356 



Fishery Bulletin 94(2), 1996 



weight of a similar-size C. opilio from the shelf of 

 the eastern Bering Sea is 739 gm(Somerton, 1981c), 

 considerably heavier than the slope species. The 

 likely explanation for this is that slope species of 

 Chionoecetes, like slope species of king crabs, have 

 proportionately thinner legs than shelf species 

 (Somerton, 1981b). The evolutionary significance of 

 such depth-related changes in shape is unclear, 

 but for other deep-water Crustacea, reduced muscu- 

 lature is assumed to be an adaptation for energy ef- 

 ficiency in a habitat where food is scarce (Childress, 

 1971). 



Similarity of C. angulatus and C. japonicus 



Repeatedly throughout the foregoing discussion, we 

 have compared various distributional or life history 

 characteristics reported from other studies of C. 

 japonicus with those determined for C. angulatus 

 from our samples because we suspect that the two 

 species actually are either taxonomically identical 

 or that C. japonicus is a subspecies of C. angulatus 

 (3 years after Rathbun L1932] described C. japonicus, 

 Derjugin and Kobjakowa [1935] described C. 

 angulatus bathyalis on the basis of specimens that 

 were also collected near Japan). We base our ques- 

 tion not only on the similarity of the various biologi- 

 cal features that we examined (e.g. size and depth 

 distribution, size at maturity) but also on the high 

 degree of similarity in shape between the two spe- 

 cies. We recommend that the validity of the separa- 

 tion of C. angulatus and C. japonicus be re-exam- 

 ined by qualified systematists. 



Acknowledgments 



We thank Allen Shimada for help in sampling, Will- 

 iam Meyers for laboratory analysis of the fecundity 

 samples, and Bob Otto, Bob McConnaughey, and 

 Gerard Conan for reviewing the manuscript. 



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