Episinus similanus is a species of Theridiidae spider endemic to New Zealand.

[1] This species was described in 1893 by Arthur Urquhart from male and female specimens.

[1] The female is recorded at 4mm in length whereas the male is 4.5mm.

[1] This species is only known from Waikato, New Zealand.

[1] Under the New Zealand Threat Classification System, this species is listed as "Data Deficient" with the qualifiers of "Data Poor: Size", "Data Poor: Trend" and "One Location".