First record of the non-indigenous Myrianida pachycera (Augener, 1913) (Annelida: Syllidae) in the Mediterranean Sea revealed by integrative taxonomy

The non-indigenous syllid polychaete Myrianida pachycera (Augener, 1913), originally described from Australia, is reported for the first time in the Mediterranean Sea, based on individuals sampled in port environments in the Tyrrhenian and Ionian Sea. The identity of the specimens was investigated through morphological identification and DNA barcoding of two individuals, resulting in COI sequences with almost 100% identity with an individual from California. Myrianida pachycera must be considered non-indigenous for the Mediterranean Sea. The distribution of this species seems to be relatively wide in the basin, but its detection has possibly been hindered by the loss of the majority of the diagnostic characters following fixation. Conversely, due to their striking live colour pattern, live individuals might be successfully tracked via citizen science.