Heterelmis comalensis - Bosse, Tuff, and Brown, 1988
Comal Springs Riffle Beetle
Taxonomic Status: Accepted
Related ITIS Name(s): Heterelmis comalensis Brown (TSN 193733)
Unique Identifier: ELEMENT_GLOBAL.2.106789
Element Code: IICOL5B020
Informal Taxonomy: Animals, Invertebrates - Insects - Beetles - Other Beetles
 
Kingdom Phylum Class Order Family Genus
Animalia Mandibulata Insecta Coleoptera Elmidae Heterelmis
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: Bosse, L. S., D. W. Tuff, and H. P. Brown. 1988. A new genus an species of Heterelmis from Texas (Coleoptera:Elmidae). Southwestern Naturalist. 33:199-203.
Concept Reference Code: A88BOS01EHUS
Name Used in Concept Reference: Heterelmis comalensis
Conservation Status
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NatureServe Status

Global Status: G1
Global Status Last Reviewed: 19May2009
Global Status Last Changed: 24Sep1996
Rounded Global Status: G1 - Critically Imperiled
Reasons: Restricted to two springs in Texas. This aquifer-dependent species is subject to population reduction, or possible extinction, if water quality or quantity is decreased due to drought or over-pumping.
Nation: United States
National Status: N1 (19May2009)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Texas (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (18Dec1997)
Comments on USESA: Critical Habitat was designated in 2007 (USFWS, 2007).
U.S. Fish & Wildlife Service Lead Region: R2 - Southwest

NatureServe Global Conservation Status Factors

Range Extent: <100 square km (less than about 40 square miles)
Range Extent Comments: Known from Comal Springs spring runs 1, 2, and 3 in Comal County, Texas (entire length of spring is 4 km); and from a single specimen in San Marcos Springs, Hays County, Texas (Bosse et al., 1988; USFWS, 1994).

Area of Occupancy: Unknown 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 1 - 5
Number of Occurrences Comments: Only known from two spring systems, Comal Springs in Comal County, Texas and San Marcos Springs in Hays County, Texas. Nothing is known about whether this species may have historically ranged in other springs that are now dry almost all the time, such as San Pedro Springs and San Antonio Springs (The Edwards Aquifer Website, accessed May, 2009).

Population Size: 50 - 2500 individuals
Population Size Comments: Bosse et al. (1988) collected 38 specimens from Comal Springs. Only one specimen was collected from San Marco Springs (USFWS, 1994).Gibson et al. (2008) collected 37 specimens from Comal Springs.

Number of Occurrences with Good Viability/Integrity: Unknown

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: The primary threat to this species is the potential failure of spring flow due to drought or excessive groundwater pumping, which could result in loss of aquatic habitat (USFWS, 2007). According to Bowles et al. (2003), although this species persisted at Comal Springs in the 1950s despite drought conditions, it is aquatic and requires water to complete its individual life cycle. The mechanism by which it survived the drought and the extent to which its population was negatively impacted are uncertain. These species are not likely adapted to surviving long periods of drying (up to several years in duration) that may occur in the absence of a water management plan for the Edwards Aquifer that accommodates the needs of these invertebrates (The Edwards Aquifer Website, accessed May, 2009).

According to the Edwards Aquifer Website, it is likely that the effect of natural droughts in south central Texas will increase in severity because of the large increase in human groundwater withdrawals. Many possible effects of reduced springflow exist. These include changes in the chemical composition of the water in the Aquifer and at the Springs, a decrease in current velocity and corresponding increase in siltation, and an increase in temperature and temperature fluctuations in the aquatic habitat (McKinney and Watkins, 1993).

Another threat to the habitat, according to the Edwards Aquifer Website, is the potential for groundwater contamination. Pollutants of concern include those associated with human sewage, leaking underground storage tanks, animal/feedlot waste, agricultural chemicals (especially insecticides, herbicides, and fertilizers) and urban runoff (including pesticides, fertilizers, and detergents).

Also, pipeline, highway, and railway transportation of hydrocarbons and other potentially harmful materials in the Edwards Aquifer recharge zone and its watershed, with the attendant possibility of accidents, present a particular risk to water quality in Comal and San Marcos Springs. Comal and San Marcos Springs are both located in urbanized areas (The Edwards Aquifer Website, accessed May, 2009).




Short-term Trend: Unknown

Long-term Trend: Unknown
Long-term Trend Comments: No long-term trends as this species was described in 1988.

Intrinsic Vulnerability: Unknown

Environmental Specificity: Unknown

Other NatureServe Conservation Status Information

Inventory Needs: Population size unknown at both sites.

Protection Needs: The following, from USFWS (2007), lists the known physical and biological features that are essential to the conservation of the Comal Springs riffle beetle:

1. High-quality water with no or minimal levels of pollutants, such as soaps and detergents and other compounds containing surfactants, heavy metals, pesticides, fertilizer nutrients, petroleum hydrocarbons, pharmaceuticals and veterinary medicines, and semi-volatile compounds, such as industrial cleaning agents, In particular, respiration in the riffle beetle may be inhibited by pollutants such as soaps and detergents that can affect its respiratory mechanism (Brown, 1987).

2. Aquifer water temperatures that range from approximately 68 to 75 [deg]F (20 to 24 [deg]C).

3. A hydrologic regime that allows for adequate spring flows that provide levels of dissolved oxygen in the approximate range of 4.0 to 10.0 mg/L for respiration of the Comal Springs riffle beetle.

4. Food supply that includes detritus (decomposed materials), leaf litter, living plant material, algae, fungi, bacteria and other microorganisms, and decaying roots.

5. Bottom substrate in surface water habitat of the Comal Springs riffle beetle that is free of sand and silt, and is composed of gravel and cobble ranging in size between 0.3 to 5.0 inches (in) (8-128 millimeters (mm)).

Distribution
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Global Range: (<100 square km (less than about 40 square miles)) Known from Comal Springs spring runs 1, 2, and 3 in Comal County, Texas (entire length of spring is 4 km); and from a single specimen in San Marcos Springs, Hays County, Texas (Bosse et al., 1988; USFWS, 1994).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States TX

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
TX Comal (48091), Hays (48209)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
12 Middle Guadalupe (12100202)+, San Marcos (12100203)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A small aquatic beetle.
General Description: See Bosse et al. (1988) for complete description.
Diagnostic Characteristics: Body contours of Heterelmis comalensis are similar to those of Heterelmis stephani, but H. stephani is appreciably larger and lacks distinct sculpturing on the disk of the pronotum. The parameters of the male genitalia have an inner fringe of hair as in Heterelmis glabra and Heterelmis obscura; such a fringe is absent in Heterelmis longula, Heterelmis obesa, Heterelmis stephani, and Heterelmis vulnerata. Male genitalia appear to be indistinguishable from those of H. glabra, but specimens of H. comalensis are smaller, paler, and more slender than those of H. glabra. It seems probable that this species evolved from an isolated population of H. glabra (Bosse et al., 1988).
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: Almost certainly not a flier based on size of hind wings which are short and non-functional (Bosse et al., 1988).
Riverine Habitat(s): Riffle, SPRING/SPRING BROOK
Habitat Comments: Inhabits the gravel substrates and shallow riffles in spring runs (USFWS, 1994). Found in headwater springs on hard-packed gravel substrate (Bosse et al., 1988). Bowles et al. (2003) speculated that the riffle beetle may be able to retreat back into spring openings or burrow down to wet areas below the surface of the streambed.
Adult Phenology: Diurnal
Phenology Comments: Information not known.
Length: .21 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Biological Research Needs: Life history information sorely lacking.
Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 19May2009
NatureServe Conservation Status Factors Author: Cordeiro, J. (2003); Capuano, N. (2009)
Element Ecology & Life History Edition Date: 03Apr2003
Element Ecology & Life History Author(s): Cordeiro, J.l

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Arsuffi, T. L. 1993. Status of the Comal Springs Riffle Beetle (Heterelmis comalensis Bosse, Tuff and Brown), Peck's Cave Amphipod (Stygobromus pecki Holsinger) and the Comal Springs Dryopid Beetle (Stygopamus comalensis Barr and Spangler). Report submitted to U.S. Fish and Wildlife Service, 611 E. Sixth Street, Grant Bldg., Suite 407, Austin, Texas 78701. Contract No. 14-16-0002-90-207. 26 pp + 5 appendices.

  • Bosse, L. S., D. W. Tuff, and H. P. Brown. 1988. A new genus an species of Heterelmis from Texas (Coleoptera:Elmidae). Southwestern Naturalist. 33:199-203.

  • Bowles, D. E., C. B. Barr, and R. Stanford. 2003. Habitat and pheneology of the endangered riffle beetle Heterelmis comalensis and a coexisting species, Microcylloepus pusillus, (Coleoptera: Elmidae) at Comal Springs, Texas, USA. Archiv für Hydrobiologie 156:361-383.

  • Brown, H. P. 1987. Biology of Riffle Beetles. Annual Review of Entomology 32:253-73.

  • Eckhardt, G. 1995-2009. The Edwards Aquifer Website. Online. Available: http://www.edwardsaquifer.net/index.html.

  • Gibson, J. R., S. J. Harden, an J. N. Fries. 2008. Survey and distribution of invertebrates from selected springs of the Edwards Aquifer in Comal and Hays Counties, Texas. The Southwestern Naturalist 53(1):74-84.

  • McKinney, D. C., and D. W. Watkins, Jr. 1993. Management of the Edwards aquifer: A critical assessment. Technical Report CRWR 244. Center for Research in Water Resources, Bureau of Engineering Research. University of Texas at Austin. 94 pp.

  • Poole, R. W., and P. Gentili (eds.). 1996. Nomina Insecta Nearctica: a checklist of the insects of North America. Volume 1 (Coleoptera, Strepsiptera). Entomological Information Services, Rockville, MD. Available online: http://www.nearctica.com/nomina/nomina.htm

  • U.S. Fish and Wildlife Service (USFWS). 1994. Category and Listing Priority Form.

  • U.S. Fish and Wildlife Service (USFWS). 1995. Proposal to list three aquatic invertebrates in Comal and Hays Counties, Texas, as endangered. Federal Register 60(107):29537-43

  • U.S. Fish and Wildlife Service (USFWS). 2007. Endangered and threatened wildlife and plants; designation of critical habitat for the Peck's Cave Amphipod, Comal Springs Dryopid Beetle, and Comal Springs Riffle Beetle; final rule. Federal Register 72(136):39248-39283.

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