Key:  Family Majidae

Phylum Arthropoda
 Subphylum Crustacea
  Class Malacostraca
    Subclass Eumalacostraca
     Superorder Eucarida
      Order Decapoda
        Suborder Pleocyemata
         Infraorder Brachyura (true crabs)

Taken primarily from  Kozloff, 1987, 1996  p. 413 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)

An updated key can be found on page 303 in Wicksten, 2009.
 
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Lower taxonomic level Main Page Alphabetic Index Systematic Index Glossary

 
1a  Rostrum about half the length of the rest of the carapace, consisting largely of 2 slender, spinelike processes (these may be fused medially for much of their length) 2
1b Rostrum not more than one-third or two-fifths the length of the rest of the carapace, consisting of 2 broad, flattened processes (picture) 3
2a Spinelike processes of rostrum nearly parallel, at least in the proximal half; dorsal surface of carapace with a large, sharp tooth behind each eye (picture) but otherwise rather smooth Oregonia gracilis
2b Spinelike processes of rostrum diverging proximally as well as distally; dorsal surface of carapace without a prominent tooth behind the orbit of each eye, but otherwise rather spiny Chorilia longipes
3a Carapace, including the rostrum, about as wide as, or wider than, long 4
3b Carapace, including the rostrum, decidedly longer than wide 6
4a Carapace, viewed from above, nearly hexagonal; lateral margins of carapace extended into thin, winglike sheets, each with 2 sharp-tipped lobes; dorsal surface of carapace nearly smooth; intertidal as well as subtidal Mimulus foliosus
4b Carapace, viewed from above, broadly oval to circular, lateral margins of carapace not extended into winglike sheets with lobes; dorsal surface of carapace with tubercles or spines, or both; strictly subtidal 5
5a Rostrum sharply inclined upward; dorsal surface of carapace spiny; generally at depths greater than 1000 m Chionoecetes angulatus
5b Rostrum not sharply inclined upward; dorsal surface of carapace roughened by tubercles but not especially spiny; at depths as shallow as 20 m Chionoecetes bairdi
6a Carapace with a prominent, sharp projection, directed outward or slightly forward on both sides of the body near or behind the middle 7
6b Carapace without a prominent, sharp projection on both sides of the body near or behind the middle (such projections, if any, are limited to the anterior half of the body) 9
7a Dorsal surface of carapace almost smooth; distance between the eyes less than about 1/3 the greatest width of the carapace Pugettia producta
7b Dorsal surface of carapace with tubercles; distance between the eyes about 1/2 the greatest width of the carapace. 8
8a Dorsal surface of merus of cheliped with some tubercles, but not with a distinct ridge; posterolateral expansions of carapace much broader basally than the next expansions anterior to them Pugettia richii
8b Dorsal surface of merus of cheliped with an irregularly toothed ridge; posterolateral expansions of carapace only slightly broader than the next expansions anterior to them Pugettia gracilis
9a Outline of body, as viewed from above, lyre-shaped, owing to a toothed expansion of the carapace on both sides of the anterior half; rostral processes widest at the base (picture) 10
9b Outline of body, as viewed from above, nearly triangular, becoming narrowed gradually toward the eyes; rostral processes widest near the middle Scyra acutifrons
10a Length of carapace, including rostrum, about 1.5 times the width; at depths of 500 m or more Oregonia bifurca
10b Length of carapace, including rostrum, about one and one-fifth times the width; in shallow water as well as at considerable depths Hyas lyratus



Taxonomic Levels Represented in This Key:

  Chionoecetes bairdi
  Chorilia longipes
  Hyas lyratus
  Oregonia gracilis
  Pugettia gracilis
  Pugettia producta
   Scyra acutifrons



Page created by Dave Cowles, 2005
Edited by:  Dave Cowles 2006-2011