Normal Stages of Development of a Hynobiid Salamander, Hynobius nigrescens Stejneger

Abstract

A table for the normal stages of development of a hynobiid salamander, Hynobius nigrescens Stejneger, is presented. The materials used in the present study were collected from a breeding pond in Iwamuro-mura, Niigata Prefecture. The eggs were ca. 2.6mm in diameter. The larvae were fed on Tubifex. Under a constant temperature of 17°C, the larvae metamorphosed at the age of 80 days. and the total length of these metamorphosed animals was 53.4mm on the average. The ratio of body length, measured from the tip of the snout to the posterior angle of the vent, to total length in the metamorphosed animals was 58.3% on the average in 63 individuals. The process of development from just after spawning till the completion of metamorphosis is here divided into 73 stages. External characteristics in each stage are described in tabular form, and illustrated with sketches.