page_title: Leptanilla japonica
section_title: Morphology and description
hierarchical_section_title: Leptanilla japonica / Morphology and description
caption_attribution_description: English: A drawing of the ventral view of the stenocephalic head of a final instar larva of the ant species Leptanilla japonica.
context_page_description: Leptanilla japonica is an uncommon highly migratory, subterranean ant found in Japan. They are tiny insects, with workers measuring about 1.2 mm and queens reaching to about 1.8 mm, and live in very small colonies of only a few hundred individuals at a time Its sexual development follows a seasonal cycle that affects the colony's migration and feeding habits, and vice versa. L. japonica exhibits specialized predation, with prey consisting mainly of geophilomorph centipedes, a less reliable food source that also contributes to their high rate of nest migration. Like ants of genera Amblyopone and Proceratium, the genus Leptanilla engages in larval hemolymph feeding, with the queen using no other form of sustenance. LHF is an advantageous alternative to the more costly cannibalism. Unlike any other ant, however, members of Leptanilla, including L. japonica, have evolved a specialized organ dubbed the “larval hemolymph tap” that reduces the damage LHF inflicts on the larvae. LHF has become this species' main form of nutrition.
context_section_description: L. japonica is subterranean, migratory, and a very small ant, measuring only 1.2 mm for workers and 1.8 mm for queens. Workers are yellow and blind.
  Larvae are smaller, closer to 0.8 mm, with specialized features used in feeding and nest migration. They have relatively large bodies covered in minute hairs and their hairless heads are quite small, a characteristic called stenocephaly; this feature evolved to help large groups of larvae feed on one centipede body at once Their mandibles also developed to help them feed; they are directed outwards and armed with sharp teeth, enabling the larvae to eat without assistance from the workers. Another unusual structure lies on the ventral or bottom side of the first segment of the larvae's thorax, also called their prothorax; workers grab on to this with their lower mouthparts, which are distinct from their mandibles, when transporting larvae during migration. The “larval hemolymph tap” is the Leptanilla larvae's most unusual feature and was formerly thought to be a spiracle. Their spiracles are simply very, very small. The “tap” consists of a duct that connects to their hemolymph, with an opening surrounded by a small hairless area on the fourth abdominal segment. This specialized organ greatly facilitates LHF.
  Colonies are very small, with average worker populations numbering only 100-200 individuals. Research suggests that, based on the ant's cyclical development and reproduction, worker populations are renewed annually, with most workers living for about one year.
  When migrating either to prey or a new nest site, workers attach their lower mouthparts to the larvae's prothoracic structure and carry them along their body, ventral side to ventral side, with the larva's head pointing forwards. When agitated, however, workers will also simply grab the larva behind the head with their mandibles and drag them.
  Queens are larger than workers; they have eyes, but no wings. The posterior or last segment of their abdomen, also called their gaster, is very large in proportion to the rest of their bodies.
  Males measure roughly 1.3 mm in size, only a little bigger than the workers, and are unusual in having hairy eyes. They are the only caste with wings, albeit rather small wings. One wing actually consists of two parts: the forewing is larger and has veins; the hindwing is much smaller with no veins. Their mandibles are also different from the females’; whereas the workers and queens mandibles are prominent and mobile, the males’ mandibles are little more than small lobes held close to their head. Male ants of this species have been difficult to find in conjunction with workers and queens, and thus their behavior has not been observed and recorded as extensively as that of the females.
caption: The larva's stenocephalic head with the elaborate prothoracic structure below the mandibles and other mouthparts.
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