The Tooth cave spider (Neoleptoneta myopica) is a 1/16 inch (1.6 mm) long arachnid considered to be the smallest known invertebrate. It is native to Texas (USA) and is considered an endangered species.

This spider has a pale-cream color and very long legs. The spider has six "obsolescent" eyes; they are nearly absent and have no dark pigment. The Tooth cave spider is a sedentary aerial spider that hangs from a small tangle or sheet web on long, thin legs. It preys on tiny microarthropods.

The tooth cave spider lives on cave walls and ceilings of the Edwards Plateau in Travis County, Texas and near Austin. Destruction of these cave habitats in urban areas is the primary cause of its endangered status.

Its reproductive habits, description of nurturing by parents and population are as yet undescribed.