Upper Ordovician brachiopods from the Anderken Formation, Kazakhstan: their ecology and systematics

The brachiopod fauna from the Anderken Formation (Lower to Middle Caradoc) of the Chu-Ili Range, south-eastern Kazakhstan, is revised and described systematically. It consists of 62 species in 55 genera, of which the genera Tesikella, Olgambonites and Zhilgyzambonites (all Plectambonitoidea) and Ilistrophina (Camarelloidea) are new, and the species Bellimurina (Bellimurina) sarytumensis, Teratelasmella chugaevae, Foliomena prisca, Acculina kulanketpesica, Dulankarella larga, Kajnaria rugosa, Anoptambonites convexus, Olgambonites insolita, Zhilgyzambonites extenuata, Gacella institata, Placotriplesia spissa, Grammoplecia wrighti, Dolerorthis pristina, Austinella sarybulakensis, Plectorthis? burultasica, Bowanorthis? devexa, Pionodema opima, Parastrophina iliana, Ilistrophina tesikensis, Liostrophia pravula, Plectosyntrophia unicostata, Rhynchotrema akchokense and Nikolaispira guttula are new. Six brachiopod-dominated assemblages are recognised and defined, termed the Ectenoglossa, Tesikella, Mabella–Sowerbyella, Acculina–Dulankarella, Parastrophina–Kellerella and Zhilgyzambonites–Foliomena Associations. The relationships with contemporary faunas are assessed, and the Anderken brachiopods appear to have much in common with those of north-west China.