Cryptobranchus alleganiensis

From Frost's Amphibian Species of the World (accessed May 2021): Sabatino and Routman (2009) suggested on the basis of mtDNA analysis that nominal bishopi is phylogenetically imbedded within alleganiensis and that bishopi forms a paraphyletic grouping, with the North Fork of the White River and the Spring River populations in Missouri, more clearly related to populations of alleganiensis in the northern Ozarks, Ohio, and Tennessee, than to the bishopi population of the Current and Eleven Point River drainages of Missouri. Crowhurst et al. (2011), reporting on statistical similarity of microstellite DNA across drainages in the Ozarks of Missouri, provided a more nuanced view: with Cryptobranchus bishopi populations sharing morphological characters but being composed of two genetically distinctive lineages associated with a) the North Fork and Bryant Creek drainages, and b) Current River and Eleven Point River drainages, with the North Fork and Bryant Creek populations more similar to alleganiensis. Personal comment (Frost): While the two populations of nominal bishopi (of which the Current River populations carries the name bishopi) share a distinctive morphology it seems clear that both nominal bishopi and alleganiensis are, not surprisingly, are both species complexes. A detailed phylogeographic study is required, not just of drainage in Missouri, but throughout the range, to delimit these species, particularly given the continent-wide endangerment of virtually all populations.

Wide range in the central interior portion of the eastern U.S. Declines seem to be occurring across the range, but much is still unknown and better information is needed on the conservation status of this species in much of its range.

The range extends from southern Illinois, southern Indiana, Ohio, Pennsylvania, and southwestern and southcentral New York to central and southcentral Missouri, northern Arkansas, northern Mississippi, Alabama, northern Georgia, the western Carolinas, western Virginia, West Virginia, and extreme western Maryland. Populations in the White River system in southern Missouri and northern Arkansas often have been recognized as a distinct subspecies (C. a. bishopi; see taxonomy comments).

In Kentucky, near the center of the range, Barbour (1971) regarded the species "most common in the upper reaches of the Cumberland, Kentucky, and Licking river systems." In Tennessee, no records exist for locations west of the Tennessee River (Redmond and Scott 1996). Collections are known from southeastern Kansas (Neosha River), but these were likely introduced and not from a naturally occurring population (Collins 1982, 1993; Busby, pers. comm. 1994). There are early reports, of uncertain validity, of hellbenders in Iowa (Nickerson and Mays 1973). Old records from the Great Lakes (Lake Erie) drainage are probably erroneous (Pfingsten and Downs 1989, Harding 1997).

Data were not available for Ohio, Kentucky, Indiana, Arkansas, or Missouri, however, the MCP encompasses the approximate ranges from Ohio, Kentucky and Indiana. Inclusion of the limited range from Arkansas and Missouri would still seat the range extent well within the assigned category. Range extent calculated using available data: 563,885.104 sq km.

There are many hundreds of occurrences in at least several dozen rivers.

Most maps in state amphibian and reptile books do not distinguish between extant and historical occurrences. Redmond and Scott (1996) mapped more than 50 locations in Tennessee. Green and Pauley (1987) mapped locations in 22 counties in West Virginia. Tobey (1985) mapped 19 observation/collection sites in Virginia. Mount (1975) mapped 8 locations in Alabama. Pfingsten and Down (1989) mapped a couple dozen post-1950 locations in about 15 different rivers in Ohio; most rivers with pre-1950 locations also had post-1950 locations. Phillips et al. (1999) mapped post-1980 locations in two counties in Illinois, with four additional pre-1980 county records. Minton (1972, 2001) stated that in Indiana hellbenders persist in fairly good numbers or as a reproducing population only in Blue River. Johnson (1987, 2000) mapped locations in 18 counties in Missouri. Trauth et al. (2004) mapped 11 localities in 4 general areas in Arkansas.

In the past, collection from for commercial biological supply houses for anatomical dissection had impacts on local hellbender populations (Swanson 1948, Harrison 1951, Mayasich et al. 2003). Phillips and Humphries (2005) cited a number of scientific studies that killed remarkable numbers of hellbenders. Incidental persecution by fishermen likely occurs throughout the range (Mayasich et al. 2003). Although likely restricted, hellbenders do make their way into the legal and black market pet trades (Gibbs et al. 2007, Mayasich et al. 2003).

Water withdrawals to facilitate shale gas development has been noted as a threat to hellbender populations (Lipps 2013, P. Petokas pers. comm.).

Across the hellbender's range, manipulation of waterways through damming, channelization, channel rerouting, and rock removal have had serious impacts on hellbender populations and their abilities to disperse (Humphries 1999, Lipps 2013, Hulse 2010, P. Petokas pers. comm.).

Batrachochytrium dendrobatidis (Bd) has been detected in hellbenders from nearly half of populations sampled in Pennsylvania (Regester et al. 2012) and Georgia (Gonynor et al. 2011), however, mortality and population declines have of hellbenders have not been tied to Bd infection. Ranavirus has also been found in hellbenders, but like Bd, hellbender mortality has not been tied to ranavirus (Lipps 2013). A study focused on Batrachochytrium salamandrivorans did not detect the pathogen in hellbenders (Bales et al. 2015). Evidence exists that introduced brown trout may target young hellbenders (Gall 2008). Hulse (2010) suggested that non-native crayfish may also negatively impact hellbender populations.

It's been suggested that northern pike and muskellunge may prey on hellbenders (Foster et al. 2009). Hulse (2010) suggested that reintroduced river otters to Pennsylvania rivers could have implications to already reduced populations of hellbenders.

The hellbender's range largely overlaps with active coal mining in Pennsylvania, Ohio, West Virginia, Kentucky, Maryland and Virginia. The loss of hellbenders from aquatic systems that have been polluted by acid mine drainage has been well documented (Lipps 2013, Nickerson and Mays 1973). While Lipps (2013) noted that water quality in Ohio has generally improved since the 1970's, he also noted the potential for additive or synergistic effects of pollutants. In the past ten years shale gas drilling has greatly expanded, and impacts from shale gas development to aquatic systems have been documented (PA Department of Environmental Protection data).

Siltation from agriculture, eroding stream banks, water treatment facilities, roads, and construction activities are implicated in reducing, and even eliminating hellbender habitat (Lipps 2013). In addition to impacting the microhabitats used by adult hellbenders, the pebble habitats used by larval hellbenders may be particularly vulnerable to siltation (Lipps 2013).