Tooth Cave Spider

Neoleptoneta myopica

Description

The Tooth Cave spider, Neoleptoneta myopica, has a very small, pale-colored body up to 0.1 in (0.5 cm) in length with relatively long legs. Although it lives in near-total darkness, reduced eyes are present. The spider's body consists of two main parts, the prosoma and the abdomen, which are connected by a narrow stalk, the pedicel. The prosoma provide locomotion and food intake while the abdomen provides digestion, circulation, respiration, excretion, reproduction, and silk production. Attached to the carapace is one pair of biting chelicerae and one pair of leg-like pedipalps situated in front of four pairs of walking legs. In mature males the pedipalps are modified into copulatory organs.

Behavior

This arachnid is highly sedentary, spinning webs from the ceiling and walls of Tooth Cave. It feeds on insects that inhabit the cave or happen to enter it. The victims are subdued by the spider's venom, then crushed with the chelicerae while being bathed with quantities of digestive fluid from the maxillary glands. The softer parts of the prey are broken down and predigested in a liquid state, and this liquid is sucked into the stomach. As the prey is rolled and chewed, it becomes smaller and smaller until only a small ball of indigestible material remains.

The spider's reproductive biology has not been well studied. It is nonmigratory, remaining sedentary over its lifetime.

Habitat

The Tooth Cave spider occurs in a single population in one small, dry cave. It depends on the infiltration of groundwater, which makes it vulnerable to chemicals that may seep into the groundwater supply.

Distribution

The Tooth Cave spider is endemic to Tooth Cave, which is located northwest of Four Corners in Travis County near the city of Austin, Texas.

The number of Tooth Cave spiders is unknown. While only a few specimens have ever been collected, this may reflect the limited size of the habitat rather than a declining population. Tooth Cave is the sole known habitat for this arachnid.

Threats

The Tooth Cave spider depends on some infiltration of groundwater, and a disruption of flow due to development, such as construction for a proposed pipeline, would pose an immediate threat. Likewise, the seepage of urban runoff into the ground is likely to degrade water quality.

Conservation and Recovery

At time of the Karst Invertebrates Recovery Plan publication, the Tooth Cave spider had a U.S. Fish and Wildlife Service (FWS) recovery priority of 2C, indicating a species with a high degree of threats, high potential for recovery, and in conflict with construction or development projects of other forms of economic activity.

Contact

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 1306

Albuquerque, New Mexico 87103-1306
Telephone: (505) 248-6911
Fax: (505) 248-6915
http://southwest.fws.gov/

References

Gretsch, W. J. 1974. "The Spider Family Leptonetidae in North America." The Journal of Arachnology 1: 145-203.

Reddell, J. R. 1984. "Report on the Caves and CaveFauna of the Parke, Travis County, Texas." Unpublished Report to the Texas System of Natural Laboratories.

U. S. Fish and Wildlife Service. 16 September 1988. "Determination of Five Texas Cave Invertebrates to Be Endangered Species." Federal Register 53 (180): 36029-36033.

U. S. Fish and Wildlife Service. 1994. "Recovery Plan for Endangered Karst Invertebrates in Travis and William Counties, Texas." U.S. Fish and Wildlife Service, Albuquerque.