Apseudopsis latreillii is a common tanaidacean species widely-distributed in the north-east Atlantic, but its diagnostic characters remain unspecified. Furthermore, intraspecific variation in relation to its developmental stages has not been described.

Apseudes latreillei (Milne-Edwards) is a common and abundant tanaid in soft-bottom communities from waters off East Atlantic and Mediterranean coasts. Its sensitivity to pollution is not clear despite being an abundant and widely distributed crustacean,

Apseudopsis latreillii is a common tanaidacean species widely-distributed in the north-east Atlantic, but its diagnostic characters remain unspecified. Furthermore, intraspecific variation in relation to its developmental stages has not been described.

Tanaidacea and Cumacea are crucial for understanding the phylogenetic relationships of “core group” peracarids. Here, the haemolymph vascular system in three tanaidacean and four cumacean species was studied on the basis of histological sections and 3D