Keys to Nature
Project
Key to the Mussels of the Chicago Wilderness Region


© James Bland & Laura Barghusen Mussel Key Terms - Keys to Nature Project

Title:
Key to the Mussels of the Chicago Wilderness Region
Revisions:
120
Author(s):
Roger Klocek, James Bland, Laura Barghusen
Email:
rklocek@openlands.org, lbarghusen@openlands.org, ilmbland@comcast.net
Description:

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Key Structure:
1. shells less than 2 inches long with no teeth OR two sets of similar looking teeth. 2
1. shells of any size with visible lateral and/or pseudocardinal teeth. 5

2. small, elongated shells with no apparent teeth 3
2. shells with a pair of lateral teeth in each half 4

3. shell can stand on flat side without toppling - zebra mussel
3. shell can not stand on flattened side without toppling - quagga mussel

4. less than 2 inches, with heavy, regularly spaced, raised lines on shell - Asiatic clams
4. less than 1/2 inch, thin shelled, with very fine to medium lines on shell surface - fingernail clams
4. shells less than 2 inches long and with heavy, exaggerated ornamentation on beak -juvenile mussels - beyond the scope of this key

5. Shells with bumps, knobs, ridges or flutes on external surface 6
5. Shells without bumps, knobs, ridges or flutes externally 12
5. shells less than 2 inches long and with heavy, exaggerated ornamentation on beak -juvenile mussels - beyond the scope of this key

6. shells with ridges or flutes on external surface 7
6. Shells with bumps or knobs on external surface 8

7. shells with one and usually at least three ridges but without marks below the beak threeridge
7. shell with at least 3 ridges and raised markings below beak - washboard
7. shells with flutes on posterior edge - fluted shell

8. shells with small bumps: bumps not arranged in recognizable rows 9
8. shells with large bumps or knobs; bumps arranged in rows 10

9. somewhat rounded shells with several to many small bumps and indistinct greenish markings on beak pimpleback
9. shell somewhat rounded with many small bumps and usually purplish nacre but never with greenish markings on the beak - purple wartyback
9. shell elongated with many small bumps pistolgrip

10. shell with small to large bumps arranged in two rows mapleleaf
10. shells with large bumps or knobs not arranged in two rows 11

11. shells with knobs or large bumps in a single row on thickened growth rings sheepnose
11. shells with knobs and bumps as well as a distinctive shape monkeyeface

12. shells that have a length to width ratio of 2:1 or nearly so 13
12. shells that have a length to width ratio that is less than 2:1 16

13. shells that have a darker colored exterior surface (periostracum) 14
13. shells generally with a lighter colored external surface (periostracum) 15

14. shell is thinner, more compressed and has the posterior tip pointing downward spike
14. shell is thicker, more inflated, more circular in cross section, and has the tip pointing medially or upward - black sand shell

15. shell yellowish brown to darker brown with no rays; beak has radiating sculpture pondhorn
15. shell yellowish, sometimes with some rays; beak with double-looped sculpture - yellow sandshell
15. shell yellowish with distinct broken rays and distinct beak sculpture rainbow

16. wide, somewhat compressed shells with dark brownish periostracum (exterior surface) and a distinct wing 17
16. wide, somewhat compressed shells with a less pronounced wing and often having a lighter colored periostracum 18
16. wide, somewhat compressed to inflated shells with a less pronounced wing and often having a lighter colored periostracum 20

17. large teeth with white nacre and double looped beak sculpture - white heelsplitter
17. medium pseudocardinal teeth with pink nacre and relatively smooth beak sculpture- pink heelsplitter

18. thick shell, can't easily be broken by fingers, white to yellowish nacre, distinct, looped beak sculpture - creek heelsplitter
18. thin shell, can be broken with fingers, white to pink nacre, beak sculpture indistinct -19

19. thin shell, smaller wings, white to somewhat pinkish nacre, external shell surface a bit rough - fragile papershell
19. thin shell, usually larger wings, nacre pink to purple, shell relatively smooth - pink papershell

20. thin shells with reduced or absent pseudocardinal teeth 21
20. thicker shells with medium to large teeth 24
20. shell thin to moderately thick with small to medium sized teeth 31

21. shell with beaks that are flat, not raised above the hinge line - paper pondshell
21. shells with beaks noticeably raised above hinge line 22

22. shell without internal teeth and having double looped beak sculpture - giant floater
22. shell without teeth or with indistinct teeth and without double-looped beak sculpture 23

23. shell with no teeth and beak sculpture that is very fine; with a smoothly- rounded, indistinct, posterior ridge externally - cylindrical papershell
23. shell with no teeth or indistinct teeth; beak sculpture that is heavy or coarse; with a pronounced posterior ridge externally elktoe
23. shell with no or indistinct teeth & beaks with two or three thickened ridges, and an indistinct posterior ridge creeper

24. thicker shells with medium or large teeth & roughly triangular shape 25
24. thicker shells with medium or large teeth and not roughly triangular shaped 27
24. shell thin to moderately thick with small to medium sized, less massive teeth 31

25. roughly triangular shaped shells with a sulcus - Wabash pigtoe
25. roughly triangular shells without a sulcus 26

26. roughly triangular and beaks noticeably angled anteriorly; usually distinctly striped externally butterfly
26. roughly triangular, beaks not dramatically angled forward and usually eroded beaks - elephant ear

27. thick shells with medium to large teeth, fine beak sculpture and roughly rounded or squat-oblong in shape - round pigtoe
27. relatively thick shells with medium teeth 28
27. thin to moderately thick shells with smaller teeth 29

28. thick shells with medium to large teeth, fine beak sculpture and shell noticeably longer than wide - mucket
28. adult shell thick, with medium teeth , coarse beak sculpture and shell somewhat wider and more inflated - plain pocketbook
28. shell thin to moderately thick with less massive teeth 31

29. thinner shells with smaller teeth; shell outline is moccasin shaped 30
29. thin to moderately thick shells with smaller teeth that are not moccasin shaped 31

30. small moccasin shaped shell under 2 inches with thick beak sculpture and small teeth - lilliput
30. large moccasin shaped shell with fine double-looped beak sculpture and medium teeth - female fatmucket

31. thinner shells, not moccasin shaped, with smaller teeth and heavy, thick beak sculpture 32
31. thinner shells, smaller teeth, not moccasin shaped with somewhat triangular shell 33
31. thinner shell, less triangular and more elongated in shape with medium teeth 34

32. very thin, elongated shell with very small teeth and coarse, thickened beak sculpture - salamander mussel
32. small, thin shell with small teeth; truncated posterior end and thickened lines as a beak sculpture slippershell

33. moderately thick shell, small teeth, somewhat triangular in shape with a sharply angled posterior ridge deertoe
33. moderately thick shell, small teeth, somewhat elongated with a more rounded posterior ridge fawnsfoot

34. moderately thick and elongated shell, medium teeth, fine unique beak sculpture - male fatmucket
34. moderately thick shell, medium teeth, broad beak, distinctive markings snuffbox
34. moderately thick, elongated shell, with broad green rays and medium teeth, - ellipse

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This page was last modified on: Wed, 20 Jul 2016 09:17:50 -0500.