Key to larvae and adults of Greek brook lampreys of the genus Eudontomyzon

1 Horseshoe-shaped oral hood with oral cirri inside (larva) ........................................................................................... 2

— Oral disc with fimbriae and papillae at its periphery and teeth inside (adult) ............................................................. 3

2 Upper lip pigmentation <25% coverage; tongue precursor bulb and both sides of elastic ridge unpigmented; trunk length 46.8–50.8% TL; tail length 29.4–31.7% TL .................................................................. Eudontomyzon graecus

— Upper lip pigmentation ≥ 25% coverage; tongue precursor bulb and both sides of elastic ridge pigmented; trunk length 48.2–55.4% TL; tail length 21.2–30.6% TL .............................................................. Eudontomyzon hellenicus

3 First anterial row with one or more bicuspid teeth; first posterial row with two or more bicuspid teeth; tail length 29.3–33.0% TL ......................................................................................................................... Eudontomyzon graecus

— First anterial row teeth all unicuspid; first posterial row teeth all unicuspid or with a single bicuspid tooth; tail length 26.2–30.4% TL ..................................................................................................................... Eudontomyzon hellenicus