Introduction

Data acquisition for this project, which began in 1998, is ongoing. The aim was to produce a companion document to Atlas of Amphibians in Tennessee (Redmond and Scott 1996), which is available in hard copy from the Center of Excellence for Field Biology, Austin Peay State University, Clarksville, Tennessee, and online at http://www.apsubiology.org/tnamphibiansatlas/.  The Internet version of Atlas of Amphibians in Tennessee has the added feature of links to photographs of species and updates on nomenclature, taxonomy, and new distribution records that have appeared subsequent to publication of the original document.

The online version of Atlas of Reptiles in Tennessee (http://www.apsubiology.org/tnreptileatlas/) was launched in 1 May 2008 with introductory and background information, plus species accounts and distribution maps for species in the family Viperidae. Additional species accounts were added periodically until August 2008 when accounts for all species known to occur in the state were completed. Members of the Viperidae (Crotalidae in some classifications) were chosen as the first group to present because their venomous nature is of interest to biologists and laymen alike. The Introduction and first species account (Crotalus horridus) were posted 1 May 2008. The last species account (Chrysemys picta complex) was uploaded 15 May 2012. Updates that add newly acquired distribution and taxonomic data are taking place four times each year soon after publication of each quarterly issue of Herpetological Review.

This project was guided by the following specific objectives:

1.      Seek out occurrence records for reptiles in Tennessee from literature sources, museum collections, and through additional field work;

2.      Verify identifications of museum specimens and accompanying locality data;

3.      Verify locality data from all sources;

4.      Where possible, use GPS coordinates to digitize locality data from all sources;

5.     Develop individual species accounts that provide (1) an overview of  state-wide distribution, (2) a detailed distribution map that displays localities currently considered valid for the species in Tennessee, (3) a list of museum specimens examined listed alphabetically by counties, (4) a list of sources of literature records listed chronologically by counties, (5) problematic and/or questionable records, and (6) a brief discussion of conservation status in Tennessee;

6.      Disseminate the results electronically via the Internet;

7.      Develop a hardcopy version of the web site.

We hope the information contained in this website will be used to further the cause of reptile conservation in Tennessee by providing essential baseline information for education and future research on these often-maligned creatures. Many species have glaring gaps depicted in the mapped distributions. Our wish is that this will encourage readers to fill these gaps by documenting and publishing new county records.

With a few exceptions, the scientific and common names used in the individual species accounts are those provided by the authors of the various subsections found in the seventh edition of the official herpetological names list (Crother 2012). Nomenclature above the level of species follows that of Conant and Collins (1998).



Map Development and Presentation

Baseline Distribution Data

Baseline distribution data were taken from two main sources: museum collections and literature sources. Twenty-five institutions scattered throughout eastern United States (Table 1) were visited to obtain occurrence data and verify species identifications. The collection at Austin Peay State University continues to be a source of distribution data. As for information in the literature, the earliest published Tennessee reptile record was Harlan’s 1835 report of Chelonura [=Macrochelys] temminckii “from a tributary stream of the Mississippi above Memphis.” Literature searches not only included reviews of papers and reports from well-known and established peer-reviewed scientific journals, but also “gray” literature sources such as unpublished technical reports, abstracts, and newspaper and popular magazine articles. As data were compiled, they were stored, sorted, and analyzed with Microsoft Excel and Access data base software. When latitude and longitude data were missing from a record and the locality data were sufficient, coordinates were assigned using one or more of the following aids: county road maps; Tennessee Atlas and GazetteerTM;Topozone.com website; Maptech.com Mapserver; Topo USATM software; GEOLocate software (courtesy of Tulane University); Yahoo.com maps service; and Google.com maps service. Distribution maps were generated with ArcGIS 9.2 software. 

As of January 2017, our literature search has yielded 4,238 Tennessee reptile occurrence records in 668 documents. Surveys of institutional collections has turned up 10,768 records, represented by 11,688 voucher specimens and photographs dating back to 1855. The top five most-productive collections, and numbers of records (in parentheses) obtained from each, include those at Memphis State University (2,500), Austin Peay State University (1,919), Carnegie Museum (1,377), University of Florida (865), and US National Museum (686). All together, these contributed 7,345 records or 68% of the grand total from all 25 collections surveyed.

Reports representing 68 species of extant reptiles in Tennessee were obtained from literature sources; 59 species were represented among the museum specimens examined. Of the 68 species reported in the literature, 60 are considered native to Tennessee and represent one family of crocodilians, four families of turtles, five families of lizards, and five families of snakes. The other eight, discussed in a separate section (Erroneous Species Reports), are likely based on encounters with escaped (or released) exotics, misidentified specimens, or corrupted locality data.

Key and Explanation of Map Symbols

Symbols used on the distribution maps are explained in the following key:

Key to Map Symbols
 
     Exact locality, based on specimen(s) or photographs examined
     Exact locality, based on literature record believed valid
     Approximate locality based on specimen(s) or photographs examined
     Approximate locality based on literature record believed valid
     County record only, based on specimens or photographs examined
     County record only, based on literature report believed valid
     Type locality
?      Questionable and/or problematic record

An exact locality (solid circle or solid square) is one based on data of sufficient detail and accuracy that the actual collection site falls within the bounds of the symbol provided on the distribution map. An approximate locality (open circle or open square) is one based on data lacking detailed information needed to pin point the site on a topographic map and therefore the actual collection site may not fall within the bounds of the map symbol. Based on available locality data, map symbols denoting approximate localities were placed near a topographic feature, such as the nearest town, park, game preserve, nature preserve, recreation area, or well-known camp. County records only (solid or open triangle) are those without locality data other than the county of origin. Type localities are denoted by an asterisk. A type locality is the place where the population from which a type specimen was taken occurs” (Mayer and Ashlock 1991), which may be exact or approximate. Localities marked by a question mark are considered questionable or problematic because the data are likely erroneous and/or there is reason to suspect a misidentification. Records of this nature are discussed in the appropriate species account. A map of Tennessee showing county names and boundaries is provided in Figure 1.

Plotting Rules and Protocols

A typical locality record from both museum and literature sources is based on a specimen or specimens collected on a single date from a single specific geographic locality. Plotting all records for a species could result in cluttered and confusing distribution maps. Thus, certain criteria and standard procedures were developed and used to not only determine which records would be plotted, but how records would be plotted. The primary goal of these protocols was to condense large and sometimes overlapping species data sets, yet still provide adequate detail to allow the recognition of distribution patterns and identification of counties and other geographic areas where a species is currently not known to occur.

To avoid perpetuating possible errors in the literature regarding the distribution of a particular species, we did not plot locality records from a literature source where the author(s) used second-hand sightings as the basis for the record. Many of these “hearsay” accounts are discussed in the appropriate species account.

In order to avoid cluttered distribution maps, we developed and used a computer protocol that allowed only one symbol to be plotted for a specific geographic locality (either exact or approximate). This avoided the confusion of many symbols being plotted one on top of another. Also, we decided that locality records based on a specimen(s) from a museum source took precedence over records for the same locality from a literature source.

For a given species, county records only (solid and open triangles) were only plotted when no other exact or approximate locality data (either museum or literature) were available for that county. Below are three examples that illustrate the use of these protocols.

Example 1 – There are specimens of Trachemys scripta in several museum collections with different collection dates, but with a common collection site of Reelfoot Lake, Samburg. This site for T. scripta is also mentioned several times in the literature. In order to avoid clutter on the distribution map for T. scripta, only one symbol, a solid circle, appears on the distribution map.

Example 2 – A locality record for Sistrurus miliarius from the literature source Jacob (1981) was based on a specimen originally in the Memphis State University herpetology collection and now in the collection at Austin Peay State University. This locality is denoted on the distribution map for S. miliarius as a single map symbol, a solid circle.

Example 3 – Clark et. al (2003) provided what we believe to be valid information that Crotalus horridus was found in Williamson County. Because the authors provided no specific or approximate locality data, this record was classified as a county record only (open triangle). However, the record was not plotted on the final distribution map for C. horridus because other data were available for Williamson County. These data included an exact locality based on a specimen examined (solid circle), an approximate locality based on a specimen examined (open circle), and an approximate locality based on a literature record believed valid (open square).

Updates

Subsequent to the initial posting of species accounts and distribution maps, we will continue to search the literature for new state and county records.  These new data will be used to periodically update the website.

If new records for a species are based on recently acquired voucher specimens or photographs in Austin Peay State University’s Museum of Zoology, they will be 1) plotted on the species' distribution map with an appropriate map symbol, 2) identified by their APSU catalog number in the account’s Specimens Examined by Counties section, and 3) cited in the account’s Literature Sources by Counties section. Also, the bibliographic information identifying the source of new records will be added to the website’s Literature Cited section.

If new records for a species are based on voucher specimens or photographs in collections other than APSU’s, no catalog number will be noted in the Specimens Examined by Counties section. However, these new records will be added to the species' distribution map with an appropriate map symbol and cited in the account’s Literature Sources by Counties section. The reference will be added to the website’s Literature Cited section.

Along with the changes mentioned above, each updated account will end with a statement following the original posting date that identifies the date of the latest revision.


Erroneous Species Reports

An Ornate Box Turtle (Terrapene ornata) from just east of Memphis was mentioned by Parker (1948) who suspected it might have been released in the area by a traveler. The “Keeled Musk Turtle” (Sternotherus carinatus) was included in Brimley’s (1926) “Revised key and list of the amphibians and reptiles of North Carolina” as a species not yet known from North Carolina but occurring in neighboring Tennessee. However, no references or authorities were cited as the source for this information and no reports are known for the species in Tennessee.

The Texas Horned Lizard (Phrynosoma cornutum) was included by Gentry (1956) on his state reptile list, but was also clearly identified as non-native species that sometimes ends up in the wild as released or escaped pets. One specimen of P. cornutum from Graysville (Rhea County) in the University of Illinois Museum of Natural History collection (UIMNH 33960) also probably represents a release.

A single specimen of the Eastern Diamond-backed Rattlesnake (Crotalus adamanteus) from near Bolivar was among the reptiles listed from Hardeman County by Norton and Harvey (1975), but it was considered to have been brought to the area from its native range. In 2007, another specimen of this rattlesnake was found in Grundy County and housed for a time at the Knoxville Zoo (Niemiller et al. 2013). It too was considered an introduction from outside Tennessee. The Gopher Snake (Pituophis catenifer) was reported by Gentry (1956) based on specimens from “the Tennessee River area” that in some cases were intermediate between P. melanoleucus and P. catenifer. However, since no subsequent reports or voucher specimens exists to corroborate these assertions, P. catenifer is not considered part of the state’s reptile fauna. Known at the time as Liopeltis vernalis, the Smooth Greensnake (Opheodrys vernalis) was reported by Endsley (1954) as “not abundant” but yet “not uncommon” in western Tennessee. More specifically, he references “a preserved specimen collected near Henderson, Tennessee, May 15, 1934.” However, the specimen could not be located and the occurrence of this species in the state is considered doubtful. Lastly, among the records considered questionable is the Lined Snake (Tropidoclonion lineatum). Represented by a specimen in the US National Museum (USNM 56030) with “Sherwood, Franklin County, Tennessee” as the collection locality, this record may likely be the result of corrupted locality data because the closest records to the Franklin County locality are approximately 530 km away in Jefferson County, Missouri (Johnson 1987). Ramsey (1953, p. 7) also had doubts about the validity of this record as expressed in the following quote:

The locality given for U. S. Nat. Mus. No. 56030 as Sherwood, Franklin County, Tennessee is . . . regarded with doubt. It is remote from any other records for the species. Dr. Doris M. Cochran has informed me that this specimen, along with some 5000 other specimens, was given to the United States National Museum by the estate of Julius Hurter, but that Hurter’s original catalogues and correspondence were never made available to the museum. There is thus no way by which to check upon the source of this specimen.

Other non-native species that have turned up in Tennessee include the Spectacled Caiman (Caiman crocodilus), Gopher Tortoise (Gopherus polyphemus), Green Iguana (Iguana iguana), Brown Anole (Anolis sagrei), Indo-Pacific Gecko (Hemidactylus garnotii), and Mediterranean Gecko (Hemidactylus turcicus) (Niemiller et al. 2013). Of these, only the Mediterranean Gecko has been documented in all three grand divisions of the state in small colonies containing both adults and juveniles, which suggests at least temporary establishment (Nordberg et al. 2013).


Species of Possible Occurrence

Three species (one turtle and two snakes) occur close enough to the state’s boundary to be considered as possible residents. The Alabama Map Turtle (Graptemys pulchra) is know from five localities along the Conasauga River drainage in Whitfield and Murray counties, Georgia (John Jensen, personal communication). The northernmost of these sites is within 14 river kilometers of the portion of the Conasauga that flows through Bradley County, Tennessee. The Chicken Turtle (Deirochelys reticularia) has been recorded in New Madrid County, Missouri (Daniel et al. 2014) and Mississippi County, Arkansas (Niemiller et al. 2013), both just across the Mississippi River from Tennessee. Records of Graham’s Crayfish Snake (Regina grahamii) also exist from Mississippi County, Arkansas (Trauth et al. 2004) and from Dunklin (Daniel et al. 2014, verified) and New Madrid (Johnson 2000, unverified) counties Missouri, also a short distance across the Mississippi River from Tennessee.


Numbers of Species Per County

As of January 2015, the numbers of species known from each county based on both museum specimens and literature reports ranged from a low of four in Loudon County to a high of 46 in Shelby County (Fig. 2). One noticeable geographical trend among the total data set is that counties with the highest reptilian species diversity are 1) counties with colleges or universities that have a history of research and instruction in herpetology and/or 2) counties that possess or are close to accessible tracts of public lands. Of the eight counties with the highest number of documented species, all fall into one or both of these categories. Shelby County (46 species) has the University of Memphis (formally Memphis State University), T. O. Fuller State Park, and Meeman-Shelby Forest State Park. Hardeman County (45 species) is just one county removed from Shelby and is well represented by reptile records in the literature and among specimens in the former Memphis State University herpetology collection (now housed at Austin Peay State University). Stewart County (44 species) includes Stewart State Forest, Cross Creeks National Wildlife Refuge, and the southern half of Land Between The Lakes, plus it is within easy driving distance to Austin Peay State University and Murray State University. Obion County (40 species) includes portions of Reelfoot National Wildlife Refuge, Reelfoot Lake State Park, Reelfoot State Wildlife Management Area, and is near the University of Tennessee at Martin. Montgomery County (39 species) has Austin Peay State University, Dunbar Cave State Park and Natural Area, Shelton Ferry Wetland, Haynes Bottom Wildlife Management Area, and near-by Land Between The Lakes. Blount County (39 species) is within easy reach of the University of Tennessee at Knoxville, and include portions of Great Smoky Mountains National Park and Cherokee National Forest. And finally, Franklin and Hamilton counties combined (with 38 species each) include The University of the South and The University of Tennessee at Chattanooga, plus parts of Franklin-Marion State Forest and Arnold Air Force Base, Harrison Bay State Park, and the area formerly occupied by the Volunteer Army Ammunition Plant.

Posted: 1 May 2008

Latest Update: 27 January 2017

Atlas of Reptiles in Tennessee - Title/Contents Page  


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