GILBERT: FISHES OF THE SUBGENUS LUXILUS


which ruled (Jordan, 1916: 28) that a diagnosis, no matter how brief,
constitutes a description providing there is no reasonable doubt as
to the identity of the species involved.
 DIAGNOSIS. A species of Luxilus distinguished from other mem-
bers of the subgenus by the following characters: Anterior dorso-
lateral scales relatively small, numbering (16) 18 to 24 (30); circum-
ferential scales (26) 30 to 35 (39); sum of anterior dorso-lateral and
circumferential scales (42) 48 to 59 (69); mid-dorsal stripe gray-blue,
turning to brilliant golden in live breeding males; a light olive stripe,
slightly wider than dorsal stripe extending along body on either side
of dorsal stripe (figure 15D); below this is another dark stripe, the
same width as the dorsal stripe, which also becomes brilliant golden
in breeding males; pigment usually absent from chin and gular region
(figure 9A), particularly on specimens from west of the Alleghenies.
 Further distinguished from the closely related N. albeolus by the
following characters: Anterior dorso-lateral and circumferential scales
smaller (for counts see preceding paragraph, table 7, and tables 9
through 11); considerable red pigment always present on body and
fins of nuptial males, usually absent or subdued in breeding females;
color of dorsal region olive-brown; scale pockets along side of body
usually with considerable pigment, forming prominent crescent-shaped
bars, particularly in breeding males; side of body with a bronzy
aspect in life, as contrasted to the more silvery aspect of N. albeolus;
body deep and compressed; maximum size apparently somewhat
larger.
 DESCRIPTION. Fin ray and scale row counts and body propor-
 tions were taken on varying numbers of specimens; these appear in
 tables 6, 7, and 9 through 15. Characters mentioned in the diagnosis
 are not repeated in the following paragraph:
 One of the largest forms of Notropis, the males sometimes attain-
 ing a length of 175 mm or more; sides of body silvery-bronze, with a
 pink wash in breeding males; breast and belly silvery, with little or
 no pink in breeding males; pigment wholly or partly absent on chin
 and gular region in most populations west of the Appalachian Moun-
 tains, variable in most populations east of the mountains; top of head
 blue-brown, becoming deep blue-gray in breeding males; sides of
 head lighter gray than top; branchiostegals ordinarily colorless, but
 light rosy in breeding males; dorsal fin slightly dusky, often becoming
 notably darkened in breeding males; other fins normally plain; breed-
 ing males pink or red on distal third or fourth of all fins.


1964