Trididemnum maragogi sp. novo (Ascidiacea, Didemnidae) trom Alagoas, Northeastern Brazil

The new species of didemnid ascidian, Trididemnum maragogi sp. nov., is described from the Northeastern Brazilian coast. Many small colonies aggregate on calcareous algae. They are brown and more or less covered by spicules, depending on exposure to the sun, which suggests the presence of symbiotic algae. This species is characterized by a non pigmented zooid with a very long oral siphon bordered by six finger-like lobes, a branchial sac with anterior and posterior non perforated areas, a short muscular process on the esophageal peduncle and a testis with one large follicle partially surrounded by 6-7 coils of the sperm duct