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The Status of Plethodon ainsworthi Lazell: Extinct, Extant, or Nonexistent?
John G. Himes and David C. Beckett

Southeastern Naturalist, Volume 12, Issue 4 (2013): 851–856

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851 J.G. Himes and D.C. Beckett 22001133 SOUTSoHuEthAeSaTsEteRrnN NNaAtTurUaRliAstLIST 1V2o(4l.) :1825,1 N–8o5. 64 The Status of Plethodon ainsworthi Lazell: Extinct, Extant, or Nonexistent? John G. Himes1 and David C. Beckett2,* Abstract - 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-term, improper preservation of specimens of P. mississippi. Our results provide compelling evidence that P. ainsworthi is not a valid taxon. Introduction In 1998, James Lazell described a new species of salamander, Plethodon ainsworthi (variously called Ainsworth’s Salamander, Bay Springs Salamander, or Catahoula Salamander), from two specimens collected in Jasper County, MS, by Jackson Harold (J.H.) Ainsworth on 12 June 1964 (Lazell 1998). The specimens were in the possession of J. William Cliburn at the University of Southern Mississippi until approximately 1990, at which time they were transferred to the Mississippi Museum of Natural Science (MMNS) and subsequently discovered by Lazell in 1991. Lazell (1998) described the type specimen of P. ainsworthi as “very brittle, apparently from long submersion in strong formalin.” It is very probable from Lazell’s description and my (D.C. Beckett’s) observations of the state of the Cliburn 1Florida Fish and Wildlife Conservation Commission, 3911 Highway 2321, Panama City, FL 32904-1658. 2Department of Biological Sciences, 118 College Drive # 5018, Hattiesburg, MS 39406-0001. *Corresponding author - David.Beckett@usm.edu. J.G. Himes and D.C. Beckett 2013 Southeastern Naturalist Vol. 12, No. 4 852 collection that the specimens were placed in “strong formalin” almost immediately after capture and remained in that condition for 26 years (1964–1990). J.H. Ainsworth was deceased when Lazell discovered the specimens, and the exact location of their collection is unknown. However, a label in the jar containing the salamanders identified the specimens as Plethodon glutinosus (now Plethodon mississippi Highton [see Highton 1989]) and described the collection site as “2 Mi S. of [the town of] Bay Springs … in springhead litter” (Lazell 1998). Kenneth Ainsworth, brother of J.H. Ainsworth, identified a mesic woodland area with springs and seeps on the Ainsworth property two miles south of Bay Springs, where he believed his brother had collected the salamanders. Lazell (1998) searched this property for additional specimens of P. ainsworthi on a minimum of 17 occasions between 1991 and 1997, including several instances in which searches included inspection under hardwood slabs that had been placed at the site as cover objects. None of these searches produced specimens of P. ainsworthi. However, Lazell (1998) reported that “in the drier areas” [at the site] P. mississippi, the only other member of the P. glutinosus complex (sensu Highton1989) that occurs in the area, was “very common”. Lazell (1998) distinguished P. ainsworthi from the sympatric and superficially similar P. mississippi by the former species’ more attenuated body and shorter limbs (snout–vent length /head width ratio = 7.9–8.4 for P. ainsworthi vs. ≤7.2 for P. mississippi). Both specimens of P. ainsworthi were in very poor physical condition due to improper preservation techniques, and the paratype was destroyed by Lazell during an attempt to clear and stain it for vertebral examination. Thus, only the type specimen remains available for examination (Lazell 1998). Clarification of the status of P. ainsworthi therefore required the location of other specimens (either in the field or in a scientific collection) and a subsequent comp arison to specimens of P. mississippi. Our objective was to clarify the status of P. ainsworthi by intensively surveying for salamanders at and near the presumed historic collecting site in southwestern Jasper County. In addition, we made morphological comparisons of 1) specimens of slimy salamanders collected during this study, and 2) specimens of P. mississippi collected in the past from various other localities across Mississippi, to the two specimens designated as P. ainsworthi (Lazell 1998). Methods From December 2000 to November 2001, we conducted seven surveys at the Ainsworth property, the presumed historic collection site (based on the collection label written by J.H. Ainsworth and additional information received from Kenneth Ainsworth) of P. ainsworthi (3 km southeast of Bay Springs, Jasper County), as well as three surveys at the nearest forested site to which we had access, located 8 km to the east (also in Jasper County). We collected all adult, non-egg brooding slimy salamanders (a distinction between P. mississippi and P. ainsworthi was not attempted in the field) encountered under natural cover objects (logs, stumps, leaves, etc.) during the surveys. 853 J.G. Himes and D.C. Beckett 2013 Southeastern Naturalist Vol. 12, No. 4 After preserving the salamanders in 70% ethanol, we calculated their snout–vent length (SVL; measurement made to the posterior angle of the vent)/head width (HW) ratios, as in Lazell (1998). We then compared the ratios for 1) the salamanders we collected and 2) those we calculated for museum specimens (Mississippi Museum of Natural Science [MMNS]) of P. mississippi collected from Forrest, Grenada, Hancock, Lauderdale, Madison, and Tishomingo counties, MS (Fig. 1) to the ratios calculated by Lazell (1998) for the type and paratype of P. ainsworthi. We randomly selected from the museum collections 10 adult salamanders from each county for the SVL/HW comparison, with the exception of Grenada County, where only seven adult specimens were available for examination. Material examined The type specimen of P. ainsworthi is in the collection of the Harvard Museum of Comparative Zoology (MCZ-125869). All the museum specimens of P. mississippi that we examined were from the herpetology collection of MMNS. Information on the location of collection sites within counties was not available. Unless otherwise specified, each catalogue number refers to one individual. Figure 1. Location of counties in Mississippi where slimy salamanders (Plethodon glutinosus complex) were collected and measured. Salamanders from Forrest, Grenada, Hancock, Lauderdale, Madison, and Tishomingo counties had been collected previously by other investigators and deposited in the Mississippi Museum of Natural Science. Salamanders from the presumed historic collecting site of Plethodon ainsworthi and from a site located 8 km to the east (both sites in Jasper County) were collected during this study. J.G. Himes and D.C. Beckett 2013 Southeastern Naturalist Vol. 12, No. 4 854 Forrest County: MMNS 51-17, 51-128, 51-136, 560, 5452, 5453, 5456, 5457, 5459, 5460; total n = 10. Grenada County: MMNS 2555, 2556, 5389, 5390, 5391, 5392, 5393; total n = 7. Hancock County: MMNS: 53-90, 53-91, 53-92, 53- 342, 53-343 (n = 2), 1997, 2049 (n = 2), 2062; total n = 10. Lauderdale County: MMNS 1303, 1436, 1437, 1439, 3183, 3185, 3187, 3188, 3189, 3191; total n = 10. Madison County: MMNS 133, 134, 135, 161, 162, 163, 164, 168, 696, 926; total n = 10. Tishomingo County: MMNS 52-949, 52-950, 56-187 (n = 4), 1415, 2058 (n = 2), 2460; total n = 10. Results We located 29 individuals (27 adults) of slimy salamanders during the seven surveys of the presumed historic collection site of P. ainsworthi. Of these, we calculated SVL/HW ratios for all specimens except the two juveniles (not collected), a female brooding a clutch of eggs (not collected), and six other adult individuals (deposited into the Oklahoma State University herpetology collection before ratios could be calculated). In addition, we located four adult slimy salamanders during surveys of the site located 8 km east of the presumed P. ainsworthi collection site. We calculated SVL/HW ratios for all four of these specimens. The slimy salamanders that we collected from the presumed P. ainsworthi site and the site located 8 km to the east had relatively low mean (± 1 SE) SVL/HW ratios (minimum-maximum, sample size): 6.6 ± 0.11 (5.6–7.4, n = 20) and 6.6 ± 0.17 (6.2–7.0, n = 4), respectively (Table 1). The specimens of P. mississippi that we examined from the MMNS collection had SVL/HW ratios varying from a mean of 6.6 (Forrest County, Hancock County, Lauderdale County) to a mean of 7.3 (Madison County) (Table 1). Discussion After examining the type specimen of P. ainsworthi (which we received on loan from the Museum of Comparative Zoology, Harvard University), we agree that it has a more attenuated body and shorter limbs than do the specimens of Table 1. Snout–vent length (SVL)/head width (HW) ratios of slimy salamanders, ± one standard error (SE). Min. = minimum and max. = maximum. County in Mississippi where collected Mean SVL/HW ratio ± 1 SE (min.–max., sample size) Forrest 6.6 ± 0.10 (6.0–7.2, n = 10) Grenada 6.9 ± 0.10 (6.6–7.1, n = 7) Hancock 6.6 ± 0.08 (6.1–7.0, n = 10) JasperA 6.6 ± 0.11 (5.6–7.4, n = 20) JasperB 6.6 ± 0.17 (6.2–7.0, n = 4) Lauderdale 6.6 ± 0.08 (6.4–7.1, n = 10) Madison 7.3 ± 0.14 (6.5–8.2, n = 10) Tishomingo 6.9 ± 0.12 (6.2–7.6, n = 10) APresumed historic collection site of P. ainsworthi. B8 km east of presumed historic collection site of P. ainsworthi. 855 J.G. Himes and D.C. Beckett 2013 Southeastern Naturalist Vol. 12, No. 4 P. mississippi that we collected from Jasper County. However, three of the 20 and six of the 57 specimens of P. mississippi that we examined from the collection site of P. ainsworthi and from outside Jasper County, respectively, had SVL/HW ratios greater than 7.2, the presumed upper limit for P. mississippi according to Lazell (1998). Moreover, for the 45 specimens of P. mississippi that Carr (1996) examined, the mean SVL and HW were 60.8 mm and 7.9 mm, respectively, for a mean SVL/HW ratio of 7.7. These findings suggests that the upper limit of the SVL/HW ratio for P. mississippi is considerably higher than 7.2. Thus, the SVL/HW ratios between P. mississippi and P. ainsworthi do not appear to be as disparate as indicated by Lazell (1998). The long-term submersion of the specimens of P. ainsworthi in strong formalin led to the decalcification of their bones and made the specimens very brittle, causing several of the appendages to break off (Lazell 1998). The one specimen of P. mississippi (MMNS #133 from Madison County) that we examined that had a SVL/HW ratio (8.2) within the range reported for P. ainsworthi (7.9–8.4 [Lazell 1998]) was also in very poor condition (e.g., the body was contorted and the vent appeared stretched). Therefore, the SVL/HW ratio calculation for this specimen may have been inaccurate. The very poor condition of the type specimens of P. ainsworthi may have similarly led to the calculation of an inaccurate and abnormally high SVL/HW ratio. Therefore, the SVL/HW ratio reported for P. ainsworthi by Lazell (1998) might have fallen within the range we reported for P. mississippi (Table 1) had the specimens been in better condition. During our sixth and seventh surveys for slimy salamanders at the presumed historic collecting site of P. ainsworthi, we encountered very few individuals, even under “ideal” conditions (i.e., immediately following hard rains). Thus, we had probably collected a large proportion of the individuals comprising this population, and it was unlikely that further collection and subsequent morphological comparisons of additional specimens from this area would have further clarified the status of P. ainsworthi. By contrast, genetic data (such as Nei’s genetic distance [Nei 1972] used by Highton [1989] to erect the P. glutinosus complex) may be used in addition to, or exclusive of morphological data, to differentiate among species. However, additional specimens of P. ainsworthi would be needed for a genetic analysis as the two specimens that were assigned to this species were preserved in strong formalin (and one subsequently destroyed); thus, they are useless for such a procedure. Until the year 2011, two species of amphibians in the United States were considered by the International Union for Conservation of Nature (IUCN) to have become extinct in recent times: P. ainsworthi and Lithobates (Rana) fisheri (Stejneger), the Vegas Valley Leopard Frog (IUCN 2012a) (the IUCN Red List does not include species that became extinct before 1500 AD, see IUCN 2012b). Genetic analyses/comparisons performed by Hekkala et al. (2011) on museum specimens of L. fisheri and other leopard frog populations showed that L. fisheri and the still existing Lithobates (Rana) chiricahuensis (Platz and Mecham) (Chiricahua Leopard Frog) are conspecific. As a result, P. ainsworthi is the only J.G. Himes and D.C. Beckett 2013 Southeastern Naturalist Vol. 12, No. 4 856 amphibian species considered to have become extinct in recent history within the United States. Because long-term preservation in formalin may have resulted in limb shrinkage and other physical deterioration, possibly leading to the distinctively elongated body, the validity of P. ainsworthi as a taxon distinct from P. mississippi is questionable. It remains possible, however, that P. ainsworthi is a distinct species that 1) is now extinct, or 2) still survives but has eluded detection. Given the large number of failed sampling efforts made by multiple sampling groups at the Ainsworth property site, and the lack of any unique topographic or geographic features at the site (the site is a mesic woodland along a hillside within the extensive Southeastern Plains Ecoregion), we think the second possibility is very unlikely. The presence of another species of slimy salamander (besides P. mississippi) in this general area, which has never been collected by anyone other than J. H. Ainsworth, seems improbable. Thus, while we cannot disprove that P. ainsworthi is distinct from P. mississippi, the results of our study provide compelling evidence that P. ainsworthi is not a valid taxon. Acknowledgments We thank J. Lazell for showing us the collection site of P. ainsworthi and M. Ainsworth for granting us permission to survey this site. We also thank R. Jones for allowing us access to specimens of P. mississippi from the MMNS herpetology collection and J. Rosado for loaning us the type specimen of P. ainsworthi from the Harvard University Museum of Comparative Zoology. Mr. and Mrs. J. Lazell, R. W. Van Devender, and E. Ducote provided field assistance. This study was funded by the MMNS through the 2000 Research Grant Program and the Mississippi Wildlife Heritage Fund (Federal Tax I.D. no. 646000818). Literature Cited Carr, D.E. 1996. Morphological variation among species and populations of salamanders in the Plethodon glutinosus complex. Herpetologica 52:56–65. Hekkala, E.R., R.A. Saumure, J.R. Jaeger, H. Herrmann, M.J. Sredl, D.F. Bradford, D. Drabeck, and M.J. Blum. 2011. Resurrecting an extinct species: Archival DNA, taxonomy, and conservation of the Vegas Valley Leopard Frog. Conservation Genetics 12:1379–1385. Highton, R. 1989. Biochemical evolution in the slimy salamanders of the Plethodon glutinosus complex in the eastern United States. Part I. Geographic protein variation. Illinois Biological Monograph 57:1–78. International Union for Conservation of Nature (IUCN). 2012a. IUCN red list of threatened species. Plethodon ainsworthi. Available online at http://www.iucnredlist.org/ details/29488/0. Accessed June 28, 2013. IUCN. 2012b. IUCN red list of threatened species. About. Available online at http://www. iucnredlist.org/about. Accessed June 28, 2013. Lazell, J. 1998. New salamander of the genus Plethodon from Mississippi. Copeia 1998:967–970. Nei, M. 1972. Genetic distance between populations. American Naturalist 106:283–292.