A Sydney scientist has discovered seven new species of the tiny Australian peacock spider - a spectacularly coloured arachnid that dances to attract a female mate.

Jurgen Otto, with the help of colleague David Knowles, made the two latest discoveries of the creatures while looking for other spiders in Western Australia in November and had all seven named in the scientific journal Peckhamia last month.

"They are very, very colorful. They often have iridescent scales and they do something quite remarkable - they perform a courtship dance for females, to impress them," Otto said.