TERRESTRIAL ISOPODS COLLECTED IN COSTA RICA BY 

 MR. PICADO, WITH THE DESCRIPTION OF A NEW 

 GENUS AND SPECIES. 



By Harriet Richardson, 



Collaborator, Division of Marine Invertebrates, United States National Museum. 



Some terrestrial isopods collected in Costa Rica by Mr. C. Picado 

 were sent by Mr. J. F. Tristan to the United States National Museum 

 for determination. They were found on epiphytic plants of the 

 family Bromeliaceae ("wild pines") and were mostly collected at an 

 altitude of 2,000-2,500 meters. Among them are some specimens 

 representing a new genus of Oniscidae. 



Other terrestrial isopods collected in Costa Rica by Mr. J. F. 

 Tristan were also sent to the United States National Museum about 

 the same time. These were collected in the Bromelias in the old crater 

 of " Reventado " near the Volcano Irazu. Mr. Tristan writes that the 

 old crater is covered with forest. 



Family ONISCID^. 



PENTONISCUS, new genus. 



Body with the abdomen abruptly narrower than the thorax. 



Head with median and antero-lateral lobes small. 



Second antennae with a flagellum composed of five articles, the 

 third and fourth rather indistinctly separated. 



Mouth parts as in the other genera referred to this family. Inner 

 lamella of the second maxilla furnished with two plumose setae. 

 Mandibles with molar expansion obsolete, and replaced by a recurved 

 seta; cutting edge formed of three blunt teeth. Maxillipeds with 

 palp composed of three -articles, the last very narrow and elongate; 

 masticatory lobe short and truncate at tip. 



Terminal segment of abdomen triangular, with apex obtuse. 



Uropods of a structure similar to those in the other genera in the 

 family. 



The type of the genus is Pentoniscus pruinosus, new species. 

 This genus differs from all the known genera of Oniscidae in having 

 the flagellum of the second antennae composed of five articles. 



Proceedings U. S. National Museum, Vol. 44— No. 1954. 

 69077°— Proc.N.M.vol.44— 13 22 337 



