Key to genera and species of the superfamily Cuspidarioidea found on GB

1. Sculpture with definite radial ribs ..................................................................................................... 2

– Sculpture only commarginal (may include faint ridges from umbo to posterior part), or surface of shell smooth .................................................................................................................................. 3

2. Two strong radial ribs on posterior half, anterior with commarginal undulations .............................. .................................................................................. Myonera paucistriata Dall, 1886 (Fig. 41A‒C)

– Numerous fine radial ribs on posterior half ...... Cardiomya cadiziana M. Huber, 2010 (Fig. 41G‒I)

3. Posterior rostrum short and stout ...................................................................................................... 4

– Posterior rostrum tapering ................................................................................................................ 6

4. Shell inflated, smooth and glossy ................. Jeffreysomya truncata (Jeffreys, 1882) (Fig. 41D‒F)

– Shell compressed, with marked growth lines and wrinkles on posterior part .................................. 5

5. An anterior lateral tooth on the right valve ......................................................................................... ........................................................... Protocuspidaria verityi Allen & Morgan, 1981 (Fig. 43 D‒G)

– No teeth on either valve .................. Protocuspidaria simplis Allen & Morgan, 1981 (Fig. 43 H‒K)

6. Hinge of right valve with a small knob-like cardinal and no lateral teeth; posterior rostrum pointed, not definitely distinct from rest of the shell .... Halonympha depressa (Jeffreys, 1882) (Fig. 43 A‒C)

– Hinge of right valve with at least one (posterior) lateral tooth ............................................................7

7. Hinge of right valve with anterior and posterior lateral teeth (genus Rhinoclama) ......................... 8

– Hinge of right valve with only a posterior lateral tooth ...................................................................... ....................................................................... Cuspidaria cf. rostrata (Spengler, 1793) (Fig. 42G‒I)

8. Posterior part of shell (excluding rostrum) with widely spaced commarginal cordlets; anterior lateral long and lamellar ...................................... Rhinoclama semistrigosa (Jeffreys, 1882) (Fig. 42D‒F)

– Posterior part of shell (excluding rostrum) with growth lines only; anterior lateral short and bulging ................................................................... Rhinoclama teres (Jeffreys, 1882) (Fig. 42A‒C)