ATOPETHOLID MILLIPEDS — HOFFMAN AND ORCUTT 155 



January 3, 1941, by Stanley and Dorothea Mulaik. 



Diagnosis: A mediiim-sized species of Arinolus, differing from the 

 preceeding species, with which it has been combined, in the shape of 

 the coUum, in having longer antennae, in the presence of a flared rim 

 on the front edge of the pleural lobe of the second segment, and in the 

 shape of the telopodite of the posterior gonopod, wliich likewise distin- 

 guishes it from all of the other species in which the male is known. 



Description: Based upon a male (USNM, Loomis coll.) from 

 Sacaton, Arizona, about 3.0 mm. in diameter, length undeterminable 

 due to extensive breakage. 



Front of head smooth and polished, without transverse wrinkles. 

 Clypeal foveolae 3-3. Antennae rather long and slender, reaching 

 back to the fourth segment, most of the articles more than twice as 

 long as broad. Lower edge of mandibular stipe with a well defined 

 marginal groove, the antennal depression smooth. Ocelli 28 on one 

 side and 27 on the other. 



Surface of coUum smooth and polished, the anterior marginal ridge 

 widest dorsally and becoming narrower toward the ends, the latter 

 evenly sub triangular and not produced somewhat caudoventrad. 



Pleural lobe of the second segment with a low but distinct raised 

 rim along the anterior margin. Body segments without punctation 

 or striation except on lower sides of the metazonites. The median 

 longitudinal dorsal suture is evident on most segments. 



The posterior gonopods (fig. \0,c,d) are of the typical Arinolus 

 form, but differ from those of A. torynophor in having a larger soleno- 

 merite and a more evenly oval terminal calyx. 



Distribution: This species was originally recorded from Quijotoa, 

 10 miles south of Ajo, and Congress Station, Arizona. In subse- 

 quently synonymizing Arinolus apachellus with the earlier name A. 

 torynophor, Loomis gave several additional localities that may apply 

 in part to this species, but we can be sure of only one. The male 

 upon which the preceeding account is based, from the San Tan Moun- 

 tains north of Sacaton, Pinal County, Arizona, provides the fourth 

 definitely known locality for apachellus. The range appears to coin- 

 cide with the plateau country of southwestern Ai'izona south of the 

 Gila River valley, and probably extends as far east as Tucson. It is 

 entirely probable that this species extends likewise into Mexico. 



Arinolus citrinus, new species 



Figure 11 



Holotype: Male (and male and female paratypes), USNM 2508, 

 from Bear Canyon, 6,000 ft., Mount Lemmon, Santa Catahna Moun- 

 tains, Pima County, Arizona, collected March 19, 1953, by Henry 

 and Alice Dietrich. 



