The imagery on this page is the basis for a paper entitled Taxonomic status of the enigmatic salamander Cryptotriton adelos (Amphibia: Plethodontidae) from northern Oaxaca, Mexico, with observations on its skull and postcranial skeleton by D.B. Wake, S.M. Rovito, J.A. Maisano and J. Hanken (2012, Zootaxa, 3579, 67-70). The Introduction is as follows:
Papenfuss and Wake (1987) described a new species of plethodontid salamander from northern Oaxaca, Mexico, which they named Nototriton adelos. The species was assigned to Nototriton primarily on the basis of its similarity to members of that widespread genus, which as then constituted ranged from Oaxaca, Mexico, to east-central Costa Rica. At that time, Nototriton had no unique synapomorphies but rather included diminutive species that could be excluded from membership in all other genera. Wake and Elias (1983), who erected Nototriton, acknowledged that the genus might eventually be shown to be paraphyletic, but they were unable to further resolve the phylogeny with information then available. The original description of N. adelos was based on the holotype and three paratypes; in the subsequent 25 years, despite many futile attempts, only one additional specimen of this species has been discovered: UTAVC A-3956, the largest known specimen, a female, 25.6 mm snout-vent length, from near the type locality.
From the start, assignment of the species to Nototriton was problematic on zoogeographic grounds: it was the only member of its genus from north of the Isthmus of Tehuantepec in southeastern Mexico. Later, when DNA sequence data demonstrated conclusively the paraphyly of Nototriton, N. adelos was transferred to the newly erected genus Cryptotriton (García-París & Wake 2000), but in the absence of sequence data for this species. Once again, however, C. adelos was the only member of its genus from north of the Isthmus of Tehuantepec.
Hanken’s (1983) study of allozymic variation in the endemic Mexican plethodontid genus Thorius included a single specimen of Cryptotriton adelos, but Papenfuss and Wake (1987) subsequently argued that this specimen, and the species to which it belongs, was not a member of Thorius. Cryptotriton adelos lacks the unique subocular groove (orbitolabial groove; Taylor 1944), which intercepts the upper lip and gives a characteristic and distinctive lateral profile to the head in all known species of Thorius (Taylor 1940, Plate XLVII; Gehlbach 1959, Fig. 1).
All efforts to collect more specimens of C. adelos have been fruitless, thereby precluding additional molecular analyses that might help resolve the species’ generic assignment. We therefore decided to examine the osteology of the species by using high-resolution X-ray computed tomography (CT) in an attempt to discover skeletal features that might be phylogenetically informative. Digital scans of a single adult specimen (MVZ 208582, a male, 23.8 mm snout-vent length; www.digimorph.org/specimens/Thorius_adelos) reveal a combination of characters, which while unusual for Thorius in some respects includes features that otherwise are unique to that genus. Furthermore, the osteology of C. adelos excludes it from membership in any other clade of tropical plethodontids. Accordingly, we reassign the species as follows:
Thorius adelos (Papenfuss & Wake 1987)
Nototriton adelos Papenfuss & Wake 1987, p. 7
Cryptotriton adelos (Papenfuss & Wake 1987), García-París & Wake 2000, p. 58
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