Hyman LH 1937 (citation)- Discussion of this species and confusing it with P. gracilis. She notes: 'I have had specimens of this species from Swan's Island, Maine; it was described by Girard and Woodworth from the vicinity of Cambridge, Massachusetts, where I also have found it; and I have taken typical specimens at New Haven, Connecticut. Material found in a spring-fed stream near Yonkers, New York, has also proved to be P. woodworthi and specimens sent to me from Princeton, New Jersey, through the kindness of Professor Dahlgren of Princeton University, were either identical with New England specimens in the details of the copulatory apparatus or differed slightly from them. The Delaware River therefore constitutes the boundary betweehn P. gracilis and P. woodworthi with some evidence of transitional features in New Jersey material.'
Kenk R 1972 (citation)- p 44, "Northeastern parts of the U.S. north of the Delaware River and eastern Canada as far west as Ontario."
Kenk R 1970 (citation)- p 13, 'Little is known about the ecological requirements of P. woodworthi. It is generally taken in ponds and rivers, more rarely in cold streams and springs. The fact that it often shares its habitat with such eurythermic species as Dugesia tigrina (Girard) and Procotyla fluviatilis Leidy suggests that it tolerates greater temperature fluctuations that does P. gracilis.'
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