PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



by the 



SMITHSONIAN INSTITUTION 



U. S. NATIONAL MUSEUM 



Vol.106 Washington: 1956 No. 3371 



EMENDED DESCRIPTION AND ASSIGNMENT TO THE NEW 



GENUS RONALEA OF THE IDOTHEID ISOPOD 



ERICHSONELLA PSEUDOCULATA BOONE 



By Robert J. Mejnzies and Thomas E. Bowman 



In 1923 Boone described a new species of idotbeid isopod from 

 San Pedro, Cabf., under tbe name Erichsonella -pseudoculata. Boone's 

 single specimen was a male. More recently a second specimen, this 

 time a female, was collected from Phyllospadix at La Jolla, Calif. In 

 all known species of Erichsonella the abdomen is unisegmental, without 

 partial sutures at tbe base. Boone's species, although otherwise 

 fitting nicel.y into Erichsonella , has partial sutures at the base of the 

 abdomen. We are therefore faced with the alternatives of expanding 

 the definition of Erichsonella or erecting a new genus for pseudoculata. 

 Since tbe number of partial or complete sutures at the abdominal base 

 appears to be constant at the generic level in idotheid isopods, we 

 have elected to establish a new genus, Ronalea, for Boone's species. 



In the genus Eusymmerus Richardson (1889, p. 852) the abdomen 

 also has one partial suture at its base, but it differs from the new 

 genus in that the coxal plates, visible in dorsal view, are separated 

 only in pereion segments 6 and 7. In Ronalea the coxal plates are 

 separated in pereion segments 2-7 as in Erichsonella, but are visible 

 in dorsal view only in segments 5-7. Moreover, the general body 



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