Vol. XXVIII, pp. 95-100 April 13, 1915 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



NEW FRESH-WATER CRABS (PSEUDOTHELPHUSA) 



FROM COLOMBIA.* 



BY MARY J. RATHBUN. 



The material described forms part of the collection obtained 

 by the Walker Expedition which was sent by the University of 

 Michigan to Santa Marta, Colombia, in 1913. The Crustacea 

 as a whole will be reported on by Dr. A. S. Pearse. As, how- 

 ever. Doctor Pearse lacks a reference collection of Potamonidse 

 with which to compare the species of Pseudothelphusa, he has 

 turned over to me the specimens of that genus for description. 

 The new forms will be figured in Doctor Pearse's report. 



The species here described all possess a type of maxilliped 

 which exists only in Colombia, Ecuador, Peru, and Bolivia; 

 the merus is subtriangular, its outer margin being straight or a 

 little concave, not broadly rounded as in species from Mexico, 

 Central America, the West Indies, and some parts of South 

 America, including Colombia. 



Pseudothelphusa pearsei sp. nov. 



Hololype. — Adult male, Cat. No. 45,872, Museum of Zoology, Univer- 

 sity of Michigan, Ann Arbor, Michigan. Collected at the Cincinnati 

 Coffee Plantation, Santa INIarta Mountains, Colombia, 4500 feet elevation, 

 under log, by Dr. A. S. Pearse, July 2, 1913. Orig. No. 7. 



Measurements. — Holotype male, length of carapace on the median line 

 19.6 mm., width of carapace 33.2 mm., width between outer angles of 

 orbits 20 mm., width of front above, between the eyes, 10 mm., length 

 of larger propodus below 26 mm., greatest height of palm (near middle) 

 9.6 mm., greatest thickness of palm 7.1 mm., length of dactylus of 

 clieliped 13.2 mm. 



• Published by permission of Dr. A. G. Ruthven, Director of the Museum of Zoology, 



University of Michigan. 



15— Proc. Biol. Soc. Wash., Vol. XXVIII. 1915. (95) 



