Nine Bexar County
Endangered Invertebrate Species
exilis / Rhadine infernalis /
Spiders: Cicurina baronia / C.
madla / C. venii / C.
Endangered Invertebrate Species
Return to Texas
Register: December 26, 2000 (Volume 65, Number 248)]
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
Endangered and Threatened Wildlife and
Plants; Final Rule to List Nine Bexar County, Texas Invertebrate Species as
AGENCY: Fish and Wildlife Service,
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,
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
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
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
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).
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.
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).
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.
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
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.
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.
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 -
/ Texas Entomology