipedes (Masuko, 1990). Additionally, the queens of some species are known to feed on their larvae, but unlike amblyoponine queens they do not damage the larval integument. Instead the larvae possess a specialised duct organ on the fourth abdominal segment from which the queens can gain the larval haemolymph (Bolton, 1990; Masuko, 1990). Leptanilla displays several behavioural similarities to army ants since all known queens are dichthadiiform, several species are known to be migratory, and foraging is performed in groups.

Identification
Workers of Leptanilla are minute and pale, a reflection of their subterranean life-history. Many species are known only from males. Queens and males have a petiole, while workers have a petiole and postpetiole. Zu (2002) provided a key to the genera of the Letpanillinae. The set of characters that separate this genus from the other genera in the subfamily with workers (two genera are only known from males): 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.

Biology
Vietnam (Eguchi et al 2014) - Leptanilla spp. inhabit woodland habitats including well-developed forests and forest edges, and lowland and montane forests. Their nests are found under stones and wood fragments. Small dead centipedes being eaten by many larvae are sometimes found inside a nest chamber. Leptanilla spp. are rare in Vietnam, but Leptanilla sp. eg-1 is relatively frequently found in montane forests at the foot of Mt. Fan Si Pan (Sa Pa, Lao Cai).

Nomenclature

 *  LEPTANILLA [Leptanillinae: Leptanillini]
 * Leptanilla Emery, 1870: 196. Type-species: Leptanilla revelierii, by monotypy.
 * Leptanilla senior synonym of Leptomesites: Baroni Urbani, 1977c: 433.
 * LEPTOMESITES [junior synonym of Leptanilla]
 * Leptomesites Kutter, 1948: 286. Type-species: Leptomesites escheri, by original designation.
 * Leptomesites junior synonym of Leptanilla: Baroni Urbani, 1977c: 433.

Male
Ogata et. al. (1995):

(1) Head longer than broad, with subparallel sides and rounded posterior corners.

(2) Eyes medium in size, situated anteriorly.

(3) Mandibles reduced, forming non-opposable lobes.

(4) Palp formula 1,1.

(5) Antennal insertions close to anterior margin of cranium.

(6) Antennal insertions exposed; antennae with l3 segments.

(7) Pronotum elongate with concave posterolateral portion.

(8) Mesoscutum long and narrow, not overhanging pronotum, with arched dorsal surface.

(9) Notauli absent on mesoscutum.

(10) Mesoscutellum less raised, not overhanging metanotum.

(11) Forewing lacking pterostigma and with poor venation (Sc + R + Rs).

(12) Hindwing narrow, lacking any veins.

(13) Middle tibia with one small apical spur; hind tibia with two small apical spurs.

(14) Metapleural gland absent.

(15) Propodeum cylindrical, with arched dorsal surface.

(16) Petiole isolated, subglobous without anterior peduncle.

(17) Third abdominal segment not forming postpetiole.

(18) Cerci absent.

(19) Hypopygium small and broad, sometimes bifurcate posteriorly.

(20) Basal ring small, thin, weakly sclerotized.

(21) Digitus simple and elongate.

(22) Apical portion of parameres thin, flattened, dorsally protruding, sometimes armed with small teeth.

(23) Aedeagal plates flattened, often broad, without serrate ventral margin.