This species is known to me only from Thiele's figure and brief description. The type, only 13 mm. in height, is almost certainly an immature shell; it does however, appear to closely resemble the subspecies palawanica, a much larger shell, described following. Apart from the very considerable size difference between aequatorialis and palawanica, the latter has many more of the spire-whorls bearing peripheral tubercles, after which the carina continues as a smooth peripheral ridge over the otherwise smooth body-whorl. In aequatorialis the plain last whorl is globose and does not have a peripheral carina. The Indonesian undosa, which appears to be closely allied also, has the smooth body-whorl similarly ridge margined at the periphery but this whorl is much less inflated than in either aequatorialis or palawanica.

East Africa, off Somali Coast in 1644 metres.