Redescription of the duck leech, <i>Theromyzon rude</i> (Baird, 1869) (Rhynchobdellida: Glossiphoniidae)

Abstract

The identification of the species of Theromyzon in North America and worldwide is based on the number of annuli separating the male and female gonopores. The first species identified from North America (Glossiphonia rudis) was not fully described but, based on the collection of a specimen from the same site, T. rude was subsequently thought to have three annuli between the gonopores. The syntypes of G. rudis were examined. One was identified as Placobdella ornata and the second as a Theromyzon which becomes the holotype of G. rudis on which a new description of T. rude is presented. Theromyzon rude has the gonopores separated by two annuli. The male atrium is spherical, with the undifferentiated terminal ends of the paired male ducts joining before entering the atrium. The vagina is short and vertical. Specimens of Theromyzon with three annuli between the gonopores and previously identified as T. rude clearly must belong to a different species.