Key:  Amphipod Suborder Gammaridea, Group II

(Uropod 3 biramous, both rami shorter than the peduncle)

Phylum Arthropoda
  Subphylum Crustacea
    Class Malacostraca
      Subclass Eumalacostraca
        Superorder Peracarida
          Order Amphipoda
            Suborder Gammaridea

Taken primarily from  Kozloff, 1987, 1996 p. 355 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)
  Original Key created by Craig P. Staude (see reference above)
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Lower taxonomic level Main Page Alphabetic Index Systematic Index Glossary
1a  Outer ramus of uropod 3 with 1 or 2 curved apical spines or teeth (photo) 2
1b Neither ramus of uropod 3 with curved apical spines or teeth (apical spines, if present, are small and straight) 15
2a Outer ramus of uropod 3 with 2 curved apical spines; inner ramus of uropod 3 flattened, with setae as well as spines; outer lobe of lower lip with a deep cleft (Family Ampithoidae) 3
2b Outer ramus of uropod 3 with a single hooked apical spine and some smaller proximal teeth; inner ramus of uropod 3 conical, with one or more spines but no setae; outer lobe of lower lip broadly rounded, not cleft 14
3a Accessory flagellum present and consisting of about 3-5 articles Cymadusa uncinata
3b Accessory flagellum absent or consisting of a single minute article 4
4a Palm of gnathopod 1 nearly transverse (slightly oblique to nearly chelate); article 2 of pereopods 3 and 4 ovate; uropod 1 with a distal  peduncular tooth extending between the rami (Genus Peramphithoe) (photo) 5
4b Palm of gnathopod 1 distinctly oblique; article 2 of pereopods 3 and 4 rectangular; uropod 1 without a distal  peduncular tooth (Genus Ampithoe) 9
5a Adults 2-3 cm in length; proximal  flagellar  articles of antenna 2 typical, not fused; gnathopod 2 of male only slightly enlarged, if at all 6
5b Adults rarely over 1 cm; proximal  flagellar  articles of antenna 2 usually fused into a single article which is distinctly longer than the subsequent articles; gnathopod 2 of male distinctly enlarged 7
6a Article 5 of gnathopod 1 distinctly longer than article 6; gnathopod 2 of male not obviously different from gnathopod 1; pereopod 7 longer than pereopod 6 Peramphithoe humeralis
6b Articles 5 and 6 of gnathopod 1 nearly equal in length; article 6 of gnathopod 2 of male about twice as broad as in gnathopod 1; pereopods 6 and 7 nearly equal in length Peramphithoe mea
7a
7b
8a
8b
9a Posteroventral corner of epimera 2 and 3 with a blunt but distinct tooth 10
9b Posteroventral corner of epimera 2 and 3 rounded or forming a right angle, but without a distinct tooth 11
10a
10b
11a Article 6 of gnathopod 2 of male rectangular, its palm nearly transverse and somewhat convex 12
11b Article 6 of gnathopod 2 of male ovate, its palm strongly oblique and concave or incised 13
12a
12b
13a Antennae and uropods with close-set, long setae (setae of antennal peduncles longer than twice the width of each article); gnathopod 2 of male with a narrow excavation between the thumb and dactylar hinge Ampithoe sectimanus
13b Antennae and uropods with sparse, short setae (nearly all setae of antennal peduncles shorter than the width of each article); gnathopod 2 of male with a wide, shallow excavation between the thumb and dactylar hinge Ampithoe dalli
14a
14b
15a
15b
16a
16b
17a
17b
18a
18b
19a
19b
20a
20b
21a
21b
22a
22b



Taxonomic Levels Represented in This Key:

  Ampithoe dalli
  Peramphithoe humeralis



Page created by Dave Cowles, 2007
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