The morphology and life-history of Hymanella retenuova, a new species of triclad from New England

HYMANELLA (Planariidae) is defined and one species, H. retenuova, is described from vernal ponds and a spring-fed swampy stream in Seekonk, Massachusetts. In vernal ponds the species is present during the winter and spring and becomes sexually mature. The fully formed, stalkless egg capsules are retained in the body of the parent worm for a period before being deposited. In vernal ponds in nature these egg capsules apparently remain dormant during the summer and early autumn to hatch when water is again in the ponds in the late fall or early winter. The capsules resist exptl. attempts to induce their hatching in the early weeks folowing their deposit, but young worms emerge after a resting period of some 2 months or more. The species is markedly protandrous, and in some morphological and ecological features shows similarities to spp. of Phagocata and Curtisia.