1. Prorhynchus tasmaniensis sp. nov. is found under alpine conditions in Tasmania.
2. It is allied to Prorhynchus putealis Haswell, but exhibits the following differences: (a) Larger size, (b) Posterior excretory canal does not bifurcate, (c) Female genital pore almost in line with excretory pores and below pharynx, (d) Female genital pore only one-eighth of body-length from anterior end. (Difference from all other members of the genus.) (e) Germo-vitellarium in middle line ventral to intestine. (f) Testis follicular, extending from the right side over the intestine on to the left side. (Difference from all other members of the genus.)