1 5 – 2 0 , ▁are ▁considered ▁ad ul th ood . ▁ ▁Us es ▁Hy ale lla ▁az te ca ▁is ▁used ▁in ▁various ▁aqu atic ▁bio ass ays . ▁Because ▁of ▁their ▁wide ▁distribution , ▁ease ▁of ▁capt ive ▁reprodu ction , ▁and ▁its ▁n iche ▁in ▁lake ▁sed iments , ▁Hy ale lla ▁az te ca ▁is ▁used ▁in ▁aqu atic ▁to xic ology ▁ass ays ▁in ▁sed iments ▁ ▁Tax onom ic ▁history ▁ ▁Hy ale lla ▁az te ca ▁was ▁first ▁described ▁by ▁Henri ▁Louis ▁Fr éd éric ▁de ▁S auss ure ▁in ▁ 1 8 5 8 , ▁under ▁the ▁name ▁Am ph ito e ▁az te cus , ▁based ▁on ▁material ▁collected ▁by ▁Az te cs ▁from ▁a ▁" cis tern " ▁near ▁Ver ac ru z , ▁Mexico . ▁It ▁has ▁also ▁been ▁described ▁under ▁several ▁junior ▁syn onym s , ▁including : ▁Hy ale lla ▁dent ata ▁S . ▁I . ▁Smith , ▁ 1 8 7 4 ▁Hy ale lla ▁fl uv ial is ▁Lock ington , ▁ 1 8 7 7 ▁Hy ale lla ▁in erm is ▁S . ▁I . ▁Smith , ▁ 1 8 7 5 ▁Hy ale lla ▁kn icker bo cker i ▁B ate , ▁ 1 8 6 2 ▁Hy ale lla ▁orn ata ▁Pear se , ▁ 1 9 1 1 ▁When ▁Sid ney ▁Ir ving ▁Smith ▁ere cted ▁the ▁genus ▁Hy ale lla ▁in ▁ 1 8 7 4 , ▁H . ▁az te