KEY TO THE CRAYFISH OF ASTACIDAE FOUND IN BULGARIA

1 ‒ Area behind cervical groove smooth, cervical spines absent (Fig. 1a), rostral borders triangle (Fig. 1b), chelae surface granulation very big (Fig. 1c), under side dirty white or reddish (Fig. 1d). ………………………………………………..…… Austropotamobius torrentium

‒ Area behind cervical groove with different number of spines (Fig. 2a; Fig. 3a), rostral borders parallel or almost parallel (Fig. 2b; Fig. 3b). ………………...….………………..………... 2

2 ‒ Numerous number of well visible spines present from behind cervical groove (Fig. 2a), fingers of chelae long and narrow, under side pale (Fig. 4a), abdominal pleura 2-4 tapering, with sub terminal spine(s) (Fig. 2c), talon on second gonopod present in male (Fig. 2d). ……………………………………………………...………….. Astacus leptodactylus

‒ Numbers of spines behind cervical groove smaller (Fig. 3a), chelae robust, wide, under side red to brown (Fig. 4b), abdominal pleura 2-4 broad and rounded (Fig. 3c), talon on second gonopod in male absent (Fig. 3d). …………………………….…....................... Astacus astacus