Morphological and molecular characterization of a new species of leech (Glossiphoniidae, Hirudinida): Implications for the health of its imperiled amphibian host (Cryptobranchus alleganiensis)

Abstract

The hellbender (Cryptobranchus alleganiensis) is among the most intriguing and imperiled amphibians in North America. Since the 1970s and 80s, western populations of the Ozark and eastern subspecies in Missouri have declined by nearly 80%. As a result of population declines, the Ozark hellbender was recently federally protected as an endangered species, and the eastern subspecies was granted protection under CITES. Although habitat degradation is probably the biggest threat to hellbender populations, recent evidence suggests that pathogens including chytrid fungus and “flesh-eating” bacteria may also contribute to declines in Ozark hellbenders. Leeches, which are very common on Ozark hellbenders, have recently been implicated as possible vectors of disease among Ozark hellbenders but have not been described in eastern hellbenders or outside of Missouri and Arkansas. We discovered a population of leeches on eastern hellbenders in southwest Virginia and confirmed that the species of leech is within the genus Placobdella, but is morphologically and genetically distinct from all previously described leech species. We named the new species Placobdella appalachiensis sp. n. Moser and Hopkins, based on the mountainous region in which it was discovered. Our surveys over a three consecutive year period suggested that this leech species may be patchily distributed and/or have a narrow geographic range. We consistently detected leeches at one site (mean prevalence in 80 hellbenders = 27.5%; median intensity = 3.0 leeches per parasitized hellbender [range 1 – >250 leeches]) during three years of surveys, but we never found leeches in any of our other seven study sites in two streams (mean prevalence in 139 hellbenders = 0%). We found a significant positive relationship between hellbender body size and the intensity of parasitism, and we suggest the possibility that the behavioral ecology of adults leading up to reproduction may increase their encounter rates with parasites. We discuss the potential conservation implications of discovery of leeches in this stream, and make recommendations for future mitigation and monitoring efforts.

Evidence of ectoparasite-induced endocrine disruption in an imperiled giant salamander, the eastern hellbender (Cryptobranchus alleganiensis)

“…Previous studies have documented leeches on Ozark hellbenders (Dundee and Dundee, 1965;Nickerson and Mays, 1973;Moser et al, 2008;Huang et al, 2010;Bodinof et al, 2012); however, only recently have leeches been detected in populations of the eastern hellbender (Hopkins and DuRant, 2011;Davis and Hopkins, 2013;Hopkins et al, 2014). Genetic analyses revealed that this leech is a new species in the genus Placobdella, and is distinct from the species of leech that parasitizes Ozark hellbenders (Hopkins et al, 2014). Leech infection frequency (48%) and mean (±s.d.)…”

“…We selected this stream because it drains a predominantly forested watershed and still harbors a relatively large population of hellbenders, with individuals successfully reproducing. The area we chose to sample was located just upstream of the stream reach where we previously documented the presence of leeches and trypanosomes (Hopkins et al, 2014;Hopkins and DuRant, 2011;Davis and Hopkins, 2013).…”

“…), were detected in a population of giant salamanders (eastern hellbenders, Cryptobranchus alleganiensis Daudin) in Southwest Virginia (Hopkins et al, 2014;Hopkins and DuRant, 2011;Davis and Hopkins, 2013). It is possible that leeches serve as the vector for trypanosome transmission to hellbenders (Hamilton et al, 2007, and citations therein).…”

Current land use is a poor predictor of hellbender occurrence: why assumptions matter when predicting distributions of data‐deficient species

“…1). Together, these drainages mark the eastern extent of the hellbender's range in Virginia and a largely unstudied portion of the species' total range (but see Hopkins et al, , 2014Hopkins et al, , 2016DuRant et al, 2015). Both drainages overlap portions of the Blue Ridge and Ridge and Valley physiographic provinces of the greater Appalachian Highlands (Fenneman, 1928;Fig.…”

Haematological and immunological characteristics of eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) infected and co-infected with endo- and ectoparasites

“…Hellbenders are known to harbour several parasites and pathogens ( Briggler et al ., 2007a , b , 2008 ; Huang et al ., 2010 ; Bodinof et al ., 2011 , 2012 ; Burgmeier et al ., 2011 ; Gonynor et al ., 2011 ; Regester et al ., 2012 ; Souza et al ., 2012 ; Tominaga et al ., 2013 ), but the effects of these organisms on hellbender health and survival remain largely unknown. Recently, we discovered and described a new species of ectoparasitic leech ( Placobdella appalachiensis ) in eastern hellbenders in southwest Virginia ( Hopkins et al ., 2014 ). In the stream reach where this leech is currently known to occur in abundance, its prevalence of infection during late summer ranges from 21 to 48% ( Hopkins et al ., 2014 ; DuRant et al ., 2015 ).…”