text: Gestation and reproduction Alpine salamanders live in a sex ratio of 1:1. Mating occurs on land. The male clasps the female at the forelegs, and fertilization is internal. S. atra are categorized as viviparous, meaning that their young are born alive and unlike many other amphibians, do not go through metamorphosis They give birth to 2 young, sometimes 3 or 4. New young alpine salamanders may measure as long as  at birth, with the mother measuring only .
  Female alpine salamanders have uteruses that are composed of a single luminal epithelial cell layer, connective tissue, and smooth muscle. The uterine eggs are large and numerous, but, as a rule, only one fully develops in each uterus. The embryo is nourished on the yolk of the other eggs, which more or less dissolve to form a large mass of nutrient matter. The egg mass can be as long as between 25 mm and 40 mm long. The embryo passes through three stages:
  The first stage is when they are still enclosed within the egg and living on its own yolk.
  The second stage is when they are free, within the vitelline mass, eating it directly with their mouths.
  The final stage occurs when there is no more vitelline mass. The embryo is possessed of long external gills, which serve as an exchange of nutritive fluid through the maternal uterus, these gills functioning in the same way as the chorionic villi of the mammalian egg.