It has a worm-like body, a large head and large limbs, and an elongate cylindrical tail of less than 1.5 times its body length.

An adult salamander is between 3 and 5 cm long.

It has a black dorsum with white, coppery, and orange blotches, and an immaculate black venter.

B. gabrieli is similar to the related species B. pacificus and B. nigriventis.

This species is only known from the San Gabriel Canyon system, and typically lives above 1,000 meters in the San Gabriel Mountains of Los Angeles County.