ID Keys

Key to Abra species

#1
Beaks at midpoint, trigonal, H=L
Abra tenuis
  
Beaks towards posterior H<L
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#2
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Posterior distinctly acute compared to anterior
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Posterior rounded but not acutely, similar to anterior
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#3
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Commarginal growth lines and faint radial striations, found on continental margin and upper slope
Abra longicallus
  
Commarginal growth lines, no radial striations, found on continental shells only
Abra alba
  
#4
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Elongate ovate, beaks a third from posterior of shell
Abra prismatica
  
Subovate, beaks just after midline
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#5
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Depression behind umbo, no deeper than 200m
Abra nitida
  
No depression behind umbo but several tiny ridges present, found below 2000m
Abra profundorum