Kauai Cave Wolf Spider

Adelocosa anops

Description

Known in Hawaii as pe'e pe'e maka'ole, this cave-dwelling blind spider has a body length of 0.39-0.78 in (10-20 mm). The cephalothorax (fused head and thorax) is light brown or orange, with no eyes and long, translucent, orange bristly legs; the abdomen is dull white. All other members of this family have large, well-developed eyes, thus their common name.

Behavior

The no-eyed big-eyed wolf spider does not spin webs but actively stalks and overwhelms other invertebrates.

The species has a low reproductive capacity, laying only 15-30 eggs per clutch. The adult lifespan is at least six months.

Habitat

In its extremely limited cave ecosystem, the spider requires a permanent moisture source, constant 100% relative humidity, and stagnant air; temperatures between 75-80°F (24-27°C) are its preferred conditions.

Distribution

The no-eyed big-eyed wolf spider is known only from the deep zone of Koloa Cave, from where the type specimen was described, and from smaller populations in nearby segments of the same cave some 1.5 mi (2.4 km) away on the southeast coast of Kauai Island, in the Hawaiian group. These caves are lava tubes resulting from a single eruption of the Koloa volcanic series. This spider inhabits small cavities impenetrable to humans, as well as the caves themselves, but its distribution is limited to a single series of lava flows.

Threats

The greatest threats to this species are the withdrawal and pollution of groundwater and alterations on the surface for tourist facilities and urbanization. Water is already scarce, and natural water sources have been disrupted; some moisture in the caves now comes from surface irrigation of sugar cane. The spider and other cave invertebrates are extremely sensitive to desiccation, and a failure in water supply could be disastrous. Runoff from developments and urban areas can pollute the groundwater with pesticides and toxic chemicals. Agriculture has already ruined the largest lava cave in the area: it became covered with waste residue from sugar cane production. The introduction and spread of invertebrate disease organisms for biological control of soil pests may decimate the endemic cave fauna. The elimination of plant roots by destruction of the surface vegetation removes an important food source from the habitat. Human visitors may affect cave habitats by trampling, littering, smoking, vandalizing, destroying tree roots, or altering the microclimate. Until recently, the two Koloa caves were Civil Defense shelters and are well-known to local people. Although the spiders would probably survive in remote crevices, human interference could destroy those spiders accessible to scientists and the public.

Conservation and Recovery

Some beneficial cooperation has been obtained from landowners in the area, and limited funds have been acquired, which have permitted intermittent surveys and research. Of the many small caves in the area, only four segments in two areas have suitable moisture and microclimates and harbor small populations of the spider. Plans have been initiated to establish reserves for these caves; two are slated for protection within a golf course development, and the Koloa caves are to be protected within a new housing development. Another cave segment has been protected and efforts made to attract the spider.

The largest and most stable populations of the spider occur in Koloa Cave No. 2, and formal reserve status for all of this cave should be established. Long-term monitoring of the populations within the two reserve caves on resort property is necessary to ensure that the size of these reserves is adequate for the survival of the species. Management regulations need to be developed and should include provisions for limiting access to the caves and restrictions on the type of modifications allowed on the surface near and above the caves.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 14 January 2000. "Endangered and Threatened Wildlife and Plants; Final Rule To List Two Cave Animals From Kauai, Hawaii, as Endangered." Federal Register 65(10): 2348-2357.