A new monotypic genus of cobweb spiders from the Russian Far East (Araneae, Theridiidae).

A new theridiid spider, Knoflachiakurilensis gen. et sp. nov. , is described from the Kuril Islands (Kunashir). The new genus belongs to the ' Anelosimus clade (clade 24)' of Agnarsson (2004). A pair of raised, fused setal sockets on the cheliceral promargin adjacent to the fang base was found to be another synapomorphy of all the 'distal theridiids' (the 'elongated central claw clade (clade 33)': argyrodins, ' Anelosimus clade' and theridiins). Knoflachiakurilensis sp. nov. demonstrates a male polymorphism similar to some Anelosimus Simon, 1891 species (e.g., A.studiosus (Hentz, 1850)).