Fissurellidae Fleming 1822

Key to species of Fissurellidae found in the GB (see also Bogi & Giusti 1994 for differentiating Emarginula spp.)

1. Anterior part of the aperture with a deep slit reaching the edge....................................................... 2

– Anterior part of the aperture entire, shell with a slit or a hole not reaching the edge....................... 4

2. Shell height> half length, commarginal sculpture of tightly packed, vermiculate cordlets.............................................................................................. Emarginula christiaensi Piani, 1985 (Fig. 4I–J)

– Shell height ≤ half length, commarginal cords elevated and narrower than intervals...................... 3

3. Apex definitely overhanging the posterior edge of the shell.............................................................. .......................................................................... Emarginula tuberculosa Libassi, 1859 (Fig. 4F–H)

– Apex not overhanging the posterior edge of the shell ................................................................................................................................................. Emarginula multistriata Jeffreys, 1882 (Fig. 4D–E)

4. Shell with a hole situated at the apex or close to it........................................................................... 5

– Shell with a slit situated between the apex and the anterior edge.................................................. 10

5. Apex retaining coiled part with larval shell, and the hole immediately anterior to it...................... 6

– Apex without coiled part, with the hole situated on it...................................................................... 7

6. Shell height> shell length, shell surface smooth.............................................................................................................................. Profundisepta alicei (Dautzenberg & H. Fischer, 1897) (Fig. 6C–D)

– Shell height ≤ shell length, radial sculpture of granulose riblets............................................................................................................................... Profundisepta profundi (Jeffreys, 1877) (Fig. 6E–G)

7. Shell usually large, with a sculpture of radial and commarginal riblets.................................................................................................................. Diodora tenuiclathrata (Seguenza, 1863) (Fig. 4A–C)

– Shell always smaller than 10 mm with a sculpture of minute granules............................................ 8

8. Granules arranged along radial lines................ Fissurisepta granulosa Jeffreys, 1883 (Fig. 6A–B)

– Granules arranged quincuncially...................................................................................................... 9

9. Shell height nearly twice shell length................. Cornisepta rostrata (Seguenza, 1863) (Fig. 6H–J)

– Shell height about the same as shell length................................................................................................................................ Cornisepta microphyma (Dautzenberg & H. Fischer, 1896) (Fig. 6K–M)

10. Shell sculpture formed by definite radial ribs intersecting commarginal cordlets.......................................................................................... Puncturella asturiana (P. Fischer, 1882) [not found on GB]

– Shell sculpture formed by radial rows of granules, aligned to form ribs........................................11

11. Apex strongly curved, overhanging posterior edge.................................................................................................................................................. Puncturella granulata (Seguenza, 1863) (Fig. 4K–L)

– Apex weakly curved, not overhanging posterior edge........................................................................................................................................................... Puncturella agger Watson, 1883 (Fig. 5A–N)