TABLE 1. Distribution and main characters of Leptochiton lignatilis n. sp., L. alveolus (M. Sars in Lovén, 1846) and L. belknapi Dall, 1878 , allowing comparisons.
| Distribution/taxonomic characters | Leptochiton lignatilis n. sp. | L. alveolus | L. belknapi |
| Stratigraphy | Miocene of Italy | Pliocene of Italy | - |
| Biogeography | - | Atlantic Ocean | Pacific and Indian Oceans |
| Valves | Thinner and fragile | Thinner and fragile | Thicker and sturdy |
| Tegmental granules | Irregular, rounded-subquadrangular shape | More regular, smaller and closely packed, rounded-oval shape | Larger and more widely spaced, oval to diamond-like in shape |
| Intermediate valves (IV) | Rectangular | Rectangular | Rectangular |
| IV back | Carinated | Arched | Carinated |
| IV anterior margin | Almost straight | Concave in the jugal area | Almost straight |
| IV posterior margin | Almost straight, apex not distinct | Almost straight, apex obsolete or poorly marked | Almost straight, obsolete or poorly marked |
| IV lateral areas | Not raised | Not raised | Little raised, distinctly marked by a diagonal depression |
| IV height/width ratio | 0.50 | - | 0.36 |
| Tail valve (TV) | More than semicircular | Semicircular | Semicircular to roughly triangular |
| TV anterior margin | Convex | Almost straight | Convex |
| TV mucro | Anterior | Central | Subcentral |
