Four-toed Salamander

Hemidactylium scutatum (Temminck and Schlegel, 1838)

four-toed salamander

Key Characters: 4 rather than 5 toes on hind feet; circular constriction at base of tail.

Similar Species: Juvenile Eastern Newt, juvenile Spotted Dusky Salamander, Red-backed Salamander, Northern Zigzag Salamander. See Key to Adult and Larval Salamanders of Illinois for help with identification.

Subspecies: None recognized.

four-toed salamander

Description: A small (up to 10 cm TL), slender, reddish brown salamander with a black-spotted ivory-white belly. Costal grooves extend to midline of back. Snout distinctly pale brown. Some individuals have a broad pale brown stripe down midback. Tail breaks off easily.

four-toed salamander

Habitat: Boggy pools or spring-fed ravines in undisturbed or mature deciduous forests. Several localities are second-growth woods in soggy soil below dams of man-made lakes.

Natural History: Terrestrial adults occupy moist, rotten logs and feed on a variety of arthropods on forest floor. Mating occurs in autumn, before hibernation. During April – May, female broods 20-60 moderately large (2.5-3 mm diameter) eggs laid in a cavity a few inches above water within mats of moss or leaves, within logs, under rocks, or along spring-fed streams or pools. Within two months, hatchlings fall or wriggle into water where they develop into high-finned aquatic larvae.

Distribution Notes: Since the publication of Smith (1961), almost a dozen new locations have been documented for H. scutatum, and they have been throughout the state. More populations are likely to be discovered.

Status: Threatened in Illinois. A few scattered localities are relics of post-glacial times when range was more continuous and northern forests covered much of Illinois. Populations in Cook and Lake counties probably extirpated by habitat destruction.

EtymologyHemidactylium -hemi (Greek) for half; daktylos (Greek) finger, daktylikos (Greek) ‘of the finger’; scutatum – sctutatus (Latin) for shield-shaped, ‘armed with a shield’.

Original Description: Temminck, C. J., and H. Schlegel. 1838. Fauna Japonica sive Descriptio animalium, quae in itinere per Japonianum, jussu et auspiciis superiorum, qui summum in India Batava Imperium tenent, suscepto, annis 1823-1830 colleget, notis observationibus et adumbrationibus illustratis. Volume 3 (Chelonia, Ophidia, Sauria, Batrachia) [Leiden]: J. G. Lalau.

Type Specimen: Holotype, RMNH 2301.

Type Locality: “Nashville, Tenn.” = Davidson County, TN, USA.

Original Name: Salamandra scutata Temminck and Schlegel, 1838

Nomenclatural History: H. scutatum was transferred to several genera including Cotobotes, Desmodactylus, Batrachoseps, before being transferred to the current genus, Hemidactylium by Dunn (1926, Salamanders of the Family Plethodontidae:196).  One junior synonym, Salamandra melanosticta Gibbes (1845, Boston J. Nat. Hist., 5: 89) exists.  It was synonymized by Baird, 1850 “1849”, J. Acad. Nat. Sci. Philadelphia, Ser. 2, 1: 286.