142 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ni 



Genus Onychelus Cook 



Onychelus Cook, 1904, p. 67. 



Gosichelus Chamberlin, 1949, p. 168 (type species: Onychelus medolus Chamberlin, 

 by original designation). 



Type species: Onychelus obustus Cook, by original designation and 

 monotypy. 



Diagnosis: A group of small atopetholids characterized by the 

 opening of the ozopores in the mesozonites ; the extensive develop- 

 ment of lateral macrosetae on the legs; the production of the anterior 

 gonopod sternite into a median sub triangular projection nearly as 

 long as the coxal apices; and the posterior gonopod having the coxal 

 and telopodital elements distinct and separate but connected by a 

 flexible articulation, the telopodite being slender, falciform, and dis- 

 tally notched or bifid in all the known forms. 



Discussion: The original diagnosis of this genus and its only in- 

 cluded species was fairly detailed with respect to body form but vir- 

 tually ignored the genitalia and provided no drawings of those struc- 

 tures. This neglect gave rise to a considerable volume of confusion, 

 most of which has been outlined in the discussion of Atopetholus on 

 page 134. When the type series of 0. obustus was finally discovered 

 and studied in 1949, it was found that Cook's reference to the form 

 of the posterior gonopods was badly in error, and had misled Cham- 

 berlin into using the name Onychelus for a group of species that we 

 have referred to Atopetholus. For several small Sonoran species that 

 he had previouslj^ named in Onychelus, Chamberlin recentlj^ provided 

 the name Gosichelus. But since the tjY>e of that generic name, medolus 

 Chamberlin, has been found to be congeneric with obustus, we herewith 

 establish the synonymy of the two, and hope that with the publica- 

 tion of the accompanjdng drawing the case of the enigmatic Onychelus 

 has been brought to a close. 



Onychelus obustus Cook 



Figure 8 

 Onychelus obustus Cook, 1904, p. 68.— Chamberlin and Hoffman, 1958, p. 157. 



Holotype: Male (and numerous paratypes), USNM 797, from the 

 Colorado Desert, Riverside County, California, collected by C. R. 

 Orcutt. 



Diagnosis: Differing from 0. jaegeri and 0. medolus b}^ slight 

 qualitative differences in the form of the male gonopods that may or 

 may not be worthy of specific recognition. No tangible separation 

 of these three entities can be made without reference to illustrations. 



Description: From the original generic description the following 

 is taken: 



