PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



issued 



SMITHSONIAN INSTITUTION 

 L). S. NATIONAL MUSEUM 



Vol. 101 Washington: 1951 f^^ 3289 



A NEW SUBSPECIES OF MARINE ISOPOD FROM TEXAS 



By Robert J. Menzies 



Through the courtesy of Joel W. Iledgpeth, formerly of tlie 

 Institute of JSIarine Science, Port Aransas, Tex., I received 12 speci- 

 mens of an idotheid isopod that superficially resemble Erichsonella 

 attenuata (Harger). A comparison of this material with specimens 

 of E. attenuata and E. fdiformis (Say), lent by Dr. Fenner A. Chace, 

 Jr., curator of the division of marine invertebrates. United States 

 National Museum, reveals the fact that the Texas specimens, in 

 spite of their general appearance, are very closely related to E. 

 filijormis. In my opinion, the differences warrant the erection of a 

 new subspecies. 



The descriptions given by Harger and Richardson of E. filijormis 

 are inaccurate in a few important details, and necessary corrections 

 are made in this paper. 



Genus ERICHSONELLA Benedict 



Richardson (1905, p. 400) characterized the genus in part with the 

 statement, "The epimera of all the segments of the thorax, including 

 the first, are distinctly separated from the segments." There is no 

 indication of epimeral separation from the first peraeonal (thoracic) 

 somite in the specimens of E. attenuata and E. filijormis that I have 

 examined, although the epimera of peraeonal somites 2 to 7 are clearly 

 separated from their somites. The male penis is composed of a 

 medially cleft plate (appearing as two separate pieces), and this fact 

 should be added to the generic descriptions of Harger (1880, pp. 

 354-355) and Richardson (1905, p. 400). 



The two subspecies of E. filijormis may be distinguished by the 

 following diagnoses: 



936970—51 575 



