Morphology Data of Prosopium williamsoni
Identification keys
Main Ref. Scott, W.B. and E.J. Crossman, 1973
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral fusiform / normal
Cross section compressed
Dorsal head profile clearly convex
Type of eyes more or less normal
Type of mouth/snout more or less normal
Position of mouth terminal
Type of scales cycloid scales

Body slender, elongate, nearly cylindrical in cross section but variable, more compressed laterally than round whitefish. Head short; eye moderate, its diameter less than snout length; snout more or less pointed, compressed laterally, pinched, rounded in lateral view, a single flap of skin present between nostrils. Mouth small, ventral in position, overhung by snout; maxillaries extending posteriorly almost to anterior margin of eye in adults. Teeth small, restricted to a small patch on tongue and on gill rakers in adults, although small teeth may be present on the premaxillaries in young, but absent from jaws, vomer, palatines and pre maxillae in adults. Overall coloration silvery, but light or dark brown or olive on back, becoming silvery in sides and white below. Scales, specially on back, may have pigmented borders. dorsal fin often dusky, pelvic and pectoral fins in adults with amber tint.

Ease of Identification

Meristic characteristics of Prosopium williamsoni

Lateral Lines 1 Interrupted: No
Scales on lateral line 74 - 90
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Barbels 0
Gill clefts (sharks/rays only)
Gill rakers
on lower limb 11 - 15
on upper limb 8 - 11
total 19 - 26
total 53 - 61


Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   
Spines total 0 - 0
Soft-rays total 11 - 15
Adipose fin present

Caudal fin

Attributes forked; more or less normal

Anal fin(s)

Fins number 1
Spines total 0 - 0
Soft-rays total 10 - 13

Paired fins

Pectoral Attributes  more or less normal
Spines     0
Soft-rays   14 - 18
Pelvics Attributes  more or less normal
Position    abdominal  behind origin of D1
Spines     0
Soft-rays   10 - 12
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
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