Description
Isthmura corrugata is a species of large, muscular plethodontid salamander currently known from a single locality in central Veracruz, Mexico. There are only two described specimens, which have snout-vent length measurements of 71.9 mm and 85.3 mm and total length measurements of 120.2 mm and 145.5 mm. The large, prominent head is broad with very distinct jaw musculature. The snout is rounded with a large, oval mental gland. The nasolabial protuberances are not well developed. The eyes protrude. A deep postorbital groove connects the eye to the end of the jaw and extends to the gular region. The paratoid glands are well developed. The neck is narrower than the head and defined by a deep groove posterior to the head. Maxillary teeth range from 62 – 60 teeth, while vomerine teeth number between 42 – 46. Both specimens have 13 well-defined costal grooves, including one each on the axilla and groin, giving the species 7587 a bumpy, segmented appearance. The limbs are long and robust and the digits are short, yet well-defined, and triangular in shape. The fingers have relative lengths of III < II < IV < I and the toes have relative lengths of III < IV < II < V < I. The hands have a phalangeal formula of 1 – 2 – 3 – 2 and the feet have a formula of 1 – 2 - 3 – 3 – 2. The base of the short tail is constricted and the tip is rounded (Sandoval-Comte et al. 2017).

Isthmura corrugata differs from all other bolitoglossines except Pseudoeurycea papenfussi by its bulging costal folds. Its larger size distinguishes it from all species in the genus Aquiloeurycea, and the presence of a sublingual fold distinguishes it from similarly sized species of Bolitoglossa. It differs from robust species of Pseudoeurycea by having more substantial foot webbing and triangularly shaped toes. It is the second smallest Isthmura, however, because both specimens are male, and female Isthmura are typically larger than males, it is possible their maximum size may be greater than currently recorded. Isthmura corrugata is unique from other Isthmura species due to the lack of spots or marking on the dorsum, as well as its relatively larger head and shorter tail (Sandoval-Comte et al. 2017).

In life, I. corrugata is uniformly dark brown from tail to head, as well as on the hands and feet. The eyelids, jaw margins, and gular surface are a light rufous color, while the proximal half of the flanks are a deep wine red that extends to the venter and ventral side of the limbs. Coloration in alcohol is very similar to that in life, only paler (Sandoval-Comte et al. 2017).

Variation cannot be quantified until more individuals of this species are found.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

Isthmura corrugata is only known from its type locality near the city of Coatepec in the mountainous region of central Veracruz, Mexico at 2106 m above sea level. Both specimens were collected in montane cloud forest, where fog maintains high levels of humidity and a deep layer of leaf litter covers the forest floor (Sandoval-Comte et al. 2017).

It is possible that I. corrugata may inhabit additional localities around Cofre de Perote, extending to Sierra Norte de Puebla near Cuetzalan. These areas share a high proportion of amphibian fauna (Sandoval-Comte et al. 2017).

Life History, Abundance, Activity, and Special Behaviors
Very little is known about the life history of I. corrugata. The holotype was discovered active on the forest floor at night, while the paratype was found inactive under a layer of leaf litter during the day (Sandoval-Comte et al. 2017).

Other amphibian species found in sympatry with I. corrugate include Aquiloeurycea cafetalera, Parvimolge townsendi, Thorius pennatulus, Pseudoeurycea lynchi, and Chiropterotriton chiropterus (Sandoval-Comte et al. 2017).

Trends and Threats
The conservation status of I. corrugata cannot be assessed as there is currently no information on its natural history or population size. Isthmura corrugata is rare. However, it is possible this species is difficult to detect due to its behavior (Sandoval-Comte et al. 2017).

Although the type locality is within a municipal protected reserve, the region is threatened by logging and agricultural activities. Many plethodontid species found on the eastern slope of Cofre de Perote are in high-risk IUCN’s Red List categories. The habitat in which I. corrugata lives is thus a high priority for plethodontid salamander conservation (Sandoval-Comte et al. 2017).

Comments
The species authority is: Sandoval-Comte, A., Pineda, E., Rovito, S.M., Luría-Manzano, R. (2017). “A new species of Isthmura (Caudata: Plethodontidae) from the montane cloud forest of central Veracruz, Mexico.” Zootaxa, 4277 (4), 189-198.

Based on Maximum Likelihood and Bayesian analyses of 16S and cytb mitochondrial DNA sequences, I. corrugate is sister to the clade composed of I. boneti and I. maxima (Sandoval-Comte et al. 2017).

The genus Isthmura was formerly considered part of the Pseudoeurycea bellii complex (Parra-Olea et al. 2005) before being recognized as an independent genus (Rovito et al. 2015).

The specific epithet “corrugata” is a reference to their corrugated appearance (Sandoval-Comte et al. 2017).

References

Parra-Olea, G., Garcia-Paris, M., Papenfuss, T. J. and Wake, D. B. (2005). ''Systematics of the Pseudoeurycea bellii (Caudata: Plethodontidae) species complex.'' Herpetologica, 61, 145-158.

Rovito, S.M., Parra-Olea, G., Recuero, E., Wake, D.B. (2015). ''Diversification and biogeographical history of Neotropical plethodontid salamanders.'' Zoological Journal of the Linnean Society, 175, 167-188.

Sandoval-Comte, A., Pineda, E., Rovito, S.M., Luría-Manzano, R. (2017). ''A new species of Isthmura (Caudata: Plethodontidae) from the montane cloud forest of central Veracruz, Mexico.'' Zootaxa, 4277(4), 189-198.

Species Account Citation: AmphibiaWeb 2018 Isthmura corrugata: Corrugated Salamander; Salamandra corrugada <https://amphibiaweb.org/species/8637> University of California, Berkeley, CA, USA. Accessed Jan 24, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Jan 2025.

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