Latest permian radiolarian fauna from Klaeng, eastern Thailand

A latest Permian radiolarian fauna is described from a chert-clastic sequen ce exposed at Khao Wang Chik, Klaeng, eastern Thailand. This fauna was reco vered from a continuous siliceous sequence comprised of white to light gray siliceous shale, dark gray bedded chert, and dark gray siliceous shale. Th e fauna is composed of Neoalbaillella optima, Albaillella levis, A. triangu laris, Entactinia itsukaichiensis, Triaenosphaera minuta, Ishigaum trifusti s, Nazarovella inflata, Triplanospongos musashiensis, Copicyntra akikawaens is and others. These radiolarians represent the latest Permian Neoalbaillel la optima Assemblage reported from Japan, Russian Far East, Philippines, so uth and southwestern China, and northern Thailand. The radiolarian-bearing sequence was probably deposited in the deep, pelagic environment of the Pal eotethys Ocean. An overlying coarse-grained elastic sequence reflects an ab rupt change in local depositional environment, possibly caused by the narro wing of the Paleotethys Ocean in Early Triassic time. Twenty-eight radiolar ian species belonging to 15 genera are systematically investigated. One new genus, Klaengspongus, and four new species, Triaenosphaera longispina, Ish igaum klaengensis, Pseudospongoprunum? fontainei, and Klaengspongus spinosu s are described.