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<br />moumJJn'sucker ITig.., I ~ ,lnd IH) co-occutrtng with
<br />trouts, ,lnd C:lhlta ..u(kt'r"'m,l/,JIIi(~ (dl'lf.l {Fig. .Bl
<br />card\" t,lken .It Ck\":itlOn!. lower than 900 m. In
<br />cont~ast. the Or.ltJ. sucker''''/,JtJ/tJlt Op"r.l (Flf, +11
<br />lives ~eneraJh. hehl'l'l 900 m In W;Hm. shallow. sJnd.
<br />oocwm desert srrt'ams of the RIO Sonora ImmeJlolrely
<br />west llf thl' RIO YaljUl b.lS11l :\"U[hJn~ IS kmlV.-n pf
<br />the food or spJ.Wnln~ lubns of ,InY uf the laSt fl.ur
<br />speCIes.
<br />As WIth the suckers. [h(. ecoklfies of .\feXI(all
<br />chubs dte ren1J.rbbly little- known despite theIr
<br />Widespread dmrlbutions anJ Jbund.lnn.. The Riu
<br />Y.lqul supp\>rts four kmds. rounduil (hub-',-ba,..,/uo
<br />.llu.J rf.l','lJ./. )",lqUl chub,-d"r.Jlir" L.lqfil. Dc-st-r[
<br />chub/rL,r.lllt,! .Ill .IeJl.rt,-,. .1Od ,on unJescnhed
<br />specIes. the Ilrst I)f wnll.:h IS ..h,lted vd[h [he
<br />
<br />FIgure 43. Cahlta sucker/mata/ate
<br />canlfa. 16.0 em In total length,
<br />lrom the RIO PaplgochlC.
<br />Chihuahua little is known 01 this
<br />species of stream..<fwelling sucker,
<br />which was nOl described until the
<br />1980s. II IS conSidered threalened,
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<br />Figure 44 Opafa suckerlmatalofe
<br />Opara. 15.0 em 10 tOlallength,
<br />'rom "MIller's Canyon."
<br />headwaters 01 the RIO Sonora.
<br />Sonora II remams locally
<br />common, bul the RIO Sonora IS
<br />rapidly being developed for water
<br />supply and the fish is considered
<br />01 special concern,
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<br />Colorado s)"stem_ Gila chur,lcJ.,...r,,/if!.l dtl Gild is found
<br />only In the lower Color.too r,..SIn. anJ ,lnother
<br />speCIes. the SOnllran chubld'"r.l/I/(, IIJ1!Ijrf11Jr, is
<br />restrJctt'd w tht. small Rio CI)nCepClI)n hHin. ,I smalJ
<br />drainage sandWIChed With [ht' Rio Sonora bt'twt'en
<br />the YaquI and Colorado sYS[t'm..,
<br />RounJtall chuhs (Fi~. 4')) are hi~hly vJrJable In
<br />SIZe:. WIth some PllPula[ions Mhlt>nn,e onl~. 15 Cffi as
<br />.Idults ,lnJ others rJngln,f: m almost 65 cm The
<br />specil:s inhabItS pools and I:ddleS hdow nmes. ,\OJ
<br />often occupies qUiet waters beneath cut banks or
<br />near boulders adlJCent to swdter currents. Roundud
<br />are \'arlJ.r.le In food habits, SOffit'tlmeS feedln,e 011
<br />al,e.lt" JnJ lHhet tlmes bt'comlng plSCJVOrous or even
<br />eJting t("tresena] J.mm,lls such as lizards thJ.t fall into
<br />[he w,Her They brt"ed In spring and eulr summer In
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