Key:  Families Pectinidae and Propeamussidae

Phylum Mollusca
 Class Bivalvia
  Subclass Pteriomorpha
    Order Ostreoida
      Suborder Pectinina

Taken primarily from  Kozloff, 1987, 1996 p. 273 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)
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1a  Only the right valve decidedly convex (the left valve is fairly flat); height commonly exceeding 10 cm Patinopecten caurinus
1b Both valves decidedly convex; height less than 7 cm (except in the case of Hinnites giganteus (now Crassodoma gigantea), which reaches a height of more than 10 cm; this species, after reaching a height of about 1 cm, becomes permanently cemented to rock) 2
2a Interior of both balves with purple blotch; free-living until about 1 cm high, then becoming cemented to rock by the right valve; height often exceeding 10 cm Crassodoma gigantea
(in key as Hinnites giganteus)
2b Interior of both valves without a purple blotch near the hinge; not permanently cemented to rock (but it may be temporarily attached by a byssus); height not more than 6 cm 3
3a With true external ribs (there may also be ruffles or spines, but if these are worn away, the ribs will still be evident); height commonly greater than 3 cm 4
3b Either without ribs or only with pseudoribs which consist of raised ruffles of the concentric ridges (if the ruffles, which may overlap one another, are scraped away, no rib remains) 6
4a Radial ribs of both valves with very prominent spines or ruffles, rough to the touch Chlamys (Chlamys) hastata
4b Valves nearly or quite smooth to the touch (if the ribs have spines or knoblike excresences, these are so slight as to be invisible without magnification; the excresences, moreover, are generally restricted to the right valve) 5
5a Both valves with about 20-30 prominent ribs (ribs of the right valve with ruffles but those of the left valve smooth; common shallow subtidal species) Chlamys (Chlamys) rubida
5b Both valves with about 10 especially prominent ribs, between which are less prominent ribs (rare subtidal species in our region) Chlamys (Chlamys) behringiana
6a With raised internal ribs (height up to 2.5 cm) Family Propeamussidae:
Parvamussium alaskensis
6b Without raised internal ribs 7
7a Either without pseudoribs or with pseudoribs that are about the same caliber as the concentric ridges (height up to 3 cm) Delectopecten randolphi
7b With pseudoribs that are much more pronounced than the concentric ridges Delectopecten vancouverensis

Taxonomic Levels Represented in This Key:
Chlamys (Chlamys) behringiana
Chlamys (Chlamys) hastata
Chlamys (Chlamys) rubida
Delectopecten randolphi
Delectopecten vancouverensis
Hinnites giganteus
Parvamussium alaskensis
Patinopecten caurinus

Page created by Dave Cowles, 2005
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