Abstract
A new theridiid spider, Knoflachiakurilensisgen. 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). Knoflachiakurilensissp. nov. demonstrates a male polymorphism similar to some Anelosimus Simon, 1891 species (e.g., A.studiosus (Hentz, 1850)).