AN EVALUATION OF THE SYSTEMATICS OF THE GENUS THALIA (THALIACEA, SALPIDAE) BASED ON NEW MATERIAL FROM THE EASTROPAC AND MORO EXPEDITIONS

Until 1973, when Van Soest revised Thalia Blumenbach, 1798, this genus comprised only two species: Thalia democratica (Forsskal, 1775) and T halia longicauda (Quoy & Gaimard, 1824). The former showed great varia bility, which led Van Soest to distinguish five species: T. democratic a, T. orientalis, T. rhomboides, T. cicar, and T. sibogae. Some author s have ignored this revision considering the observed differences of i nfraspecific level. In the present work new material is studied analys ing variables not previously considered, such as the development of bl astogenic stolons in the solitary zooids and the location of the tunne l opening through which the bud blocks are liberated. These characters previously permitted a separation of closely related species in the g enus Ihlea. The results show that stolen features, even though they pe rmit a separation of solitary zooids of Thalia longicauda, do not disc riminate all species of the ''T. democratica group'' since they are on ly useful in distinguishing T. democratica from T. sibogae. Other vari ables, mainly qualitative, do permit differentiation. The sympatric di stribution of these taxa supports Van Soest's hypothesis as well.