The Status of Plethodon ainsworthi Lazell: Extinct, Extant, or Nonexistent?
Plethodon ainsworthi Lazell was described as a new species in the slimy salamander (Plethodon glutinosus [Northern Slimy Salamander]) complex from two specimens collected in Jasper County, MS, in 1964. Prior to their designation as the type and paratype of the newly described species in 1998, both specimens were presumably stored in strong formalin for 26 years and thus were in poor condition. Plethodon ainsworthi is distinguished from the sympatric Plethodon mississippi (Mississippi Slimy Salamander) by a more attenuated body, as evidenced by a higher snout-vent length (SVL)/head width (HW) ratio, and shorter limbs. Despite numerous searches between 1991 and 1997, no subsequent specimens of P. ainsworthi were found. As a result, P ainsworthi is the only modern-day amphibian in the United States to be declared extinct by the IUCN. In 2000 and 2001, we searched the presumed location of the type specimens of P. ainsworthi for additional specimens. Although we located slimy salamanders, we did not find any specimens with noticeably attenuated bodies or short limbs. We then compared SVL/HW ratios between the two specimens of P ainsworthi, 24 specimens of slimy salamanders that we collected in Jasper County from or near the collection site of P. ainsworthi, and 50 museum specimens of P. mississippi collected from six counties in Mississippi outside of Jasper County. The upper limit of the SVL/HW ratio for some of the specimens we collected, as well as for some of the museum specimens of P mississippi, was considerably higher than the 7.2 reported for P mississippi by Lazell (1998). In addition, we found overlap in SVL/HW ratios between P. ainsworthi and one specimen of P mississippi, although this individual did not have short limbs. The distinct morphology of P ainsworthi may be the consequence of the long-tenn, improper preservation of specimens of P mississippi. Our results provide compelling evidence that P. ainsworthi is not a valid taxon.