Upper Ordovician Bryozoa from Sardinia.

This paper presents the taxonomical descriptions of Upper Caradocian to Ashgillian bryozoans recovered from different localities from SW Sardinia and from one locality (Mulargia lake) from SE Sardinia. The investigated fauna belongs to 4 bryozoan orders: the Trepostomata, the Cystoporata, the Cryptostomata and the extant order Tubuliporata. These orders are represented by 39 species belonging to 28 genera. Twenty species and one cryptostome genus (Stereodictya) are new. The Trepostomata are the main constituents of the fauna; nevertheless in some localities (Mulargia lake, Portixeddu cove) the Cryptostomata become prevalent. The following new trepostome species are described: Batostoma phragmorarum, Bythopora crenulata, Dekayia minima, Dianulites cupuliformis, Diplotrypa sardoa, Eridotrypa constans, Eridotrypa obliqua, Hallopora cystoidalis, Hemiphragma curvilineum, Hemiphragma subtile, Panderpora gemmata, Panderpora moniliformis and Stigmatella sinuosa. The following new cystoporate species are described: Ceramoporella discoidalis, Crassaluna cystata and Papillalunaria magnum. The following new cryptostome species are described: Graptodictya vinassae, Nematopora hispida, Stereodictya crassum and Ulricostylus radiatus. Sardinian fauna shows similarities with both fauna of the Carnic Alps and southern France (Montaigne Noire), but this comparison needs further study. In SW Sardinia, the lithostratigraphic unit c (Upper Caradoc-Lower Ashgill) is dominated, in order of abundance, by Hallopora elegantula, Chasmatopora corniculata, Graptodictya meneghinii, Anaphragma meneghinii, Ceramopora discoidalis, Anaphragma regulare and Trematopora sardoa. Whereas in SE Sardinia the same unit is dominated by Chasmatopora corniculata, Graptodictya meneghinii, Hallopora elegantula, Ulricostylus radiatus and Dekayia minima. An important environmental change is shown by the bryozoan fauna, at the base of the unit e (Middle Ashgill), because of the dominance of large dome-like zoaria, belonging to Papillalunaria magnum, Prasopora fistuliporoides, Diplotrypa sardoa and Dianulites cupuliformis; abundant but subordinate are encrusting forms as Ceramophylla sp. and ramose bryozoans Nematopora hispida and Hallopora elegantula.