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Type: Article
Published: 2022-07-19
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Nomenclatural solutions for diagnosing ‘cryptic’ species using molecular and morphological data facilitate a taxonomic revision of the Black-bellied Salamanders (Urodela, Desmognathusquadramaculatus’) from the southern Appalachian Mountains

Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
Department of Natural Sciences, Nash Community College, Rocky Mount, NC, 27804, USA
Validity molecular characters availability convergence phenotype Amphibia

Abstract

To be available under the International Code of Zoological Nomenclature, nomina erected after 1930 must “be accompanied by a description or definition that states in words characters that are purported to differentiate the taxon” (Article 13.1.1). For many so-called ‘cryptic’ species, this may prove difficult when relying on external morphology. Yet, such species are likely to be diagnosable by (fixed or variable) differences in DNA sequences, which can also be treated as characters and described in words. While recent authors have proposed such methods, they have rarely been adopted as the primary diagnostic implement in vertebrates. Additionally, morphometrics may reveal subtle but distinct variation in size and shape, which may not be dispositive for identifying individual specimens but can nonetheless characterize overall differences between species. We employ these techniques here to revise the taxonomy of the Black-bellied Salamanders Desmognathus folkertsi and Desmognathus quadramaculatus’ from the southern Appalachian Mountains of the eastern United States. While the former was diagnosed by a variety of morphological and molecular characters, the latter was poorly characterized and subsequently found to consist of two distantly related clades of six genetic lineages. Recent nomenclatural work found that the nomen Salamandra quadramaculata Holbrook, 1840 was unavailable for this species and that no valid nomen had ever been applied at the species level. We erect three new species and resurrect one junior synonym to account for species-level geographic genetic variation in the group. All nomina are diagnosed with explicit reference to fixed or varying allelic differences at mitochondrial and nuclear loci, quantitative variation in overall size and shape from linear morphometrics, and qualitative description of color-pattern variation. Despite their gross similarity, we hypothesize that subtle, as-yet undetected phenotypic variation exists between these species, which may be revealed by geometric morphometrics, 3D scanning, and other data such as physiology and behavior. We also utilize recently developed technologies to present DNA-sequence data for these species in a compact, reproducible format to permanently associate the observed characters with the original description, with several thousand base pairs taking up only a few cm2. These approaches may prove useful for future descriptions of amphibians with highly similar external phenotypes.

References

  1. Anonymous [International Commission on Zoological Nomenclature] (1999) International code of zoological nomenclature. Fourth edition. London (International Trust for zoological Nomenclature): i–xxix + 1–306. <https://doi. org/10.5962/bhl.title.50608>.

  2. Adams, D. C. & Otárola-Castillo, E. (2013) Geomorph: an R package for the collection and analysis of geometric morphometric shape data. Methods in Ecology and Evolution, 4 (4): 393–399. <https://doi.org/10.1111/2041-210X.12035>.

  3. Aguiar, A. P. (2013) Publishing large DNA sequence data in reduced spaces and lasting formats, in paper or PDF. Zootaxa, 3609 (6): 593–600. <https://doi.org/10.11646/zootaxa.3609.6.5>.

  4. Angulo, A. & Reichle, S. (2008) Acoustic signals, species diagnosis, and species concepts: the case of a new cryptic species of Leptodactylus (Amphibia, Anura, Leptodactylidae) from the Chapare region, Bolivia. Zoological Journal of the Linnean Society, 152 (1): 59–77. <https://doi.org/10.1111/j.1096-3642.2007.00338.x>.

  5. Baird, S. F. (1850) Revision of the North American Tailed-Batrachia, with descriptions of new genera and species. Journal of the Academy of natural Sciences of Philadelphia, 2: 281–294.

  6. Bakkegard, K. A. & Rhea, R. A. (2012) Tail length and sexual size dimorphism (SSD) in desmognathan salamanders. Journal of Herpetology, 46 (3): 304–311. <https://doi.org/10.1670/10-307>.

  7. Bauer, A. M., Parham, J. F., Brown, R. M., Stuart, B. L., Grismer, L., Papenfuss, T. J., Böhme, W., Savage, J. M., Carranza, S., Grismer, J. L., Wagner, P., Schmitz, A., Ananjeva, N. B. & Inger, R. F. (2011) Availability of new Bayesian-delimited gecko names and the importance of character-based species descriptions. Proceedings of the royal Society, (B: Biological Sciences), 278: 490–492. <https://doi.org/10.1098/rspb.2010.1330>.

  8. Beachy, C. & Bruce, R. (2003) Life history of a small form of the plethodontid salamander Desmognathus quadramaculatus. Amphibia-Reptilia, 24 (1): 13–26. <https://doi.org/10.1163/156853803763806902>.

  9. Beamer, D. A. & Lamb, T. (2020) Towards rectifying limitations on species delineation in dusky salamanders (Desmognathus: Plethodontidae): an ecoregion-drainage sampling grid reveals additional cryptic clades. Zootaxa, 4734 (1): 1–61. <https://doi.org/10.11646/zootaxa.4734.1.1>.

  10. Berner, D. (2011) Size correction in biology: how reliable are approaches based on (common) principal component analysis? Oecologia, 166 (4): 961–971. <https://doi.org/10.1007/s00442-011-1934-z>.

  11. Bickford, D., Lohman, D. J., Sodhi, N. S., Ng, P. K. L., Meier, R., Winker, K., Ingram, K. K. & Das, I. (2007) Cryptic species as a window on diversity and conservation. Trends in Ecology & Evolution, 22 (3): 148–155. <https://doi.org/10.1016/j.tree.2006.11.004>.

  12. Bingham, R. E., Papenfuss, T. J., Lindstrand, L. & Wake, D. B. (2018) Phylogeography and species boundaries in the Hydromantes shastae complex, with description of two new species (Amphibia; Caudata; Plethodontidae). Bulletin of the Museum of comparative Zoology, 161 (10): 403–427. <https://doi.org/10.3099/MCZ42.1>.

  13. Bishop, S. C. (1928) Notes on some Amphibians and Reptiles from the southeastern states, with a description of a new salamander from North Carolina. Journal of the Elisha Mitchell scientific Society, 43 (3‒4): 153–170.

  14. Bishop, S. C. (1941) Notes on salamanders with descriptions of several new forms. Occasional Papers of the Museum of Zoology, University of Michigan, 451: 1–21.

  15. Bishop, S. C. (1943) Handbook of Salamanders; the Salamanders of the United States, of Canada, and of Lower California. Ithaca, New York (Comstock Publishing Company): i–xiv + 1–555.

  16. Bogart, J. P. (2019) Unisexual salamanders in the genus Ambystoma. Herpetologica, 75 (4): 259–267. <https://doi.org/10.1655/Herpetologica-D-19-00043.1>.

  17. Boulenger, G. A. (1882) Catalogue of the Batrachia Gradientia s. Caudata and Batrachia Apoda in the collection of the British Museum. London (Printed by order of the Trustees): i–vi + 1–127, pl. 1–9.

  18. Brinton, D. G. (1885) The Lenâpé and their legends: with the complete text and symbols of the Walam Olum, a new translation, and an inquiry into its authenticity. Philadelphia (printed for the author): 1–340.

  19. Bruce, R. C. (1993) Sexual size dimorphism in desmognathine salamanders. Copeia, 1993 (2): 313–318. <https://doi.org/10.2307/1447131>.

  20. Bruce, R. C. (1996) Life-history perspective of adaptive radiation in desmognathine salamanders. Copeia, 1996 (4): 783–790. <https://doi.org/10.2307/1447639>.

  21. Burbrink, F. T. & Ruane, S. (2021) Contemporary philosophy and methods for studying speciation and delimiting species. Ichthyology & Herpetology, 109 (3): 874–894. <https://doi.org/10.1643/h2020073>.

  22. Burbrink, F. T., Crother, B. I., Murray, C. M., Smith, B. T., Ruane, S., Myers, E. A. & Pyron, R. A. (2022) Empirical and philosophical problems with the subspecies rank. Ecology and Evolution, in press: <https://doi.org/10.22541/au.164847286.69025170/v1>.

  23. Camp, C., Barbour, M. & Wooten, J. (2014) Morphological differentiation between the larval forms of two cryptic species of dusky salamander (Desmognathus). Amphibia-Reptilia, 35 (1): 117–122. <https://doi.org/10.1163/15685381-00002922>.

  24. Camp, C. D. (2004) Desmognathus folkertsi. Catalogue of American Amphibians and Reptiles, 782: 1–3.

  25. Camp, C. D., Jones, D., Phillips, J., Brock, T. L. & Wooten, J. A. (2022) Differential infection of two sympatric, cryptic species of Appalachian salamander (genus Desmognathus) by the trematode Metagonimoides oregonensis. Comparative Parasitology, 88 (2): 183–186. <https://doi.org/10.1654/COPA-D-21-00008>.

  26. Camp, C. D. & Marshall, J. L. (2006) Reproductive life history of Desmognathus folkertsi (Dwarf Black-bellied Salamander). Southeastern Naturalist, 5 (4): 669–684. <https://doi.org/10.1656/1528-7092(2006)5[669:RLHODF]2.0.CO;2>.

  27. Camp, C. D., Marshall, J. L. & Austin, R. M., Jr. (2000) The evolution of adult body size in black-bellied salamanders (Desmognathus quadramaculatus complex). Canadian Journal of Zoology, 78 (10): 1712–1722. <https://doi.org/10.1139/z00-127>.

  28.  

  29. Camp, C. D., Seymour, Z. L. & Wooten, J. A. (2013) Morphological variation in the cryptic species Desmognathus quadramaculatus (Black-bellied Salamander) and Desmognathus folkertsi (Dwarf Black-bellied Salamander). Journal of Herpetology, 47 (3): 471–479. <https://doi.org/10.1670/11-287>.

  30. Camp, C. D. & Tilley, S. G. (2005) Desmognathus folkertsi Camp, Tilley, Austin and Marshall, 2002 Dwarf Black-Bellied Salamander. In: M. J. Lannoo (ed.), Amphibian declines: the conservation status of United States species, Los Angeles (University of California Press): 706–708.

  31. Camp, C. D., Tilley, S. G., Austin, R. M. & Marshall, J. L. (2002) A new species of Black-Bellied Salamander (genus Desmognathus) from the Appalachian Mountains of northern Georgia. Herpetologica, 58 (4): 471–484. <https://doi.org/10.1655/0018-0831(2002)058[0471:ANSOBS]2.0.CO;2>.

  32. Camp, C. D. & Wooten, J. A. (2016) Hidden in plain sight: cryptic diversity in the Plethodontidae. Copeia, 104 (1): 111–117. <https://doi.org/10.1643/OT-14-150>.

  33. Carstens, B. C., Pelletier, T. A., Reid, N. M. & Satler, J. D. (2013) How to fail at species delimitation. Molecular Ecology, 22 (17): 4369–4383. <https://doi.org/10.1111/mec.12413>.

  34. Caruso, N. & Lips, K. (2013) Truly enigmatic declines in terrestrial salamander populations in Great Smoky Mountains National Park. Diversity and Distributions, 19 (1): 38–48. <https://doi.org/10.2307/23480722>.

  35. Chan, K. O., Hutter, C. R., Wood, P. L., Grismer, L. L., Das, I. & Brown, R. M. (2020) Gene flow creates a mirage of cryptic species in a Southeast Asian spotted stream frog complex. Molecular Ecology, 29 (20): 3970–3987. <https://doi.org/10.1111/mec.15603>.

  36. Chan, K. O., Hutter, C. R., Wood, P. L., Su, Y.-C. & Brown, R. M. (2021) Gene flow increases phylogenetic structure and inflates cryptic species estimations: a case study on widespread Philippine Puddle Frogs (Occidozyga laevis). Systematic Biology, 71 (1): 40–57. <https://doi.org/10.1093/sysbio/syab034>.

  37. Chaplin, K., Sumner, J., Hipsley, C. A. & Melville, J. (2020) An integrative approach using phylogenomics and high-resolution x-ray computed tomography for species delimitation in cryptic taxa. Systematic Biology, 69 (2): 294–307. <https://doi.org/10.1093/sysbio/syz048>.

  38. Che, J., Chen, H.-M., Yang, J.-X., Jin, J.-Q., Jiang, K., Yuan, Z.-Y., Murphy, R. W. & Zhang, Y.-P. (2012) Universal COI primers for DNA barcoding amphibians. Molecular Ecology Resources, 12 (2): 247–258. <https://doi.org/10.1111/j.1755-0998.2011.03090.x>.

  39. Colston, T. J., Noonan, B. P., Smith, M. L. & Pyron, R. A. (2020) Availability of recently described Ptychadena (Anura: Ptychadenidae) nomina from Ethiopia. Zootaxa, 4786 (2): 289–294. <https://doi.org/10.11646/zootaxa.4786.2.11>.

  40. Cope, E. D. (1869) A review of the species of Plethodontidae and Desmognathidae. Proceedings of the Academy of natural Sciences of Philadelphia, 21: 93–118.

  41. Crespi, E. J., Browne, R. A. & Rissler, L. J. (2010) Taxonomic revision of Desmognathus wrighti (Caudata: Plethodontidae). Herpetologica, 66 (3): 283–295. <https://doi.org/10.1655/HERPETOLOGICA-D-09-00002.1>.

  42. Dodd, C. K. (2004) The Amphibians of Great Smoky Mountains National Park. Knoxville (University of Tennessee Press): 1–283. <https://doi.org/10.3133/cir1258>.

  43. Dubois, A. (2011) Species and ‘strange species’ in zoology: do we need a ‘unified concept of species’? Comptes rendus Palevol, 10 (2‒3): 77–94. <https://doi.org/10.1016/j.crpv.2011.01.002>.

  44. Dubois, A. (2017) Diagnoses in zoological taxonomy and nomenclature. Bionomina, 12 (1): 63–85. <https://doi.org/10.11646/bionomina.12.1.8>.

  45. Dubois, A., Pyron, R. A. & Beamer, D. A. (2022) The taxonominal statuses of the nomina Salamandra fusca Green, 1818 and Salamandra quadramaculata Holbrook, 1840 (Amphibia, Urodela). Bionomina, submitted.

  46. Dunn, E. R. (1917) The salamanders of the genera Desmognathus and Leurognathus. Proceedings of the United States national Museum, 53 (2211): 393–433. <https://doi.org/10.5479/si.00963801.53-2211.393>.

  47. Dunn, E. R. (1926) The salamanders of the family Plethodontidae. Northampton, Massachusetts (Smith College): 1–456.

  48. Fedosov, A., Achaz, G., Gontchar, A. & Puillandre, N. (2022) MOLD, a novel software to compile accurate and reliable DNA diagnoses for taxonomic descriptions. Molecular Ecology Resources, 22 (5): 2038–2053. <https://doi.org/10.1111/1755-0998.13590>.

  49. Fišer, C., Robinson, C. T. & Malard, F. (2018) Cryptic species as a window into the paradigm shift of the species concept. Molecular Ecology, 27 (3): 613–635. <https://doi.org/10.1111/mec.14486>.

  50. Fujita, M. K. & Leaché, A. D. (2011) A coalescent perspective on delimiting and naming species: a reply to Bauer et al. Proceedings of the royal Society, (B: Biological Sciences), 278: 493–495. <https://doi.org/10.1098/rspb.2010.1864>.

  51. Goldstein, P. Z. & DeSalle, R. (2011) Integrating DNA barcode data and taxonomic practice: determination, discovery, and description. BioEssays, 33 (2): 135–147. <https://doi.org/10.1002/bies.201000036>.

  52. Gray, J. E. (1850) Catalogue of the specimens of Amphibia in the collection of the British Museum. Part II. Batrachia Gradientia, etc. London (Spottiswoodes & Shaw): 1–72, pl. 3–4.

  53. Green, J. (1818) Descriptions of several species of North American Amphibia, accompanied with observations. Journal of the Academy of natural Sciences of Philadelphia, 1: 348–359.

  54. Hairston, N. G., Sr. (1996) Predation and competition in salamander communities. In: M. L. Cody & J. A. Smallwood (ed.), Long-term studies of vertebrate communities, San Diego, California (Academic Press): 161–189. <https://doi.org/10.1016/B978-012178075-3/50008-8>.

  55. Harrison, R. G. & Larson, E. L. (2014) Hybridization, introgression, and the nature of species boundaries. Journal of Heredity, 105: 795–809. <https://doi.org/10.1093/jhered/esu033>.

  56. Heethoff, M. (2018) Cryptic species—conceptual or terminological chaos? A response to Struck et al. Trends in Ecology & Evolution, 33 (5): 310. <https://doi.org/10.1016/j.tree.2018.02.006>.

  57. Henry, C. S., Wells, M. L. M. & Simon, C. M. (1999) Convergent evolution of courtship songs among cryptic species of the Carnea group of Green Lacewings (Neuroptera: Chrysopidae: Chrysoperla). Evolution, 53 (4): 1165–1179. <https://doi.org/10.1111/j.1558-5646.1999.tb04530.x>.

  58. Hey, J. (2006) On the failure of modern species concepts. Trends in Ecology & Evolution, 21 (8): 447–450. <https://doi.org/10.1016/j.tree.2006.05.011>.

  59. Highton, R. (1995) Speciation in eastern North American salamanders of the genus Plethodon. Annual Review of Ecology and Systematics, 26: 579–600. <https://doi.org/10.1146/annurev.es.26.110195.003051>.

  60. Hillis, D. M., Chambers, E. A. & Devitt, T. J. (2021) Contemporary methods and evidence for species delimitation. Ichthyology & Herpetology, 109 (3): 895–903. <https://doi.org/10.1643/h2021082>.

  61. Hinderstein, B. (1971) Studies on the salamander genus Desmognathus: variation of lactate dehydrogenase. Copeia, 1971 (4): 636–644. <https://doi.org/10.2307/1442632>.

  62. Holbrook, J. E. (1840) North American herpetology; or, A description of the Reptiles inhabiting the United States. [First edition]. Volume 4. Philadelphia (J. Dobson): i–viii + [ix] + [9]+ 10–126, pl. 1–28. <https://doi.org/10.5962/bhl.title.51821>.

  63. Holbrook, J. E. (1842) North American herpetology; or, A description of the Reptiles inhabiting the United States. [Second edition]. Volume 5. Philadelphia (J. Dobson): i–vi + [5] + 6–118 + [i], pl. 1–38. <https://doi.org/10.5962/p.326744>.

  64. Hugall, A. F., Foster, R. & Lee, M. S. Y. (2007) Calibration choice, rate smoothing, and the pattern of tetrapod diversification according to the long nuclear gene RAG-1. Systematic Biology, 56 (4): 543–563. <https://doi.org/10.1080/10635150701477825>.

  65. Huheey, J. E. (1966) The desmognathine salamanders of the Great Smoky Mountains National Park. Journal of the Ohio herpetological Society, 5 (3): 63–72. <https://doi.org/10.2307/1562609>.

  66. Jackson, N. D. (2005) Phylogenetic history, morphological parallelism, and speciation in a complex of Appalachian salamanders (genus: Desmognathus). M.S. Thesis, Provo, Utah (Brigham Young University): 1–64.

  67. Jensen, J. B., Camp, C. D., Gibbons, J. W., & Elliott, M. (2008) Amphibians and Reptiles of Georgia. Athens, Georgia (University of Georgia Press): 1–575.

  68. Jones, K. S. & Weisrock, D. W. (2018) Genomic data reject the hypothesis of sympatric ecological speciation in a clade of Desmognathus salamanders. Evolution, 72 (11): 2378–2393. <https://doi.org/10.1111/evo.13606>.

  69. Jörger, K. M. & Schrödl, M. (2013) How to describe a cryptic species? Practical challenges of molecular taxonomy. Frontiers in Zoology, 10 (59): 1‒27. <https://doi.org/10.1186/1742-9994-10-59>.

  70. Karanovic, T., Djurakic, M. & Eberhard, S. M. (2016) Cryptic species or inadequate taxonomy? Implementation of 2D geometric morphometrics based on integumental organs as landmarks for delimitation and description of copepod taxa. Systematic Biology, 65 (2): 304–327. <https://doi.org/10.1093/sysbio/syv088>.

  71. Korshunova, T., Picton, B., Furfaro, G., Mariottini, P., Pontes, M., Prkić, J., Fletcher, K., Malmberg, K., Lundin, K. & Martynov, A. (2019) Multilevel fine-scale diversity challenges the ‘cryptic species’ concept. Scientific Reports, 9 [6732]: 1–23. <https://doi.org/10.1038/s41598-019-42297-5>.

  72. Kozak, K. H., Larson, A., Bonett, R. M. & Harmon, L. J. (2005) Phylogenetic analysis of ecomorphological divergence, community structure, and diversification rates in Dusky Salamanders (Plethodontidae: Desmognathus). Evolution, 59 (9): 2000–2016. <https://doi.org/10.1111/j.0014-3820.2005.tb01069.x>.

  73. Kozak, K. M., Joron, M., McMillan, W. O. & Jiggins, C.D. (2021) Rampant genome-wide admixture across the Heliconius radiation. Genome Biology and Evolution, 13 (7): evab099. <https://doi.org/10.1093/gbe/evab099>.

  74. Laurenti, J. N. (1768) Specimen medicum, exhibens synopsin Reptilium emendatam cum experimentis circa venena et antidota Reptilium austriacorum. Viennae (Joan. Thom. Nob. de Trattnern): i–ii + 1–215, pl. 1–5. <https://doi. org/10.5962/bhl.title.5108>.

  75. Leaché, A. D. & Fujita, M. K. (2010) Bayesian species delimitation in West African forest geckos (Hemidactylus fasciatus). Proceedings of the royal Society, (B: Biological Sciences), 277: 3071–3077. <https://doi.org/10.1098/rspb.2010.0662>.

  76. León, G. P.-P., de & Nadler, S. A. (2010) What we don’t recognize can hurt us: a plea for awareness about cryptic species. Journal of Parasitology, 96 (2): 453–464. <https://doi.org/10.1645/GE-2260.1>.

  77. Lerner, H. & Tunón, H. (2012) What knowledge is ‘jizz’? Ornis svecica, 22: 73–79. <https://doi.org/10.34080/os.v22.22585>.

  78. Maes, D., Isaac, N. J. B., Harrower, C. A., Collen, B., Strien, A. J. van & Roy, D. B. (2015) The use of opportunistic data for IUCN Red List assessments. Biological Journal of the Linnean Society, 115 (3): 690–706. <https://doi.org/10.1111/bij.12530>.

  79. Mallet, J. (1995) A species definition for the modern synthesis. Trends in Ecology & Evolution, 10 (7): 294–299. <https://doi.org/10.1016/0169-5347(95)90031-4>.

  80.  

  81. Mallet, J. (2008) Hybridization, ecological races and the nature of species: empirical evidence for the ease of speciation. Philosophical Transactions of the royal Society, (B: Biological Sciences), 363: 2971–2986. <https://doi.org/10.1098/rstb.2008.0081>.

  82. Martof, B. (1953) The ‘spring lizard’ industry: a factor in salamander distribution and genetics. Ecology, 34 (2): 436–437. <https://doi.org/10.2307/1930915>.

  83. Martof, B. S. & Rose, F. L. (1963) Geographic variation in southern populations of Desmognathus ochrophaeus. American Midland Naturalist, 69 (2): 376–425. <https://doi.org/10.2307/2422917>.

  84. Mayden, R. L. (1997) A hierarchy of species concepts: the denouement in the saga of the species problem. In: M. F. Claridge, H. A. Dawah & M. R. Wilson (ed.), Species: the units of diversity, London (Chapman & Hall): 381–423.

  85. McCoy, M. W., Bolker, B. M., Osenberg, C. W., Miner, B. G. & Vonesh, J. R. (2006) Size correction: comparing morphological traits among populations and environments. Oecologia, 148: 547–554. <https://doi.org/10.1007/s00442-006-0403-6>.

  86. McDonald, D. (1996) The etymology of ‘jizz’. Canberra Bird Notes, 21: 2–11.

  87. Merritt, D. S. (2005) Analysis of genotypic and phenotypic differences in Desmognathus quadramaculatus across the Southern Appalachians. M.S. Thesis, Huntington, West Virginia (Marshall University): 1–56.

  88. Mills, G. (1996) A study on the life history and seasonal foraging habits of the salamander Desmognathus quadramaculatus Holbrook, in WV. M.S. Thesis, Huntington, West Virginia (Marshall University): 1–122.

  89. Mishler, B.D. & Donoghue, M.J. (1982) Species concepts: a case for pluralism. Systematic Zoology, 31 (4): 491–503. <https://doi.org/10.2307/2413371>.

  90. Moore, J. P. (1899) Leurognathus marmorata, a new genus and species of salamander of the family Desmognathidae. Proceedings of the Academy of natural Sciences of Philadelphia, 51 (2): 316–323.

  91. Moore, J. P. (1900) A description of Microbdella biannulata with especial regard to the constitution of the leech somite. Proceedings of the Academy of natural Sciences of Philadelphia, 52: 50–73.

  92. Moser, W. E., Devender, R. W. V. & Klemm, D. J. (2005) Life history and distribution of the leech Oligobdella biannulata (Moore, 1900) (Euhirudinea: Glossiphoniidae). Comparative Parasitology, 72 (1): 17–21. <https://doi.org/10.1654/4160>.

  93. Neill, W. T. (1948) The status of the salamander Desmognathus quadramaculatus amphileucus. Copeia, 1948 (3): 218. <https://doi.org/10.2307/1438466>.

  94. Noor, M. A. F. (1999) Reinforcement and other consequences of sympatry. Heredity, 83: 503–508. <https://doi.org/10.1038/sj.hdy.6886320>.

  95. Organ, J. A. (1961) Studies of the local distribution, life history, and population dynamics of the salamander genus Desmognathus in Virginia. Ecological Monographs, 31 (2): 189–220. <https://doi.org/10.2307/1950754>.

  96. Paris, C. A., Wagner, F. S. & Wagner, W. H. (1989) Cryptic species, species delimitation, and taxonomic practice in the homosporous ferns. American Fern Journal, 79 (2): 46–54. <https://doi.org/10.2307/1547159>.

  97. Patton, A., Apodaca, J. J., Corser, J. D., Wilson, C. R., Williams, L. A., Cameron, A. D. & Wake, D. B. (2019) A new Green Salamander in the southern Appalachians: evolutionary history of Aneides aeneus and implications for management and conservation with the description of a cryptic microendemic species. Copeia, 107 (4): 748–763. <https://doi.org/10.1643/CH-18-052>.

  98. Petranka, J. W. (2010) Salamanders of the United States and Canada. Washington, DC (Smithsonian Books): 1–587.

  99. Pope, C. H. (1924) Notes on North Carolina salamanders with especial reference to the egg-laying habits of Leurognathus and Desmognathus. American Museum Novitates, 153: 1–16.

  100. Pope, C. H. (1949) The salamander Desmognathus quadramaculatus amphileucus reduced to synonymy. Natural History Miscellanea, Chicago Academy of Sciences, 44: 1–4.

  101. Powell, R., Conant, R. & Collins, J. T. (2016) Peterson field guide to Reptiles and Amphibians of eastern and central North America. Fourth edition. Boston (Houghton Mifflin Harcourt): 1–494.

  102. Pyron, R. A. (2010) A likelihood method for assessing molecular divergence time estimates and the placement of fossil calibrations. Systematic Biology, 59 (2): 185–194. <https://doi.org/10.1093/sysbio/syp090>.

  103. Pyron, R. A. & Beamer, D. A. (2020) The herpetological legacy of Jacob Green and the nomenclature of some North American lizards and salamanders. Zootaxa, 4838 (2): 221–247. <https://doi.org/10.11646/zootaxa.4838.2.4>.

  104. Pyron, R. A. & Beamer, D. A. (2022) A nomenclatural and taxonomic review of the salamanders (Urodela) from Holbrook’s North American Herpetology. Zootaxa, 5134 (2): 151‒196. <https://doi.org/10.11646/zootaxa.5134.2.1>.

  105. Pyron, R. A., Beamer, D. A., Holzheuser, C. R., Lemmon, E. M., Lemmon, A. R., Wynn, A. H. & O’Connell, K. A. (2022a) Contextualizing enigmatic extinctions using genomic DNA from fluid-preserved museum specimens of Desmognathus salamanders. Conservation Genetics, 23: 375–386. <https://doi.org/10.1007/s10592-021-01424-4>.

  106. Pyron, R. A., Duncan, S. C., Burbrink, F. T., O’Connell, K. A. & Beamer, D. A. (2022b) Speciation hypotheses from phylogeographic delimitation yield an integrative taxonomy for Seal Salamanders (Desmognathus monticola). Systematic Biology, in revision.

  107. Pyron, R. A., O’Connell, K. A., Lamb, J. Y. & Beamer, D. A. (2022c) A new, narrowly endemic species of swamp-dwelling dusky salamander (Plethodontidae: Desmognathus) from the Gulf Coastal Plain of Mississippi and Alabama. Zootaxa, 5133 (1): 53–82. < https://doi.org/10.11646/zootaxa.5133.1.3>.

  108. Pyron, R. A., O’Connell, K. A., Lemmon, E. M., Lemmon, A. R. & Beamer, D. A. (2020) Phylogenomic data reveal reticulation and incongruence among mitochondrial candidate species in Dusky Salamanders (Desmognathus). Molecular Phylogenetics and Evolution, 146 [106751]: 1–13, <https://doi.org/10.1016/j.ympev.2020.106751>.

  109. Pyron, R. A., O’Connell, K. A., Lemmon, E. M., Lemmon, A. R. & Beamer, D. A. (2022d) Candidate‐species delimitation in Desmognathus salamanders reveals gene flow across lineage boundaries, confounding phylogenetic estimation and clarifying hybrid zones. Ecology and Evolution, 12 (2) [e8574]: 1‒38. <https://doi.org/10.1002/ece3.8574>.

  110. Queiroz, K., de (2007) Species concepts and species delimitation. Systematic Biology, 56 (6): 879–886. <https://doi.org/10.1080/10635150701701083>.

  111. Ratnasingham, S. & Hebert, P. D. N. (2007) BOLD: the Barcode of Life Data System (http://www.barcodinglife.org). Molecular Ecology Notes, 7 (3): 355–364. <https://doi.org/10.1111/j.1471-8286.2007.01678.x>.

  112. Renner, M. (2020) Opportunities and challenges presented by cryptic bryophyte species. Telopea, 23: 41–60. <https://doi.org/10.7751/telopea14083>.

  113. Renner, S. S. (2016) A return to Linnaeus’s focus on diagnosis, not description: the use of DNA characters in the formal naming of species. Systematic Biology, 65 (6): 1085–1095. <https://doi.org/10.1093/sysbio/syw032>.

  114. Rissler, L. J., Wilbur, H. M. & Taylor, D. R. (2004) The influence of ecology and genetics on behavioral variation in salamander populations across the Eastern Continental Divide. The American Naturalist, 164 (2): 201–213. <https://doi.org/10.1086/422200>.

  115. Rohlf, F. (2015) The tps series of software. Hystrix, the Italian Journal of Mammalogy, 26 (1): 9–12. <https://doi.org/10.4404/hystrix-26.1-11264>.

  116. Rucker, L. E., Brown, D. J., Jacobsen, C. D., Messenger, K. R., Wild, E. R. & Pauley, T. K. (2021) A guide to sexing salamanders in central Appalachia, United States. Journal of Fish and Wildlife Management, 12 (2): 585–603. <https://doi.org/10.3996/JFWM-20-042>.

  117. Semlitsch, R. D., Ryan, T. J., Hamed, K., Chatfield, M., Drehman, B., Pekarek, N., Spath, M. & Watland, A. (2007) Salamander abundance along road edges and within abandoned logging roads in Appalachian forests. Conservation Biology, 21 (1): 159–167. <https://doi.org/10.1111/j.1523-1739.2006.00571.x>.

  118. Sessions, S. K. & Kezer, J. (1987) Cytogenetic evolution in the plethodontid salamander genus Aneides. Chromosoma, 95 (1): 17–30. <https://doi.org/10.1007/BF00293837>.

  119. Smith, M. A., Poyarkov, N. A. & Hebert, P. D. N. (2008) CO1 DNA barcoding amphibians: take the chance, meet the challenge. Molecular Ecology Resources, 8 (2): 235–246. <https://doi.org/10.1111/j.1471-8286.2007.01964.x>.

  120. Southerland, M. T. (1986) Behavioral interactions among four species of the salamander genus Desmognathus. Ecology, 67 (1): 175–181. <https://doi.org/10.2307/1938516>.

  121. Stejneger, L. (1903) Rediscovery of one of Holbrook’s salamanders. Proceedings of the United States national Museum, 26 (1321): 557–558. <https://doi.org/10.5479/si.00963801.1321.557>.

  122. Struck, T. H., Feder, J. L., Bendiksby, M., Birkeland, S., Cerca, J., Gusarov, V. I., Kistenich, S., Larsson, K.-H., Liow, L. H., Nowak, M. D., Stedje, B., Bachmann, L. & Dimitrov, D. (2018a) Cryptic species— more than terminological chaos: a reply to Heethoff. Trends in Ecology & Evolution, 33 (5): 310–312. <https://doi.org/10.1016/j.tree.2018.02.008>.

  123. Struck, T. H., Feder, J. L., Bendiksby, M., Birkeland, S., Cerca, J., Gusarov, V.I., Kistenich, S., Larsson, K.-H., Liow, L. H., Nowak, M. D., Stedje, B., Bachmann, L. & Dimitrov, D. (2018b) Finding evolutionary processes hidden in cryptic species. Trends in Ecology & Evolution, 33 (3): 153–163. <https://doi.org/10.1016/j.tree.2017.11.007>.

  124. Svardal, H., Quah, F. X., Malinsky, M., Ngatunga, B. P., Miska, E. A., Salzburger, W., Genner, M. J., Turner, G. F. & Durbin, R. (2020) Ancestral hybridisation facilitated species diversification in the Lake Malawi cichlid fish adaptive radiation. Molecular Biology and Evolution, 37 (4): 1100–1113. <https://doi.org/10.1093/molbev/msz294>.

  125. Ukuwela, K. D. B., de Silva, A., Mumpuni, Fry, B. G., Lee, M. S. Y. & Sanders, K. L. (2013) Molecular evidence that the deadliest sea snake Enhydrina schistosa (Elapidae: Hydrophiinae) consists of two convergent species. Molecular Phylogenetics and Evolution, 66 (1): 262–269. <https://doi.org/10.1016/j.ympev.2012.09.031>.

  126. Uzzell, T. & Berger, L. (1975) Electrophoretic phenotypes of Rana ridibunda, Rana lessonae, and their hybridogenetic associate, Rana esculenta. Proceedings of the Academy of natural Sciences of Philadelphia, 127: 13–24.

  127. Valentine, B. D. (1974) Desmognathus quadramaculatus (Holbrook). Black-bellied salamander. Catalogue of American Amphibians and Reptiles, 153: 153.1–153.4. <https://doi.org/10.15781/T2XD0R301>.

  128. Watson, M. B., Pauley, T. K. & Camp, C. D. (2005) Desmognathus quadramaculatus Holbrook, 1840 Black-Bellied Salamander. In: M. Lannoo (ed.), Amphibian declines: the conservation status of United States species, Berkeley, California (University of California Press): 708–710.

  129. Wiens, J. J., Bonett, R. M. & Chippindale, P. T. (2005) Ontogeny discombobulates phylogeny: paedomorphosis and higher-level salamander relationships. Systematic Biology, 54 (1): 91–110. <https://doi.org/10.1080/10635150590906037>.

  130. Wiens, J. J., Engstrom, T. N. & Chippindale, P. T. (2006) Rapid diversification, incomplete isolation, and the “speciation clock” in North American salamanders (Genus Plethodon): testing the hybrid swarm hypothesis of rapid radiation. Evolution, 60 (12): 2585–2603. <https://doi.org/10.1111/j.0014-3820.2006.tb01892.x>.

  131. Wood, J. T. (1947) Habitat of Desmognathus quadramaculatus amphileucus. Copeia, 1947 (4): 273. <https://doi.org/10.2307/1438928>.

  132. Wooten, J. A. (2001) Distribution, morphometrics, and tooth morphology of the genus Desmognathus in West Virginia. M.S. Thesis, Huntington, West Virginia (Marshall University): 1–395.

  133. Wooten, J. A., Camp, C. D. & Rissler, L. J. (2010) Genetic diversity in a narrowly endemic, recently described dusky salamander, Desmognathus folkertsi, from the southern Appalachian Mountains. Conservation Genetics, 11: 835–854. <https://doi.org/10.1007/s10592-009-9916-y>.

  134. Wooten, J. A. & Rissler, L. J. (2011) Ecological associations and genetic divergence in Black-bellied Salamanders (Desmognathus quadramaculatus) of the Southern Appalachian Mountains. Acta herpetologica, 6 (2): 175–208. <https://doi.org/10.13128/Acta_Herpetol-9317>.

  135. Wray, K. P., Means, D. B. & Steppan, S. J. (2017) Revision of the Eurycea quadridigitata (Holbrook 1842) complex of dwarf salamanders (Caudata: Plethodontidae: Hemidactyliinae) with a description of two new species. Herpetological Monographs31 (1): 18–46. <http://dx.doi.org/10.1655/HERPMONOGRAPHS-D-16-00011>.

  136. Yang, M. T., 2021. Avian figures and the fluidity of ‘jizz’. ISLE (Interdisciplinary Studies in Literature and Environment), 28 (1): 48–68. <https://doi.org/10.1093/isle/isz082>.

  137. Zúñiga-Reinoso, Á. & Benítez, H. A. (2015) The overrated use of the morphological cryptic species concept: an example with Nyctelia darkbeetles (Coleoptera: Tenebrionidae) using geometric morphometrics. Zoologischer Anzeiger, 255: 47–53. <https://doi.org/10.1016/j.jcz.2015.01.004>.