Unusual median pores of Alona head shields recovered from recent and pre-industrial sediments of Alpine lakes

We report the finding of Alona (affinis-quadrangularis) - type headshields with atypical median pores, recovered from the sediments of high-mountain lakes. Subfossil Cladocera remains were analyzed in the framework of the European Project EMERGE (2000- 2002, European Mountain lakes Ecosystem: Regionalisation, diaGnostic & socioeconomic Evaluation), to evaluate changes in their assemblages consequent to industrial pollution. Observed response includes an increase in A. affinis with respect to A. quadrangularis after industrialization. According to the literature, the atypical head shields are most probably attributable to A. affinis. However, being detected in high mountain lakes, these remains may be interpreted as a result of mutations, as the intensity of UV radiation is high in these environments. In this sense, they might be interpreted as the abnormal Daphnia’s and Chydorus’ ephippia, which were also detected in the sediments of these lakes.