A new genus of Tantulocarida, Stygotantulus, is described based on material from an anchialine pool on Lanzarote, Canary Islands. It is the most primitive tantulocarid known and is ectoparasitic on representatives of at least two families of harpacticoid copepods. It is distinguished by the presence of 7 abdominal somites in the tantulus larva. The musculature of the penis on trunk somite 7 of the male suggests that it is derived by modification of the seventh thoracopods. The importance of trunk somite numbers in maxillopodan systematics is reexamined and an attempt is made to apply the concept of homology to the developmental processes determining somite numbers. The classification of the Crustacea, including the Tantulocarida, proposed by Starobogatov (1986), is criticized and the validity of the developmental-functional concept of the prototagma, as used by Starobogatov, is refuted. A new scheme of phylogenetic relationships among seven major maxillopodan groups is presented. |
