The Morphology and Life History of Hymanella retenuova, a New Species of Triclad from New England

Abstract

In April 1937, two collections of debris from a vernal pond near Brown University yielded a total of 25 planarians which did not appear to belong to any of the species known by me to occur in that region. Following a futile attempt to feed these worms on crushed tadpoles they died after a sojourn of but a few days in the laboratory. Two subsequent collections made during the spring of 1937 yielded some 30 additional specimens which survived up to 17 days in the laboratory and deposited over 40 egg capsules. The peculiar retention of fully formed egg in the bodies of the worms for several days, the oblong shape of the and the lack of an attachment stalk, together with the general shape and appearance of the planarians led me to conclude that a new species was at hand. This was confirmed by Miss L. H. Hyman. who after examination of sections and reconstructions of the copulatory apparatus which I had sent to her was also of the opinion that a new genus was necessitated for the animal. Miss Hyman also called my attention to an article by Chidester (1908) on the extrusion of winter egg capsules by a planarian which he identified as Planaria simplicissima ( = Curtisia foremanii). Chidester's description and figures show at once that the planarium he observed could not possibly have been Curtisia foremanii, and I am convinced that it was identical with the form herein described.