Key:  Amphipod Suborder Gammaridea, Group II

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 Amphithoe)	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
9b
10a
10b
11a
11b
12a
12b
13a
13b
14a
14b
15a
15b
16a
16b
17a
17b
18a
18b
19a
19b
20a
20b
21a
21b
22a
22b

  Peramphithoe humeralis