Monitoring and updating the geographic spread of non-native species is of chief importance for conservation. Here we report on the range expansion of the Red Sea alien heterobranch gastropod Lamprohaminoea ovalis in southeast Spain, which reached the Alboran Sea (coast of the Granada province) in autumn 2023. This record represents the westernmost of the species in the Mediterranean Sea. The species is established in the studied area with a seasonal presence. It appears in summer, reaches reaches population peak in autumn, and disappears during winter. The importance of “citizen scientists” for information about the distribution of species and monitoring the status on invasive populations is stressed.