Aspidosiphonidae, Baird, 1868

Family Aspidosiphonidae View in CoL

1. Hooks, if present, not in rings ....................................... Aspidosiphon ( Akrikos) albus Murina, 1967 View in CoL

– Hooks in rings on the distal region of the introvert.........................................................................2

2. Longitudinal muscle layer divided into separate (or anastomosing) bundles ...................................... ................................................................................................ Aspidosiphon ( Paraspidosiphon) View in CoL ........3

– Longitudinal muscles in continuous layer (except under anal shield) ............................................... ..................................................................................................... Aspidosiphon ( Aspidosiphon) View in CoL ........7

3. Anal shield with grooves...................................................................................................................4

– Anal shield without grooves..............................................................................................................5

4. Papillae of anterior trunk scattered ..... Aspidosiphon ( Paraspidosiphon) laevis de Quatrefages, 1865 View in CoL

– Papillae of anterior trunk in lines .............................. Aspidosiphon ( Paraspidosiphon) cutleri sp. nov.

5. Compressed hooks bidentate, followed by dark pyramidal hooks ..................................................... ............................................................ Aspidosiphon ( Paraspidosiphon) steenstrupii Diesing, 1859 View in CoL

– Compressed hooks bidentate, followed by pale pyramidal hooks....................................................6

6. Hooks bidentate, with streak vertical on the superior region ............................................................. .............................................................. Aspidosiphon ( Paraspidosiphon) fischeri ten Broeke, 1925 View in CoL

– Hooks bidentate, with streak oblique on the superior region ............................................................. ............................................................................. Aspidosiphon ( Paraspidosiphon) pastori sp. nov.

7. Individual units form into longitudinal ridges over dorsal half of anal shield .................................. ...................................................................... Aspidosiphon ( Aspidosiphon) muelleri Diesing, 1851 View in CoL

– Without individual units that form into longitudinal ridges over dorsal half of anal shield.........8

8. All hooks unidentate; ill-defined anal shield ....................................................................................... ................................................... Aspidosiphon ( Aspidosiphon) gracilis schnehageni Fischer, 1912 View in CoL

– Distal hooks bidentate; anal shield well-defined.............................................................................9

9. All compressed hooks bidentate, followed by dark conical hooks ..................................................... ............................................ Aspidosiphon ( Aspidosiphon) elegans ( Chamisso & Eysenhardt, 1821) View in CoL

– Distal bidentate compressed hooks, followed by proximal unidentate ones..............................10

10. Gut helicoidal; lives in gastropod shells; anal shield units not tightly packed and of similar size ........................................................................ Aspidosiphon ( Aspidosiphon) gosnoldi Cutler, 1981 View in CoL

– Gut coils loose or absent; does not occupy gastropod shells; anal shield more solid, with closeset, granular units of differing sizes ............. Aspidosiphon ( Aspidosiphon) misakiensis Ikeda, 1904 View in CoL