Articulation and growth of skeletal elements in balanid barnacles (Balanidae, Balanomorpha, Cirripedia)

The morphology and ultrastructure of the shells of two balanid species have been examined, paying special attention to the three types of boundaries between plates: (i) radii-parietes, (ii) alae-sheaths, and (iii) parietes-basal plate. At the carinal surfaces of the radii and at the rostral surfaces of the alae, there are series of crenulations with dendritic edges. The crenulations of the radius margins interlock with less prominent features of the opposing paries margins, whereas the surfaces of the longitudinal abutments opposing the ala margins are particularly smooth. The primary septa of the parietes also develop dendritic edges, which abut the internal surfaces of the primary tubes of the base plates. In all cases, there are chitino-proteinaceous organic membranes between the abutting structures. Our observations indicate that the very edges of the crenulations and the primary septa are permanently in contact with the organic membranes. We conclude that, when a new growth increment is going to be produced, the edges of both the crenulations and the primary septa pull the viscoelastic organic membranes locally, with the consequent formation of viscous fingers. For the abutting edges to grow, calcium carbonate must diffuse across the organic membranes, but it is not clear how growth of the organic membranes themselves is accomplished, in the absence of any cellular tissue.This research was funded by projects CGL2017-85118-P (A.G.C., C.S. and C.G.) and CGL2015-64683-P (A.B.R.N.) of the Spanish Ministerio de Economía, Industria y Competitividad, the Unidad Científica de Excelencia UCE-PP2016-05 of the University of Granada (A.G.C. and A.B.R.N.) and the Research Group RNM363 of the Junta de Andalucía (A.G.C.). N.A.L. acknowledges support from CONICYT-Chile through grant nos. FONDECYT 1140938, PCI REDES 170106 and PIA ANILLOS ACT172037, for international collaborative research with A.G.C. and A.B.R.N

The European Security Order between American Hegemony and French Independence

We investigate the impact of historically rooted domestic constructions of purpose and ambition on the patterns of discord and collaboration in the Franco-American relationship over the course of the postwar and post-cold war periods. We stress the importance and tenacity of domestic historical constructions for explaining and understanding the foreign policy strategies that would otherwise confound a power-based analysis. The Franco-American bilateral relationship, in particular, illustrates the persistence and tenacity of each nation's historically constructed foreign policy conception during the bipolar distribution of power during the cold war and the contested unipolarity of the post-cold war era. We conclude with an assessment of the salience and relevance of domestic elements of foreign policy role and purpose for explaining and understanding how their bilateral relationship has affected the European security order into the second decade of the twenty-first century

Biodiversity and Taxonomy of the Parasitic Crustacea

Crustaceans have independently adopted a parasitic mode of life on numerous occasions, and this chapter reviews the classification and species richness of each of the parasitic clades, which lie within two major pancrustacean lineages, the Multicrustacea and the Oligostraca. Tabulated data are presented on the genera, species richness and host usage of the whale lice (Cyamidae); the generic and species richness of the families of hyperiidean amphipods; the generic and species richness and the host usage of the families and subfamilies of epicaridean isopods; the species richness, salinity regime and host taxon of cymothoid isopods; the generic and species richness and the host usage of the families of Ascothoracida and Rhizocephala; the species of Tantulocarida and their hosts; the generic and species richness and the host usage of the families and family-level groupings of cyclopoid and siphonostomatoid copepods; the species richness and salinity regimes of the genera of Branchiura; and the species richness and host usage of the genera of tongue worms (Pentastomida). Parasitic crustaceans use a total of 15 different phyla as hosts