Thorius, also known as minute salamanders, pigmy salamanders, or Mexican pigmy salamanders, is a genus of salamanders in the family Plethodontidae. They are endemic to Mexico and found in southern Veracruz and Puebla to Guerrero and Oaxaca.[1]
Thorius is the most species-rich tropical salamander genus relative to its distribution area (Bolitoglossa and Pseudoeurycea have many more species but also much wider distribution areas). It is not uncommon for two or even three species to occur in the same place. In such cases, species have diverged in terms of body size and dentition, apparently facilitating niche differentiation.
The members of this genus are characterized by a small body — some species are less than 2cm (01inches) in snout–vent length (tail roughly doubles the total body length). Their extreme miniaturization is accompanied by determinate growth and skeletal reduction. Their skeleton also shows unique features, such as ossifications of many elements that remain cartilaginous in other salamanders. Consequently, they are easy to distinguish from other salamanders. In contrast, they tend to be similar in appearance, making it difficult to distinguish species.[2] However, molecular genetic methods have greatly facilitated identification of new species.[3]
As of November 15, 2016, this genus is composed of the following 29 species:[1] [4] [5]
| Binomial Name and Author | Common Name |
|---|---|
| Thorius adelos | Sierra Juarez salamander |
| Thorius arboreus | Arboreal minute salamander |
| Thorius aureus | Golden minute salamander |
| Thorius boreas | Northern minute salamander |
| Thorius dubitus | Acultzingo minute salamander |
| Thorius grandis | Grand minute salamander |
| Thorius hankeni | Hanken's minute salamander |
| Thorius infernalis | Atoyac minute salamander |
| Thorius insperatus | Vista Hermosa minute salamander |
| Thorius lunaris | Orizaba minute salamander |
| Thorius macdougalli | MacDougall's minute salamanders |
| Thorius magnipes | Big-footed minute salamander |
| Thorius maxillabrochus | Zoquitlan pigmy salamander |
| Thorius minutissimus | Oaxacan minute salamander |
| Thorius minydemus | La Hoya minute salamander |
| Thorius munificus | McDiarmid minute salamander |
| Thorius narismagnus | San Martin minute salamander |
| Thorius narisovalis | Upper Cerro minute salamander |
| Thorius omiltemi | Omiltemi minute salamander |
| Thorius papaloae | Papalo minute salamander |
| Thorius pennatulus | Veracruz minute salamander |
| Thorius pulmonaris | Lower Cerro minute salamander |
| Thorius schmidti | Schmidt's minute salamander |
| Thorius smithi | Smith's minute salamander |
| Thorius spilogaster | Spotted minute salamander |
| Thorius troglodytes | Taylor's minute salamander |
| Thorius pinicola | Pine-dwelling minute salamander |
| Thorius longicaudus | Long-tailed minute salamander |
| Thorius tlaxiacus | Heroic minute salamander |