ID Keys
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Key to Nuculidae species

#1
Shell higher than long
Go to #2
  
Shell longer than high
Go to #3
  
Growth stages clear, widely spaced, found to edge of shelf (to 200m)
Nucula nucleus
  
Initial smooth appearance, but fine commarginal lines, found below 2000m
Brevinucula verrilli
  
Ovate/subovate outline
Go to #4
  
Trigonal outline
Go to #6
  
Posterior and anterior margins almost straight, sculpture of raised granules, depths from 500 to 2000m
Ennucula granulosa
  
Posterior and anterior margins rounded, no granulations on surface
Go to #5
  
Posterior and anterior margins broadly rounded, radial riblets and commarginal lines, crenulate inner margin, 500-4000m,
Nucula atacellana
  
Anterior broadly rounded, posterior convex lunule margin, postrior tip acutely rounded, commarginal sculpture, 200-4000m
Ennucula corbuloides
  
Commarginal sculpture only
Go to #7
  
Radial lines or riblets, giving decussate appearance in older shells
Go to #9
  
A northern species - Norwegian shelf (200-500m), commarginal sculpture, elongate trigonal outline - anterior margin very long, very tumid shell, swollen umbos
Ennucula corticata
  
Not restricted to the north, British shelf or abyssal slope (to 4000m), umbos not swollen but can be prominent
Go to #8
  
Umbos prominent, point up, found to 4000m, pale, straw coloured periostracum, angular posterior margin
Ennucula corbuloides
  
Umbos can be eroded, point towards posterior, found to 200m, oliver green to brown periostracum, rounded posterior margin
Ennucula tenuis
  
Periostracum appears matt. Posterior margin curved, lunule protrudes
Go to #10
  
Periostracum appears glossy, even when dry. Glossy greenish, lunule barely noticeable in profile, flattened.
Nucula nitidosa
  
Ignoring the lunule, the posterior margin is concave, curving in slightly. Corrugations on lunule, often coated in black manganese deposit
Nucula sulcata
  
Ignoring lunule postreior margin is straight. No corrugations on lunule, often coated in manganese,
Go to #11
  
Moderately tumid, matt periostracum, grey green to olive, often coated in Manganese deposit, commarginal bands are common, rarely with rays
Nucula nucleus
  
Shell compressed, not tumid, smooth silky to matt periostracum, grey green to olive, frequently with orange or reddish rays and sometimes commarginal bands
Nucula hanleyi