Ordovician stromatoporoids from the langkawi islands, malaysia

Four species of labechiid stromatoporoids are described from Unit J of the Lower Setul Limestone (Middle Ordovician) of the Langkawi Islands. They include Labechia variabilis Yabe & Sugiyama 1930 and Rosenella woyuensis Ozaki 1938, reported previously from the Middle Ordovician of north China and the Gisbornian-Eastonian of New South Wales. Tentative correlations employing nautiloids and conodonts suggest that the Malaysian and perhaps some of the north Chinese labechiid occurrences have a pre-Chazyan Whiterockian (Llanvirnian) age, that is, they are the oldest known Ordovician stromatoporoids, appearing prior to the previously earliest known Chazyan forms of North America and Tasmania.