Provisional Key to the Families of the Great Lakes Larval Fishes

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2a. Mouth in a sucking disc; eye small; several pairs of gill openings (from 1a)

2b. Mouth with jaws; eye large; single pair of gill openings (from 1a)

3a. Chin barbel (s) present (from 1b)

3b.Chin barbel (s) absent (from 1b)

4a. Mouth terminal; single barbel on lower jaw; usually 10 to 20 mm TL; pigment restricted to dorsum of stomach and head; no dark lateral band (from 3a)

4b. Mouth inferior; several barbels anterior to upper jaw; usually greater than 20 mm TL; dark lateral band evident (from 3a)

5a. Snout produced; dorsal and anal fns set far back on body (from 3b)

5b. Snout short, its length usually less than 10% TL; median fns otherwise (from 3b)

6a. Snout produced but narrow; numerous teeth visible on jaws; snout length usually 18 to 21% (from 5a)

6b. Snout produced but thick (resembles duck bill); teeth not readily apparent; snout length usually 6 to 15% TL (from 5a)

7a. Median fns or fnfolds continuous, or nearly so (from 5b)

7b. Median fns or fnfolds showing distinct separation (from 5b)

8a. Pectoral fns poorly developed; may be buds; single barbel on lower jaw; notochord straight; caudal fn rays developed on dorsal and ventral aspects (from 7a)

8b. Pectoral fns large and usually well developed; lower jaw without barbel; urostyle upturned or notochord straight, if straight caudal fn rays developed on ventral half only (from 7a)

9a. Larva entirely dark with pigment; head large; gular plate developing; notochord straight, caudal fn rays developed on ventral half only; mouth terminal; opercule without spine(s) (from 8b)

9b. Larva sparsely pigmented; often exhibiting “saddle markings” on dorsum; opercule often with spines (s); notochord fexed; mouth subterminal (from 8b)

10a. Adipose fn, or its position, evident (from 7b)

10b. No adipose fn, or demarcation of one, in fnfold (from 7b)

11a. Total myomeres 32 to 34 (from 10a)

11b. Total myomeres greater than 40 OR larva too opaque to count myomeres (from 10a)

12a. Larva robust; small melanophores over body; myomeres not enumerable (body dense) (from 11b)

12b. Larva elongate; melanophores large or restricted in distribution; myomeres enumerable (from 11b)

13a. Pigment restricted to venter; swim bladder evident; myomeres easy to enumerate; eye small 3 to 4% TL; preanal length greater than 70% TL (from 12b)

13b. Large melanophores on dorsal and lateral aspects; swim bladder not evident; myomeres diffcult to distinguish; eye large, greater than 5% TL; preanal length less than or equal to 70% TL (from 12b)

14a. Preanal myomeres greater than or equal to postanal myomeres (from 10b)

14b. Preanal myomeres signifcantly less than postanal myomeres (difference greater than 5 myomeres) (from 10b)

15a. Preanal myomeres approximately equal to postanal myomeres (difference 5 myomeres or less) (from 14a)

15b. Preanal myomeres signifcantly greater than postanal myomeres (difference greater than 5 myomeres) (from 14a)

16a. Postanal myomeres greater than 35; total myomeres greater than 50; single chin barbel in specimens greater than 12 mm TL (from 14b)

16b. Postanal myomeres less than 35; total myomeres less than 50; chin barbel absent (from 14b)

17a. Postanal myomeres greater than or equal to 25; preanal length less than or equal to 40% TL (from 16b)

17b. Postanal myomeres less than 25; preanal length usually greater than 40% TL (from 16b)

18a. Mouth superior; single dorsal fn (from 17b)

18b. Mouth terminal or inferior; usually two dorsal fns (from 17b)

19a. Pectoral fns well developed; head depressed; swim bladder not visible (from 18b)

19b. Pectoral fns poorly developed; head and body compressed; swim bladder visible (from 18b)

20a. Total Myomeres greater than or equal to 35 (from 15a)

20b. Total myomeres less than 35 (from 15a)

21a. Total myomeres less than 26 (from 20b)

21b. Total myomeres between 26 and 34 (from 20b)

22a. Preanal myomeres greater than postanal myomeres; head large and blunt; mouth very large; maxilla extending to or beyond posterior margin of eye; caudal fn lancealate at 12 mm TL (from 21a)

22b. Preanal myomeres usually equal to postanal myomeres (or difference of one); head smaller, pointed; mouth smaller, maxilla extending to middle of eye; caudal fn forked at 12 mm TL (from 21a)

23a. Adipose fn or its position present (from 21b)

23b. Adipose fn or its position absent (from 21b)

24a. Double dorsal fn (from 23b)

24b. Single Dorsal fn (from 23b)

25a. Caudal peduncle thick; total myomeres less than or equal to 31 (from 24b)

25b. Caudal peduncle narrow; total myomeres greater than or equal to 31 (from 24b)

26a. Postanal myomeres usually less than or equal to 10-12 (from 15b)

26b. Postanal myomeres greater than 10-12 (from 15b)

27a. Preanal length 77 to 89% TL; ratio of preanal to postanal myomeres greater than 5 (from 26a)

27b. Preanal length 59 to 73% TL; ratio of preanal to postanal myomeres less than or equal to 5 (from 26a)

28a. Preanal myomeres usually less than 30 (from 26b)

28b. Preanal myomeres usually greater than 30 (from 26b)

29a. Preanal myomeres usually greater than 40 (from 28b)

29b. Preanal myomeres usually less than 40 (from 28b)

30a. Postanal myomeres 14 to 15; preanal length 72 to 75% TL; adipose fn present; swim bladder present (from 29a)

30b. Postanal myomeres 15 to 22; preanal length 67 to 72% TL; adipose fn absent; swim bladder not visible (from 29a)

31a. Preanal length greater than 67% TL; snout elongate (from 29b)

31b. Preanal length less than or equal to 67% TL; snout short and blunt (from 29b)

32a. Adipose fn absent; anal fn rays greater than 20; body usually heavily pigmented (from 31b)

32b. Adipose fn absent; anal fn rays greater than 20; body relatively unpigmented (from 31b)