ECOLOGY OF 2 SYMPATRIC SPECIES OF NEUSTICURUS (SAURIA, GYMNOPHTHALMIDAE) IN THE WESTERN AMAZON OF BRAZIL

Neusticurus ecpleopus is linearly distributed along forest streams, us es stream banks and associated leaf litter, and numerically Feeds prim arily on ny larvae and ants. The most important prey items volumetrica lly are crickets and fly larvae. Neusticurus juruazensis occurs in lea f litter of damp low forest but is not directly associated with stream s. Fly larvae and collembolans are the most abundant items in the diet but orthopterans, centipedes, and fly larvae are the most important i tems based on volume, Activity patterns and body temperatures are simi lar between species, and temperatures of lizards and their microenviro nments are higher than average environmental temperatures based on com parisons with null temperature distributions. Morphologically, hi ecpl eopus is a more robust species with a relatively longer tail when comp ared with N. juruazensis. Sexual dimorphism in size and head proportio ns exists in N. juruazensis but not in N. ecpleopus, at least at our s tudy site. Associations between morphology and habitat use suggest tha t differences in habitat use explain relatively minor dietary differen ces and allow coexistence. A comparison of several species and populat ions of Neusticurus indicates that ecologically there is very Little v ariation among most species.