Amphisbaenians facultatively oviposit in ant and termite nests.

Oviposition-site selection is a key maternal decision in oviparous animals, involving trade-offs among incubation conditions, offspring performance, and maternal constraints. In amphisbaenians (worm lizards), a clade of highly specialized fossorial reptiles, oviposition has long been assumed to occur obligatorily in ant and termite nests, implying strong ecological specialization. Here, we re-evaluate this assumption using new field observations and a critical synthesis of published records. We describe a natural oviposition site of the smallhead worm lizard (Leposternon microcephalum) located in a soil cavity with no evidence of ants or termites and review 18 records from nine amphisbaenian species. Across species, eggs occur not only in ant and termite nests but also in subterranean cavities and decaying logs, indicating facultative rather than exclusive use of social-insect nests. A field inspection of 31 active ant nests during the reported oviposition season yielded no eggs or amphisbaenians. Additional evidence suggests some species excavate or modify underground chambers and that at least one species oviposits communally. These findings challenge the view of strict dependence on ant and termite nests and instead support oviposition-site choice in amphisbaenians as a flexible, context-dependent maternal behavior shaped by ecological trade-offs rather than rigid specialization. Standardized surveys across microhabitats and experimental tests of incubation environments are needed to clarify how availability, costs, and benefits interact to shape nesting decisions in fossorial reptiles.