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The Middle Devonian Epoch, ~ 393–383 million years ago, is known for a peak in diversity and highest latitudinal distribution of coral and stromatoporoid reefs. About 388 million years ago, during the late Eifelian and earliest Givetian, climax conditions were interrupted by the polyphased Kačák Episode, a short-lived period of marine dys-/anoxia associated with climate warming that lasted less than 500 kyr. Reconstruction of the seawater temperature contributes to a better understanding of the climate conditions marine biota were exposed to during the event interval. To date, conodont apatite-based paleotemperatures across the Eifelian–Givetian boundary interval have been published from Belarus, France, Germany and North America (10–36° S paleolatitude). Here we provide new δ18Oapatite data from the Carnic Alps (Austria, Italy) and the Prague Synform (Czech Republic). For better approximation of the paleotemperature record across the Kačák Episode, a latitude-dependent correction for Middle Devonian seawater δ18O is applied. Because δ18Oapatite data from shallow marine sections are influenced by regional salinity variations, calculated mean sea surface temperatures (SST) are restricted to more open marine settings (22–34° S paleolatitude). Water temperatures reach ~ 34 °C in the Prague Synform and ~ 33 °C in the Carnic Alps and suggest that SSTs of the southern hemisphere low latitudes were ~ 6 °C higher than previously assumed for this time interval.

Four species of rugose corals (one new) are described from the Silurian of the Kurosegawa Terrane, Southwest Japan. They areNeobrachyelasma japonican. sp.,Pseudamplexussp.,Amsdenoidessp., andAmplexoidessp. aff.A. chaoi(Grabau, 1925). These species occur in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow in age.Neobrachyelasmais reported for the first time from Japan. This genus occurs in the Lower Llandovery to Upper Silurian of Japan, South China, Kazakhstan, and the Altai and might be distributed only in South China and Japan during the Late Llandovery. Its occurrence in Japan may support a paleogeographic proximity of ‘Proto-Japan’ and the South China Block during the Silurian.

Three rugose species of the family Holmophyllidae Wang, 1947 are described for the first time from the Gionyama Formation of the Kurosegawa Terrane, Southwest Japan. They are Holmophyllum sp., Holmophyllum? sp., and Labechiellata reguloris (Sugiyama, 1939). These species are found in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow (Silurian) in age. Holmophyllum and Labechiellata are typical cosmopolitan genera. The compound holmophyllids such as Labechiellata may indicate tropical environments and suggest that ‘Proto-Japan’ was, like other areas that yield these corals, located in subtropical to tropical latitudes during the Silurian.

Three rugose species in two genera—Nanshanophyllum hamadain. sp.,N. gokasensen. sp., andShensiphyllumsp.—are described for the first time from the Kurosegawa Terrane, Southwest Japan. These species occur in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow (Silurian) in age. The two genera,NanshanophyllumandShensiphyllum, formerly were known only from South China and Qaidam. The occurrence of these two genera in Japan may indicate a paleogeographic connection between ‘Proto-Japan’ and the South China Block during the Silurian.