CONCLUSION
In conclusion, our study demonstrates that the threatened and geographically restricted freshwater sand goby, Orsinigobius croaticus , produces pulsatile sounds during intersexual laboratory experiments. These sounds were produced during courtship, pre-spawning and spawning phases of the reproduction interactions with females. In addition, our results suggest that levator pectoralis muscles could be responsible for pulse emission. Finally, at the interspecific level, acoustic signals produced by soniferous sand gobies appear to be sufficiently different and species-specific to enable the discrimination of species.