The sub-cylindrical to elliptical cortical shell is about 170 μm long and bears spines on each pole. The inner whorls of the shell are connected only loosely to the cortical shell and frequently are broken free of it, so the central disc can change its position and can be found near a pole. The outer wall is pierced by small- to medium- sized, irregularly arranged pores, which often lack frames. The inner whorls may be single or double, in some specimens the outer (cortical) whorls include incomplete polar caps. A well-developed pylome is present in most specimens.

Occurrence. Early–Mid Miocene, questionable occurrences in Late Miocene.

Remarks. L. p. amplissima is very close to L. p. polyacantha and transitional specimens can be found. It can be distinguished from L. p. polyacantha by the more quadrate, less regular shape of the shell and more evolute whorls.