Nine Bexar County 
Endangered Invertebrate Species

Beetles: Rhadine exilis / Rhadine infernalis / Batrisodes venyivi 

Harvestman: Texella cokendolpheri 

Spiders: Cicurina baronia / C. madla / C. venii / C. vespera / Neoleptoneta microps

Texas Endangered Invertebrate Species

Return to Texas Entomology

Original Document: 
[Federal Register: December 26, 2000 (Volume 65, Number 248)



Fish and Wildlife Service

Endangered and Threatened Wildlife and Plants; Final Rule to List Nine Bexar County, Texas Invertebrate Species as Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.


SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine nine cave-dwelling invertebrates from Bexar County, Texas, to be endangered species under the authority of the Endangered Species Act of 1973, as amended (Act). Rhadine exilis (no common name) and Rhadine infernalis (no common name) are small, essentially eyeless ground beetles. Batrisodes venyivi (Helotes mold beetle) is a small, eyeless beetle. Texella cokendolpheri (Robber Baron Cave harvestman) is a small, eyeless harvestman (daddy-longlegs). Cicurina baronia (Robber Baron cave spider), Cicurina madla (Madla's cave spider), Cicurina venii (no common name), Cicurina vespera (vesper cave spider), and Neoleptoneta microps (Government Canyon cave spider) are all small, eyeless or essentially eyeless spiders.

    These species (referred to in this final rule as the nine invertebrates) are known from karst topography (limestone formations containing caves, sinks, fractures and fissures) in north and northwest Bexar County. Threats to the species and their habitat include destruction and/or deterioration of habitat by construction; filling of caves and karst features and loss of permeable cover; contamination from septic effluent, sewer leaks, run-off, pesticides, and other sources; predation by and competition with nonnative fire ants; and vandalism. This action will implement Federal protection provided by the Act for these species. We based our decision on the best available information, including that received during public comment on the proposal to list these species.

EFFECTIVE DATE: The effective date of this rule is December 26, 2000.

ADDRESSES: The complete file for this rule is available for inspection, by appointment, during normal business hours at the Austin Ecological Services Field Office, 10711 Burnet Road, Suite 200, Austin, Texas 78758.

FOR FURTHER INFORMATION CONTACT: Alisa Shull, Supervisory Fish and Wildlife Biologist, Austin Ecological Services Field Office (telephone 512/490-0057; facsimile 512/490-0974).



    Rhadine exilis and Rhadine infernalis were first collected in 1959 and described by Barr and Lawrence (1960) as Agonum exile and Agonum infernale, respectively. Barr (1974) assigned the species to the genus Rhadine. Batrisodes venyivi was first collected in 1984 and described by Chandler (1992). Texella cokendolpheri was first collected in 1982 and described in Ubick and Briggs (1992). Cicurina baronia, Cicurina madla, Cicurina venii, and Cicurina vespera were first collected in 1969, 1963, 1980, and 1965, respectively. In 1992, Gertsch described these species. Neoleptoneta microps was first collected in 1965 and described by Gertsch (1974) as Leptoneta microps. The species was reassigned to Neoleptoneta following Brignoli (1977) and Platnick (1986).

   These nine invertebrates are obligate (capable of surviving in only one environment) karst or cave-dwelling species (troglobites) of local distribution in karst terrain in Bexar County, Texas. ``Karst'' is a type of terrain in which the rock is dissolved by water so that much of the drainage occurs into the subsurface rather than as runoff. The subsurface drainage leads to passages or other openings within the underground rock formations. Some of the features that develop in karst areas include cave openings, holes in rocks, cracks, fissures, and sinkholes.

   Habitat required by the nine karst invertebrate species consists of underground, honeycomb limestone that maintains high humidity and stable temperatures. The surface environment of karst areas is also an integral part of the habitat needed by the animals inhabiting the underground areas. Openings to the surface allow energy and nutrients, in the form of leaf litter, surface insects, other animals, and animal droppings to enter the underground ecosystem. Mammal feces provide a medium for the growth of fungi and, subsequently, localized population blooms of several species of tiny, hopping insects. These insects reproduce rapidly on rich food sources and may become prey for some predatory cave invertebrates (Service 1994). While the life habits of the nine invertebrates are not well known, the species probably prey on the eggs, larvae, or adults of other cave invertebrates.

   We funded a status survey (Veni 1994a; Reddell 1993) of all nine species through a grant to the Texas Parks and Wildlife Department (TPWD) under section 6 of the Act. Researchers obtained landowner permission to study and assess threats to 41 caves in north and northwest Bexar County, Texas. Landowners denied permission to access an additional 36 caves that biologists believed likely to contain species of concern. Researchers described all 77 caves, to some extent, before the status survey was conducted and some were already known to contain at least one of the nine invertebrates.

   During the status survey, the researchers made a collection of the invertebrate fauna at each cave studied, assessed the condition of the cave environment and threats to the species, and collected geological data. They used this information to prepare two reports. One report discusses the overall karst geography in the San Antonio region and the potential geologic and geographic barriers to karst invertebrate migration (on an evolutionary time scale) and limits to their distribution (Veni 1994a). The other report (Reddell 1993) details the fauna of each cave visited during the study and presents information obtained from invertebrate collections.

   Veni's (1994a) report delineates six karst areas (hereafter referred to as karst regions) within Bexar County. The karst regions he discusses are Stone Oak, UTSA (University of Texas at San Antonio), Helotes, Government Canyon, Culebra Anticline, and Alamo Heights. The boundaries of these karst regions are geological or geographical features that may represent obstructions to troglobite movement (on a geologic time scale) which has resulted in the present-day distribution of endemic (restricted in distribution) karst invertebrates in the San Antonio region.

   The harvestman Texella cokendolpheri, Robber Baron Cave harvestman, is known only from Robber Baron cave in the Alamo Heights karst region on private property. The cave entrance has been donated to the Texas Cave Management Association (George Veni, Veni & Associates, pers. comm. 1995), which will likely be interested in protection and improvement of the cave habitat. However, this cave is relatively large, and the land over and around the cave is heavily urbanized. The cave has also been subject to extensive commercial and recreational use (Veni 1988). No confirmed specimens of T. cokendolpheri were collected during the 1993 status survey, but one Texella harvestman collected at Robber Baron Cave since completion of the status survey, the species of which could not be positively identified, is highly likely to be T. cokendolpheri (James Reddell, Texas Memorial Museum, and Dr. Darrell Ubick, California Academy of Sciences, pers. comm. 1995).

   Batrisodes venyivi, the Helotes mold beetle, is known from only three caves in the vicinity of Helotes, Texas, northwest of San Antonio. Two of these caves are located in the Helotes karst region on private property. We do not have reliable information on the collection from the third cave. The collector of the specimen declined to give us a specific site collection record, but we believe it is located on private property.

   Rhadine exilis is known from 35 caves in north and northwest Bexar County. Twenty-one are located on Department of Defense (DOD) land in the Stone Oak karst region. The remainder are distributed among the Helotes, UTSA, and Stone Oak karst regions, while one location lies in the Government Canyon region. One of the non-DOD sites is located in a county road right-of-way, one is located in a state-owned natural area, and the remainder are located on private property. Ongoing efforts by the DOD to locate and inventory karst features on Camp Bullis and to document the karst fauna communities in caves on Camp Bullis resulted in discovery of 18 of the 35 caves mentioned above (Veni 1994b; James Reddell, pers. comm. 1997).    

   Rhadine infernalis is known from 25 caves. This species occurs in five of the six karst regions-- Helotes, UTSA, Stone Oak, Culebra Anticline, and Government Canyon. Scientists have delineated three subspecies (Rhadine infernalis ewersi, Rhadine infernalis infernalis, Rhadine infernalis ssp.), and described and named two of these in scientific literature (Barr 1960, Barr and Lawrence 1960). In a recent report, scientists characterized the third subspecies as distinct, but not named (Reddell 1998). Only three caves, all on DOD land, contain the subspecies Rhadine infernalis ewersi. Sixteen caves contain the subspecies Rhadine infernalis infernalis and lie in the Government Canyon, Helotes, UTSA, and Stone Oak regions. Six caves in the Culebra Anticline region contain the unnamed subspecies.

   Cicurina venii is known from only one cave, which is located on private property in the Culebra Anticline karst region. The species was collected in 1980 and 1983, but the cave itself was not initially described until 1988 (Reddell 1993). The cave entrance was filled during construction of a home in 1990. Without excavation, it is difficult to determine what effect this incident had on the species; however, there may still be some nutrient input, from a reported small side passage.

   Cicurina baronia, the Robber Baron cave spider, is known only from Robber Baron Cave in the Alamo Heights karst region. Although the cave entrance is owned and operated by the Texas Cave Management Association, it is located in a heavily urbanized area.

   Cicurina madla, Madla's cave spider, is known from six caves. One cave is within the Government Canyon karst region in Government Canyon State Natural Area, one is on DOD land, three are located in the Helotes karst region on private property, and one is located on private property in the UTSA karst region.

   Biologists have found Cicurina vespera, the vesper cave spider, in two caves. One cave is Government Canyon Bat Cave in the Government Canyon State Natural Area, and the other is a cave 5 miles northeast of Helotes. The location and name of this latter cave have not been revealed to us, but we believe it is located on private property.

   Neoleptoneta microps is known only from the Government Canyon karst region, from two caves within Government Canyon State Natural Area.

   In the course of conducting the 1993 status survey, Veni contacted landowners and requested access to as many caves as possible that were believed to be potential habitat for the nine invertebrates. It is possible that these species occur in some of the caves that could not be visited and that new locations of the nine invertebrates will be discovered in the future. Although these new discoveries may increase the number of locations where the species are found, they are expected to fall within the same general range and are expected to face the same threats as the known occurrences of these species. The listing of these species is not based on a demonstrable decline in the number of individuals or the number of known locations of each species, but rather on reliable evidence that each species is subject to threats to its continued existence throughout all or a significant portion of its range.


09 Mar 2005 - Mike Quinn / Texas Entomology