Shell average for the genus, thin shelled with 5 Vi whorls, triangular in shape. The protoconch is small, smooth and almost in the same plane as the first whorl. On this first whorl starts a sculpture of raised axial ribs crossed by one spiral rib. This spiral rib develops in 5 spiral ribs as the shell grows. Both the axial and spiral ribs are thin, solid and raised. The sculpture is deep and on the later whorls the upper spiral rib is almost in the same plane as the suture, forming a neat shoulder. On the later whorls the axials are slightly sinuous in shape. The two lower spiral ribs form the keel, the lower one extending a little over the second last one. There are 41 axials on the last whorl. The base is convex, with 10 spiral ribs. The interspace of the two first spiral ribs is smooth, between the second and the third appears an axial sculpture that becomes more pronounced towards the umbilicus. Between 6 and 7, we have already a square sculpture between the raised axial and spiral ribs. On the inside of the umbilicus there are 18 small knobs against the 10lh spiral rib that forms the umbilical keel. Behind each knob there is an axial rib inside the umbilicus. Aperture with one knob on the base and two knobs on the inside of the outer lip, the lower one hardly visible. Nacreous inside. Overall color of the shell white, slightly translucent.

Calliobasis magellani n. sp. differs
- from all other Calliobasis by the presence of the long axial ribs inside the umbilicus.
- Calliobasis lapulapui n. sp. By the regular sculpture of the more convex base.
- Calliobasis spectrum Marshall, 1991 Has a much smaller shell with a much smaller first whorl, a less sinuous shape of the axials and a smaller shoulder on the whorls.

TYPE LOCALITY
The Philippines, Bohol Sea. 8°56.1'N.-123016.6'E.
DISTRIBUTION AND HABITAT
Dredged between 318 and 322 m deep. Only known from the type locality.