iar ski , ▁T . ▁tar oba , ▁T . ▁trig utt atus ▁and ▁T . ▁z on atus . ▁T . ▁ag u ar ague , ▁T . ▁alter us , ▁T . ▁bel ensis , ▁T . ▁bo yle i ▁and ▁T . ▁ram os us ▁also ▁form ▁a ▁diagn os able ▁species ▁assemb lage . ▁ ▁Distribution ▁and ▁habitat ▁Species ▁of ▁Tr ich omy ct er us ▁inhab it ▁a ▁divers ity ▁of ▁habit ats ▁throughout ▁South ▁and ▁Central ▁America ▁from ▁Costa ▁Rica ▁in ▁the ▁north ▁to ▁Pat ag onia ▁in ▁the ▁south ▁and ▁from ▁low land ▁Atlantic ▁rain for est ▁in ▁the ▁east ▁to ▁And e an ▁high land ▁streams ▁in ▁the ▁west . ▁They ▁are , ▁together ▁with ▁Ast ro ble pus ▁and ▁Or est ias , ▁among ▁the ▁very ▁few ▁native ▁fish ▁gener a ▁at ▁high ▁alt itude ▁in ▁the ▁And es ▁and ▁in ▁some ▁places , ▁for ▁example ▁certain ▁high - e lev ation ▁local ities ▁in ▁western ▁Argentina , ▁Tr ich omy ct er us ▁are ▁the ▁only ▁fish es . ▁About ▁ 6 0 ▁nom inal ▁species ▁are ▁en demic ▁to ▁the ▁river ▁bas ins ▁dra ining ▁the ▁And es ▁and ▁hills ▁of ▁the ▁Gu ian an ▁Sh ield ▁and ▁about ▁ 3 0 ▁species ▁are ▁en demic ▁to ▁river ▁bas ins ▁dra ining ▁the ▁Brazil ian ▁Sh ield . ▁ ▁Despite ▁the ▁broad ▁distribution ▁of ▁the ▁genus , ▁most ▁species ▁have ▁limited ▁distributions ▁and ▁usually ▁are ▁restricted ▁to ▁only ▁one ▁river . ▁W