REVISION OF BORARIA AND GYALOSTETHTJS — HOFFMAN 313 



body structure may vary considerably among species. This condition 

 is particularly true in Rhysodesmus itself, the species of which share 

 an essentially identical gonopod pattern. In Boraria the telopodite 

 is simple and distally laminate, with a slender, acicular prefemoral 

 process. In B. media and B. deturkiana the gonopod is similar in 

 most respects (cf. figs. 10, 18), distally the telopodite is accuminate. 

 In B. stricta the corresponding region is hastate with a distal and two 

 subterminal acute projections, but, with low magnification, the 

 gonopods of all three species are nearly identical. The gonopod of 

 Gyalostethus monticolens is somewhat different in structm-e. There is 

 a much shorter prefemoral process, the glabrous part of the telopodite 

 is much less laminate than in B. stricta, and the distal extremity is 

 expanded and laciniate when examined with sufficient magnification. 

 In this character alone G. monticolens is as different from the three 

 species of Boraria as the latter are from Mexican Rhysodesmus. In 

 association with the many other structural pecularities of G. monti- 

 colens, this difference leaves no doubt that the species is not congeneric 

 with B. stricta and, in fact, is probably not even closely related to it. 



Within the limits of the species here considered, the gonopods are 

 virtually identical. The prefemoral process in Gyalostethus monti- 

 colens varies a little in length but only as sporadic individual variation. 

 In Boraria media there is a slight variant in the shape of the telopodite 

 just below the prefemoral process (cf. figs. 9, 10), and the two gonopod 

 forms that are so characterized do occur in vicarious populations. 

 Some authors would instantly accord specific status to these popula- 

 tions, but I think that, at the present, a conservative treatment is 

 desirable (see the discussion under "Variation" in the account of 

 B. media). 



Cyphopods. — The transverse sympleurite of the third segment in 

 female xystodesmids is modified rarely into any special kind of epigynal 

 structure although there may be enlarged lateral lobes of the anterior 

 edge as in Pachydesmus and some other genera. The sternum and legs 

 of the second pair likewise tend to be quite uniform, but as a rule the 

 cyphopods themselves may be different from one species to another 

 and sometimes even differ among subspecies (cf. my Pachydesmus 

 paper, 1958, figs. 5a-f). One highly variable cyphopodal element is 

 the basal receptacle, which may be a semiglobose or semicircular 

 shielding structure that extends on both sides of the valves. In 

 others the receptacle is reduced to a flat, simple plate just large enough 

 for muscle attachment; in a few, such as Cherokia, the receptacle is 

 not present. In both of the genera treated here, it is reduced in size 

 but not otherwise differing between the two groups. In Boraria 



