Placocista sinuospina Chardez, 1966

Diagnosis: Shell regular and oval, with both broad faces forming a sharp peripheral ridge that runs continuously around the shell up to the pseudostome. In elevation the general outline resembles P. spinosa, but the shell is less compressed. Test transparent and hyaline. Shell covering composed of regular, well‑imbricated oval plates, fused by marginal overlap. Toward the posterior end, long sinuous spines arise between the plates, directed backwards; their number varies and this feature represents the principal diagnostic character of the species. Pseudostome narrow and linear, bordered by small, smooth chitinous lips. Only empty tests were observed in the type material.

Dimensions: Chardez, 1966: Length 100–120 µm (No width or thickness given in the original description.)

Ecology: In Sphagnum, collected in a Sphagnum pool at Oneux–Theux (Belgium).

Distribution: Belgium — Oneux–Theux (type locality)