Type Species of Tibiaporrhais is ?Nudivagus cooperensis Stephenson, 1941.
Original Description by Elder, 1990:
- "Shell large for family (8 to 10 cm in length); turriculate, having 8 to 11 whorls and spire angle of 20 to 30 degrees. Whorl sides broadly convex anteriorly and slightly constricted posteriorly below a distinct, but closely appressed suture. Surface ornament weak; consisting of numerous crowded, narrow spiral striae and fine, sinuous axial growth lines. Aperture moderately elongate and trapezoidal. Outer lip slightly flaring with two discrete spine.like processes originating from two indistinct carinae that extend for less than one-third of body whorl; posterior process projects in slightly posterior direction, anterior process projects in horizontal to slightly anterior direction. Anterior canal broken on all specimens, but suggestive of moderate length. Inner lip slightly callused. Lacks evidence of posterior canal or callus extending upwards onto spire."
Tibiaporrhais species are:
might belong to Tibiaporrhais