Not many details of the reproduction of E. sosorum are known. This is due to the secretive and nocturnal nature of salamanders in general. In the wild, females have been found holding, at the maximum, forty eggs from September through January. It is known that females carry their eggs for a year before depositing them It takes one year for larvae to reach sexual maturity and all sexually mature individuals that have been found have been longer than 22.5 mm. Also in their native habitat, young hatchlings have been found in November, March and April. This evidence suggests that breeding takes place year round. In the wild, no deposited eggs have ever been found or seen. It is believed the E. sosorum may deposit it's eggs in the Edwards Aquifer which feeds the pools where they live. The Edwards Aquifer is a karst aquifer which means that it is very porous. Due to the small size of the salamander this hypothesis could be true. However, in captivity Barton Spring salamanders deposit their eggs on plastic plants in string-like clusters. The eggs are 1.5 mm in diameter and are surrounded by two jelly layers. They are easily observed because of their white color and iridiscent properties.
(Deanna Chamberlain, personal communication; Bishop 1967; Petranka 1998)
As of 1999, in captive-breeding programs, females have deposited eggs twenty times. Of the eggs deposited, larvae only developed twice and none survived to sexual maturity. What has been noted in the embryos is that after 19 days eyes develop and then, after 38 days, limb bud and gill structure is observed.
(Deanna Chamberlain, personal communication)
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate)