Salamandra atra Laurenti, 1768

Scientific Naming

The alpine salamander, scientifically named Salamandra atra Laurenti, 1768, is typically small in size, with a base coloration of dark brown or black.

Base Coloration

Subspecies are not entirely monochrome black or brown, instead displaying mosaic or spotted patterns.

Subspecies Markings

The subspecies Salamandra atra aurorae has bright splotches on its dorsal side and head; these markings are most often bright yellow, but can also range into shades of white or gray.

Marking Variation

The distribution of this pigment depends on the arrangement of specific cells, so the markings may be smooth and even or uneven and patchy.

Size Dimorphism

Female alpine salamanders are usually larger than males, growing up to 151 millimeters (around 5.9 inches), while males reach approximately 144 millimeters (5.6 inches); both measurements include the tail.

Male Morphology

Males have swollen, visible cloacae and a more slender body shape than females.

Parotid Glands

These salamanders have parotid glands located posterior and lateral to the eyes, which gives their heads an elongated shape.

Body Gland Structure

They typically have between 11 and 13 costal grooves along their body sides, and a double row of dorsal glands runs down either side of the spine, extending all the way to the tip of the tail.

Terrestrial Habit

Alpine salamanders are fully terrestrial organisms that live on land.

Shelter Sites

They usually shelter under stones or logs, or within rocky crevices in their mountainous habitat.

Activity Pattern

They are primarily diurnal, meaning they are most active during the day and rest or are inactive at night, though they may become active at night depending on weather conditions.

Ideal Environmental Conditions

Ideal conditions for alpine salamanders are rainy or post-rain weather, with temperatures between 3 and 18 °C (37.4 and 64.4 °F).

Geographic Range Extent

The geographic range of the alpine salamander extends from the France–Switzerland border at its western end, east through Austria to the Dinaric Alps at its eastern edge.

Elevation Range

This species typically occurs at altitudes above 700 metres (2,300 ft) above sea level, and can be found as high as 2,000 metres (6,600 ft) of elevation.

Closely Related Species

A closely related species, Lanza's alpine salamander (Salamandra lanzai), inhabits a single small area of the western Alps in France and Italy.

Occupied Biomes

Alpine salamanders generally occupy forested biomes, particularly mixed deciduous-coniferous forests, and can also live in mountain meadows or grasslands, thriving in areas with a mix of tree types.

Range Countries

Their range spans multiple countries: Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Kosovo, France, Italy, Austria, Algeria, and Switzerland.

Preferred Forest Habitats

They thrive specifically in forest environments with silver fir and beech trees, and also survive well in coniferous forests with high proportions of Norway spruce and European larch, as they live on the forest ground floor.

Territorial Site Fidelity

Because alpine salamanders are completely terrestrial, they maintain on-land territories that they return to throughout the day for refuge, and often return to the same sites for most of their lives.

Risks of Site Abandonment

Leaving these sites exposes them to predation and increases their risk of losing the site entirely.

Ectothermy and Shelter Dependence

Since alpine salamanders are ectothermic, they cannot internally regulate their body temperature, so losing a refuge or shelter can leave them exposed to unfavorable conditions and be extremely costly, even fatal.

Territorial Behavior Evidence

This high dependence on high-quality refuge sites supports the theory that many terrestrial salamanders, including S. atra, exhibit territorial behaviors.

Movement Range

Data from capture-recapture studies shows the species is very stationary: the maximum distance recorded for an individual during the summer season was 12 metres (39 ft).

Population Density

Population counts in most suitable habitats find around 120 individuals per hectare, and counts of over 2000 individuals per hectare have also been observed, indicating this rather cryptic species is quite abundant.

Sex Ratio

The sex ratio of alpine salamanders is 1:1.

Mating Process

Mating occurs on land, with the male clasping the female at the forelegs, and fertilization is internal.

Reproductive Mode

S. atra is viviparous, meaning young are born alive and do not undergo metamorphosis unlike many other amphibians.

Litter Size

Females give birth to 2 young, and sometimes 3 or 4.

Newborn Size

Newborn alpine salamanders can measure up to 50 millimetres (2 in) long at birth, even when the mother is only 120 millimetres (4.7 in) long.

Uterus Structure

The uterus of a female alpine salamander is made up of a single luminal epithelial cell layer, connective tissue, and smooth muscle.

Embryo Development Basics

Uterine eggs are large and numerous, but as a rule only one embryo fully develops in each uterus.

Egg Nutrient Source

The developing embryo is nourished by the yolk of the other eggs, which dissolve more or less completely to form a large mass of nutrient matter.

Nutrient Mass Size

This nutrient egg mass can reach 25 to 40 mm in length.

Developmental Stages Overview

The embryo goes through three distinct developmental stages.

First Developmental Stage

In the first stage, the embryo remains enclosed within its own egg and survives on its own yolk.

Second Developmental Stage

In the second stage, the embryo is free within the vitelline nutrient mass, and eats the mass directly with its mouth.

Third Developmental Stage

In the final third stage, the vitelline mass is completely consumed.

Embryonic Gill Function

At this stage, the embryo has long external gills that exchange nutritive fluid through the mother's uterus, functioning similarly to the chorionic villi of a mammalian embryo.

Gestation Period by Elevation

Generally, at altitudes of 650–1,000 metres (2,130–3,280 ft) above sea level, pregnancy lasts two years; at altitudes of 1,400–1,700 m above sea level, pregnancy lasts around three years.

Standard Gestation Range

Overall, gestation periods ranging from two to four years are considered standard.

Unique Nutrient Acquisition

Alpine salamander embryos have a unique method of obtaining nutrients during their long gestation period.

Oophagy Process

After the embryos have consumed the unfertilized eggs (a process called oophagy, covering stages 1 and 2), a portion of the mother's uterine wall provides nourishment.

Epitheliophagy Process

They then undergo epitheliophagy, the third stage, where they ingest cells from the mother's zona trophica uterine wall layer until birth.

Specialized Feeding Structures

They have specialized tooth-like structures that allow this feeding without harming the mother.