Glyptemys muhlenbergii

Molecular data and morphological evidence indicate that the genus Clemmys (sensu McDowell 1964) is paraphyletic (see Bickham et al. 1996, Holman and Fritz 2001, Feldman and Parham 2002). Based on morphological data, Holman and Fritz (2001) split Clemmys as follows: Clemmys guttata was retained as the only member of the genus; Clemmys insculpta and C. muhlenbergii were placed in the genus Glyptemys (as first reviser, Holman and Fritz gave Glyptemys Agassiz, 1857, precedence over the simultaneously published genus Calemys Agassiz, 1857); and Clemmys marmorata was transferred to the monotypic genus Actinemys.

Genetic data support the basic features of this arrangement. An analysis of emydid relationships based on molecular data (Feldman and Parham 2002) identified four well-supported clades: Terrapene; Clemmys guttata; C. insculpta and C. muhlenbergii; and Clemmys marmorata, Emys orbicularis, and Emydoidea blandingii. Feldman and Parham retained Clemmys guttata as the only member of that genus; regarded Clemmys marmorata, Emys orbicularis, and Emydoidea blandingii as congeneric (in the genus Emys, which has priority); and placed C. insculpta and C. muhlenbergii in the genus Calemys. However, Feldman and Parham were unaware that Holman and Fritz (2001) had given Glyptemys precedence over Calemys, so the correct generic name for these turtles under the arrangement of Feldman and Parham is Glyptemys. In contrast to Holman and Fritz (2001), Feldman and Parham (2002) argued that placing Clemmys marmorata in the monotypic genus Actinemys would unnecessarily obscure its phylogenetic relationships, and they recommended that marmorata be included in the genus Emys.

See also McDowell (1964), Merkle (1975), Lovich et al. (1991), and Bickham et al. (1996) for information on relationships among turtles of the genus Clemmys (sensu lato).

This species has a discontinuous range with fragmented occurrences, is uncommon, and adversely affected by continual habitat destruction/overcollection.

Since the discontinuity of the range is well established, the range extent was split into three distinct clusters, and then summed; 1) those from Georgia to southern Virginia, 2) those from Maryland to Massachusetts, 3) and those from the Prairie Peninsula/Lake Plain of New York State. Population segments considered extirpated (northwestern Pennsylvania and Lake George, NY) were excluded. Ernst and Lovich (2009) and USFWS (2001) published distribution maps. Range extent was calculated at 97,484.563 sq km.

As of review in 2018, 1,282 element occurrences are known. Although many of these occurrences would have historically been clustered into functioning metapopulations, because of land use changes (fragmentation due to development), many of these functional metapopulations have been separated into distinct colonies by barriers to natural movement (Gibbs et al. 2007, USFWS 2001).

Throughout the bog turtles range, residential and commercial development pressure continues to alter and destroy habitat, and fragment populations. Despite environmental review protection measures, those efforts tend to focus on small scale impacts and not the overall impacts to populations.

Although prescribed grazing can be beneficial to habitat maintenance, USFWS (2001) noted that intensive grazing represented a threat to bog turtles.

Bog turtles are occasionally killed on roads, and road mortality may be significant where bog turtle subpopulations are found along roads (Arndt 1977, USFWS 2001).

Some bog turtle occurrences can be found in powerline and pipeline rights of ways (ROWs). While short-term ROW maintenance can negatively impact turtle subpopulations if conducted without considering the impacts to turtles, in the long-term this ROW management may help maintain the open canopy habitat component that bog turtles need.

Unfortunately, bog turtles are still targeted in the black market pet trade (USFWS 2001). It's suspected that poaching currently occurs at a small proportion of bog turtle sites, but this collection pressure may cause such severe declines that subpopulations are entirely eliminated or driven so low that they become functionally extinct (Ernst and Lovich 2009).

USFWS (2001) noted that fire suppression at a population in Massachusetts has greatly reduced the available bog turtle habitat.

Draining, filling, and inundating bog turtle habitat is noted as one of the primary threats to bog turtles (Ernst and Lovich 2009, USFWS 2001).

Numerous invasive plant species threaten bog turtle habitat (USFWS 2001). Disease has not traditionally be thought of as a huge risk to bog turtles, but a number of states reported numerous states reported finding multiple dead bog turtles as monitored sites in 2010-2011. However, investigations as to the cause were not conclusive.

Natural succession is a perpetual problem at the majority of bog turtle sites (USFWS 2001). Native predators, especially raccoons, take a huge toll on bog turtle nests, juveniles and adults (Ernst and Lovich 2009, USFWS 2001).

A review of the bog turtle through the Climate Change Vulnerability Index by the Pennsylvania Natural Heritage Program found that the turtle indexed as "highly vulnerable" to climate change (PNHP 2011). Marsh habitats could have lasting altered hydroperiods due to climate change, and may become unsuitable for bog turtles.