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Cicindela nigrior Schaupp, 1884

Autumn Tiger Beetle

Federal Protection: No US federal protection

State Protection: No Georgia state protection

Global Rank: G2G3

State Rank: S2

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 26

Habitat Summary for element in Georgia: Gopher Tortoise burrows; sandhills


Description

This medium-sized tiger beetle (11-14 mm [0.43-0.55] inches]in total length) may be metallic green or dull black in color (the green and black color forms are morphologically identical; populations of this beetle may be comprised of all green, all black, or a mix of green and black individuals). There are no elytral maculations.

Similar Species

Adult Cicindela nigrior may be distinguished from C. scutellaris unicolor, which is always green in coloration, by the following characteristics: a) many Georgia specimens of C. scutellaris unicolor have reduced apical lunules (ca. 40% of Georgia specimens have some amount of white at the apical lunules); b) male C. nigrior possess a black labrum with two cleanly separated white spots while male C. s. unicolor have an all-white labrum; c) in C. nigrior, the median tooth of labrum is smaller than the lateral teeth; in C. s. unicolor, the median tooth of labrum is larger than the lateral teeth.

Habitat

Xeric longleaf pine – turkey oak sandhills. Populations of this beetle are known from intact sandhill ecosystems (fire-managed sites with longleaf pine and native flora including wiregrass, Aristida stricta) as well as sites (proximal to intact sandhills) that have experienced anthropogenic disturbances (primitive/unmaintained sand roads and their margins, powerline cuts, firebreaks, sandpits, food plots). Known sites include aeolian dune sandhills on the northeastern sides of blackwater rivers in the Atlantic Coastal Plain (soil types: Kershaw, Lakeland) and xeric sandhills in the Fall Line region. Cicindela nigrior, although often found close to C. scutellaris unicolor, seems to be limited to site where the sand is well-packed and slightly compact (not loose and “sugary” as preferred by C. s. unicolor) and the ground surface is sparsely vegetated with grasses. Such habitat conditions are often associated with slight slopes.

Diet

Adults and larvae are predaceous and armed with impressively large mandibles. Their prey includes a wide diversity of small arthropods.

Life History

Cicindela nigrior is unique among North American cicindelids in having only a “autumn” (actually late summer–fall–early winter) activity period. (Note: Cicindela scutellaris unicolor is active during both spring and fall, but mating only occurs in the spring, so any coupled pair of green tiger beetles observed in the fall is likely to be C. nigrior). Adults emerge during late August or early September, with peak numbers present from mid-September to late November. In warm years, adults have been found surface-active as late as early January. Xeric sandhill habitats in the Coastal Plain of southern Georgia support five tiger beetle species (C. nigrior, C. scutellaris unicolor, C. tranquebarica, Cicindelidia abdominalis, Ellipsoptera hirtilabris) that are found only in xeric, sandy environments. Larval C. nigrior construct vertical burrows in the sand, and, when inactive, may plug the mouth of their burrow with their head/pronotum.

Survey Recommendations

We recommend continued inventories, range-wide, in an effort to document new C. nigrior populations, as well as periodic monitoring of known C. nigrior sites located on protected lands. The species has yet to be recorded from sandhills along the Alapaha River and the Withlacoochee River in south-central Georgia (both regions have extensive potential habitat). Two notable public lands located in the Fall Line Sandhills region of Georgia (Fort Benning and Fort Gordon), and a well-managed site located in the Atlantic Coastal Plain (Fort Stewart) also possess suitable habitat for C. nigrior, although as of yet beetle populations have not been documented from any of these properties. Additionally, surveys addressing the current status of C. nigrior in southwestern Georgia are needed.

Range

This beetle ranges in the Coastal Plain from southeastern North Carolina to southeastern Mississippi, including portions of the Florida panhandle. In Georgia, populations are known from both the Atlantic and Gulf Coastal Plain regions and from the Fall Line Sandhills. The autumn tiger beetle is rare and locally distributed.

Threats

Loss, degradation and fragmentation of naturally-functioning longleaf pine sandhills threaten the future of this species. Some C. nigrior sites known for Georgia seem to be highly localized, relatively small populations that are potentially vulnerable to overcollection.

Georgia Conservation Status

Since 2010, C. nigrior has been documented from 18 sites in 14 Georgia counties, making Georgia a significant stronghold for this beetle. However, only five of these populations are located on protected lands. The ability of C. nigrior populations to persevere in disturbed habitats, especially along unimproved sand roads, may bode well for the long-term conservation of this species. Surveys addressing the current status of C. nigrior in southwestern Georgia are needed.

Conservation Management Recommendations

Longleaf pine sandhill habitats supporting populations of this beetle should be actively managed using prescribed burns. Careful evaluation of herbicides used in sandhills inhabited by this species is recommended. Inasmuch as these beetles often utilize and dig burrows in primitive sand roads and similar “two-tracks”, paving or profound disturbance to such areas should be avoided when possible.

References

Beaton, G. 2008. Notes on tiger beetle distribution in the state of Georgia, U.S.A., with new county records. Cicindela 40(3): 37–45.

Choate, P.M., Jr. 2003. A field guide and identification manual for Florida and eastern U.S. tiger beetles. University Press of Florida, Gainesville.

Folkerts, G.W., M.A. Deyrup, and D.C. Sisson. 1993. Arthropods associated with xeric longleaf pine habitats in the southeastern United States: A brief overview. Pp. 159–192 In Proceedings 18th Tall Timbers Fire Ecology Conference, The Longleaf Pine Ecosystem: Ecology, Restoration and Management. Tall Timbers Research Inc., Tallahassee, Florida. 418 pp.

Ivester, A.H., and D.S. Leigh. 2003. Riverine dunes on the coastal plain of Georgia, USA. Geomorphology 51: 289–311.

Knisley, C.B. 2011. Anthropogenic disturbances and rare tiger beetle habitats: benefits, risks, and implications for conservation. Terrestrial Arthropod Review 4: 41–61.

Pearson, D.L., C.J. Kazilek, C.B. Knisley, and D.P. Duran. 2015. A field guide to the tiger beetles of the United States and Canada: Identification, Natural History, and Distribution of the Cicindelinae, Second Edition. Oxford University Press. 328 pp.

Stevenson, D.J., G. Beaton, and M. J. Elliott. 2013. The phenology, distribution, habitat, and status of the tiger beetles Cicindela nigrior Schaupp and Cicindela scutellaris unicolor Dejean (Coleoptera: Cicindelidae) in the Coastal Plain of Georgia. Cicindela 45(2-3): 49–68.

Stevenson, D.J., J.D. Mays, and G. Beaton. 2019. Notes on unusual violet-blue coloration in the autumn tiger beetle, Cicindela nigrior Schaupp. Cicindela (In review)

Vick, K.W. and S.J. Roman. 1985. Elevation of Cicindela nigrior to species rank. Insecta Mundi 1(1): 27–28.

Authors of Account

Dirk J. Stevenson

Date Compiled or Updated

1 December 2018

Photo by Jonathan Mays. Image may be subject to copyright.