Ariamnes triangulatus is a species of tangle web spider endemic to New Zealand.
This species was described in 1887 by Arthur Urquhart from male and female specimens.
This species is only known from Te Karaka, New Zealand.
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".