Pigmentation disorders in three specimens of spiny dogfish, Squalus acanthias Linnaeus, 1758, from the Gulf of Venice, northern Adriatic Sea

This study reports three cases of pigmentation disorders in Squalus acanthias from the Gulf of Venice. Two specimens exhibited spotless phenotypes, whereas one exhibited hypermelanism. Morphological assessments were conducted for two individuals, alongside genetic analysis of mitochondrial genes to determine phylogeographic relationships. Both specimens belonged to the South Pacific/Atlantic/Mediterranean haplogroup, with the first one associated with the main haplotype and the second one linked to a rarer haplotype. This study emphasizes the need for proper identification based on morphology and genetics when pigment disorders hinder a clear-cut species assignment.