Nicodamids are small to medium-sized spiders with vivid red-and-black colours, often an entirely red cephalothorax and a black or two-coloured black and red abdomen. They are known only from Australia (including Tasmania) and Papua New Guinea. They have eight eyes in two straight rows and long, slender legs which may feature black sections. They build fairly sturdy sheet webs at ground level.
Before 1995 when Mark Harvey reviewed the family, Nicodamidae was thought to contain only a small number of species. Now there are many.
Nicodamus peregrinus is widespread, from the Nullarbor to the east coast as far north as Mackay, Queensland. Nicodamus mainae is found in south-western Australia. Durodamus only occurs in parts of eastern Australia where the average annual rainfall is less than 500 mm.
Ambicodamus has 11 species in areas with an average annual rainfall over 500 mm. Ambicodamus kochi and Ambicodamus marae are from Western Australia. Nine other Ambicodamus species are found in eastern Australia.
Litodamus is known only from Tasmania. Novodamus is found in Tasmania, Victoria and New South Wales.
Oncodamus occurs east of the Great Dividing Range, Oncodamus bidens in southern New South Wales, and Oncodamus decipiens more northerly. Nicodamids range from 3 to 12 mm in body length.