The Chonaphini 171 



and Thrinaphe hargeri Shelley (Shelley 1993c, d), and the extremely 

 flat species of Sigmocheir in the Sierra Nevada Mountains of California. 

 In contrast, although the eastern forms, representatives of the tribes 

 Apheloriini, Rhysodesmini, Nannariini, and Pachydesmini, differ in 

 the degree of convexity, they demonstrate similar overall body forms 

 without nearly the somatic differences of the western species. Adaptive 

 radiation of western xystodesmids has manifested itself in general 

 body form to a much greater degree than has that of the eastern 

 fauna. 



Genus Metaxycheir Buckett and Gardner 

 Metaxycheir Buckett and Gardner, 1969:67. Hoffman, 1979:157. Kevan, 

 1983:2968. 



Type species — Metaxycheir prolata Buckett and Gardner, 1969, 

 by original designation. 



Diagnosis — Paranota present and distinct on all segments; epiproct 

 without constriction; gonocoxae narrowly segregated by narrow sternal 

 band, latter with central lobe; telopodal elements not parallel, prefemoral 

 process arising near midlength of prefemur, acropodite arising distad; 

 prefemoral process narrowly blade-like, slightly bisinuate, without 

 projections; acropodite narrowly blade-like, in form of narrow, open 

 loop, curving through more than one vertical plane; cyphopod structure 

 unknown. 



Description — A genus of small to moderate-size chonaphine 

 xystodesminae with the following characteristics: 



Body composed of head and 20 segments in both sexes. Head of 

 normal appearance, smooth. Epicranial suture sharp, distinct. Antennae 

 moderately long, with 4 conical, terminal, sensory cones and microsensilla 

 on penultimate antennomeres. Facial setae with epicranial, interantennal, 

 frontal, genal, clypeal, and labral series; genal setae arranged among 

 3 groups. 



Terga smooth, polished; strictures broad, distinct. Collum large 

 and broad, ends terminating above those of succeeding tergite. Paranota 

 present on all tergites, broadest anteriorly, strongly declined, continuing 

 slope of dorsum and creating appearance of vaulted body. Peritremata 

 moderately distinct; ozopores opening sublaterad. 



Caudal segments normal for family. 



Sides of metazonites smooth, polished. Pregopnopodal sterna of 

 males with small lobes between anterior legs of 5th segment (4th 

 legs), moderate depression between 5th legs; 6th sternum strongly 

 depressed between both legs. Postgonopodal sterna flat, glabrous, and 



