Potential crypticity within two decapod (Crustacea) genera: Galathea (Fabricius, 1792) and Eualus (Thallwitz, 1891)

Sheena Conforti

Biomonitoring and correct species description are fundamental to understand health status of marine ecosystems. However, the use of a single identification tool for species distinction can lead to species misidentifications, having major consequences on ecological studies. Here, I used an integrative taxonomic approach to identify benthic decapods belonging to the genera Galathea (Fabricius, 1793) and Eualus (Thallwitz, 1891) collected in the Mediterranean Sea. 23 Galathea and 22 Eualus individuals were morphologically analyzed and sequenced at the mitochondrial COI gene to confirm their identity using BOLD Identification Engine. Morphological identification revealed the presence of two Galathea and three Eualus species, while species delimitation based on COI sequences of three Galathea and four Eualus species. DNA barcoding of COI revealed the potential presence of two still undescribed species: one cryptic to Galathea squamifera and one cryptic to Galathea intermedia. Contrasting results obtained by morphological identification and BOLD Identification Engine impeded the recognition of Eualus specimens and suggested misidentifications among BOLD reference records of Eualus cranchii, Eualus occultus and Eualus pusiolus. These results demonstrated that morphological identification overlooks cryptic species and that misidentifications often occur, highlighting the importance of using an integrative approach to increase the current taxonomic knowledge of benthic invertebrates.