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Morphologically and reproductively constrained colonial Rugosa were recovered from Late Carboniferous (possibly Bashkirian) strata of the Akiyoshi Terrane, south-west Japan. Individual corallites are very small (diameterc.1.7 mm) and exhibit a uniserial fasciculate form with a deep calice. The essential characteristics of the Rugosa, including walls, major and minor septa, tabulae and columellae, are present. However, each morphological component shows an end-member feature (e.g. thick walls for corallites with very small diameter and simple columella), especially consistent with rugose corals considering phylogenetic and structural constraints. Increase is parricidal, occurring only by dichotomous branching in the cardinal–counter plane. The combination of these components results in a somewhat unbalanced morphology, and is the basis for the establishment ofYamatophyllum ultimumgen. et sp. nov. It is likely that the new genus was a terminal lineage, an ephemeral evolutionary experiment within the rugosan clade. Interestingly, morphologically similar but phylogenetically distinct corals commonly appeared in the initial stages of both rugosan and scleractinian diversifications, suggesting restrictions on the available morphospace of corals throughout the Phanerozoic. http://zoobank.org/urn:lsid:zoobank.org:pub:F847EC54-28F3-405B-AC7A-459F60458FF0 [ABSTRACT FROM AUTHOR]

Dendrophyllid Scleractinia exhibit a variety of colonial morphologies, formed under the strict constraints on (1) budding sites, (2) orientations of the directive septa of offsets, (3) inclination of budding direction, and (4) those constraints in every generation. Dendrophyllia cribrosa exhibits a sympodial dendroid form, characteristically large coralla, and occasional fusions of adjacent branches within the same colony. Adjacent corallites are bound and supported by coenosteum skeleton. This study examined the inner skeletal structures at the junctions of fused branches using a non-destructive microfocus X-ray computed tomography (CT) imaging approach, and considered the reasons for the large colonial sizes and their adaptive significance. Three-dimensional reconstructions of two-dimensional X-ray CT images reveal that individual corallites are not directly connected in fused parts. Additionally, no completely buried individuals were found within fused skeleton. When adjacent branches approach one another, constituent corallites change their growth directions to avoid collisions between the branches. The adjacent branches fuse without a reduction in the number of constituent corallites, leading to the establishment of reticular and rigid colonial structures. In addition, a nearly even distribution of individuals on the colony surface facilitates efficient intake of nutrients. Thus, the growth of large D. cribrosa colonies involves avoidance of collision between constituent individuals, the reinforcement of colonial structure, and efficient uptake of nutrients. These observations provide insights on the dynamics of interrelationships between colony-making mechanisms and the adaptive strategies required under habitat conditions such as specific current activities., (Copyright © 2014 Elsevier Inc. All rights reserved.)