Caprellidae (Crustacea: Amphipoda) from the Great Barrier Reef and Adjacent Localities Guerra-García, J. M. Records of the Australian Museum 2006 58 417 458 7PNLV Guerra-García, 2006 Guerra-García 2006 [307,483,779,803] Malacostraca Caprellidae Mayericaprella Animalia Amphipoda 11 428 Arthropoda genus gen. nov.   Diagnosis. Flagellum of antenna 2 2-articulate. Gills present on pereonites 2–4. Pereopods 3 and 4 absent. Pereopod 5 four-articulate. Pereopods 6 and 7 six-articulate; propodus with two pairs of proximal grasping spines. Mandibular palp 3-articulate. Molar absent. Abdomen with two pairs of 2- articulate appendages.   Etymology.  Mayericaprellais derived from “Mayer” and “  Caprella” to dedicate the genus to P. Mayer for his valuable contributions to the knowledge of the Caprellidaeduring the last century. Gender: feminine.    Typespecies.  Mayericaprella arimotoi n.sp.   Remarks.  Mayericaprella n.gen.is close to  Caprellina, especially to  Caprellina bispinosaMüller, 1990. The general shape of the body, the structure of the antennae, the distribution of the gills, the mouthparts (especially the maxilliped) and the abdomen are similar to that of species of  Caprellina. However, the gnathopods and pereopods are different, especially pereopod 5 which is four-articulate in the new genus and 2- or 3-articulate in  Caprellina(2- articulate in  C. bispinosaand 3-articulate in  C. longicollisand  C. spiniger). The only other genus in the subfamily Phtisicinaewith four-articulate pereopods 5 is  Quadrisegmentum. Although  Mayericaprellashares with  Quadrisegmentumthe presence of four-articulate pereopod 5, the genera differ chiefly in pereopods 3 and 4, being present in the latter and absent in former. The number of articles on pereopod 5 is an important phylogenetic character in the Phtisicinaebecause they show progressive changes in segmentation of the limb (Hirayama, 1988). At present, the number of articles in the pereopods distinguishes genera (Mayer, 1903; Arimoto, 1976). For instance, genera close to  Caprellina, such as  Hircella, have been erected mainly on the basis of one-articulate pereopod 5. Nevertheless, Müller (1990) assigned  C. bispinosa(having a 2-articulate pereopod 5) to  Caprellina(characterized by a 3-articulate pereopod 5) instead of erecting a new genus for the species. Further study might show that  C. bispinosashould be transferred to a different genus. The general morphology of  Mayericaprella, with a four-articulate pereopod 5, is closer to  Caprellina bispinosawith pereopod 5 2-articulate, than to the remaining species of  Caprellinawith a 3- articulate pereopod 5. Actually, the phylogenetic relationships among the species of the seemingly closely related genera  Caprellina, Pseudocaprellina, Hircellaand  Liriarchusrequire study. The continuous gradient of variation in the characters of species of these genera makes generic distinctions difficult. A complete phylogenetic revision of the Caprellidae, necessary to address properly future taxonomic studies of this group, is required.