| Singular | Plural | |
|---|---|---|
| Nominativ | pentacontarchus | pentacontarchi |
| Genitiv | pentacontarchi | pentacontarchorum, pentacontarchum |
| Dativ | pentacontarcho | pentacontarchis |
| Akkusativ | pentacontarchom, pentacontarchum | pentacontarchos |
| Ablativ | pentacontarcho | pentacontarchis |
| Vokativ | pentacontarche | pentacontarchi |