Proceedings of 

 the United States 

 National Museum 



SMITHSONIAN INSTITUTION • WASHINGTON, D.C. 



Volume 124 1967 Number 3631 



Status of Genera Branchiobdella and Stephanodrilus 



in North America with Description of a New Genus 



(Clitellata: Branchiobdellida) 1 



By Perry C. Holt 2 



Visiting Research Associate, Department oj Invertebrate Zoology- 



Ill a previous paper (Holt, 1960), the status of one North American 

 species of the branchiobdellid worms that had been assigned by an 

 earlier worker to a non-American genus was clarified. An attempt is 

 made here to establish the generic affinities of the remaining North 

 American branchiobdellids that have been placed in Asiatic or Eu- 

 ropean genera. There are three of these: Branchiobdella tetradonta 

 Pierantoni, 1906; Branchiobdellida americana Pierantoni, 1912; Stepha- 

 nodrilus obscurus Goodnight, 1940. Since one of the areas of intrinsic 

 interest in the study of the branchiobdellids is a consideration of their 

 zoogeography, it is important to determine if these species are as- 

 signed correctly and, hence, if there are defensible cases of multiconti- 

 nental generic ranges among them. 



A brief reference has been made to this problem before and attention 

 has been directed to the general relationships of the branchiobdellid 

 fauna of North America to those of Asia and Europe (Holt, 1964). It 

 is not beyond credibility that representatives of the same genus might 

 occur in eastern Asia and in eastern North America as is reputed to be 

 the case for one of the species I am considering herein: my studies 



1 Supported by grant GB 372 from the National Science Foundation. 



2 Department of Biology, Virginia Polytechnic Institute, Blacksburg, Va. 



1 



