Part 2

METHODS, MATERIALS AND ACKNOWLEDGMENTS

Ten meristic characters and seventeen measurements of body-parts (the latter expressed as proportions of standard length) have been analyzed. They are: number of rays in the dorsal, anal, caudal, pectoral and pelvic fins; number of scales in the lateral line, before the dorsal fin, around the body and around the caudal peduncle; number of vertebrae; body-depth, depth of caudal peduncle, length of caudal peduncle, predorsal length, length of depressed anal and dorsal fins, length of pectoral and pelvic fins, head-length, head-depth, head-width, snout-length, postorbital length of head, length of orbit, interorbital width, length of upper jaw and width of gape.

Counts and measurements were made as described by Hubbs and Lagler (1958), with the exception of scales before the dorsal fin, which were counted as the number of vertical scale-rows between the upper margin of the opercular cleft and the origin of the dorsal fin. Vertebral counts, made from roentgenograms, excluded vertebrae in the Weberian complex (presumably always four) but included the hypural vertebra.

Counts and measurements were made on series (usually ten fish) from localities throughout the range. To minimize effects of allometric growth, the fish were divided into several length-groups prior to analysis of proportional measurements: 30-50mm, 50-70mm, 70-100mm, 100-150mm, 150-200mm and 200mm standard length and over. The majority of specimens examined were 70-100mm in standard length.

Specimens were obtained from the following institutions: University of Alberta (abbreviated UA in the text); Museum of Zoology, University of Michigan (UMMZ); University of Missouri (UM); Montana State College (MSC); University of Oklahoma Museum of Zoology (UOMZ); University of Saskatchewan; Royal Ontario Museum, Division of Zoology, Toronto (ROMZ); University of Wyoming (WU); Museum of Natural History, University of Kansas (KU). Specimens examined are listed in the accounts of the subspecies.

We are grateful to D. A. Boag, Reeve M. Bailey, Arthur L. Witt, C. J. D. Brown, Carl Riggs, F. M. Atton, W. B. Scott, and George Baxter, all staff-members of the institutions listed in the immediately preceding paragraph, for placing specimens at our disposal. Mr. William Peters analyzed the contents of stomachs of specimens that were used for study of the food habits. Mr. Artie L. Metcalf assisted in collecting specimens. Drs. Kenneth B. Armitage and E. Raymond Hall offered valued suggestions in connection with the preparation of the manuscript.

DESCRIPTION OF THE SPECIES

=Hybopsis gracilis= (Richardson)

Flathead Chub

(Synonymy under accounts of subspecies)

Description.--Pharyngeal teeth 2,4-4,2, hooked; dorsal fin of moderate size, falcate, first principal ray longest, extending beyond posterior rays in depressed fin, its origin usually slightly in front of insertion of pelvic fin, approximately equidistant from tip of snout and base of caudal fin, rays 8, rarely 9; pectoral fin strongly falcate, rays 14-20, usually 16-18; pelvic rays 8, rarely 9; anal fin falcate, rays 8, rarely 9; caudal rays 19, rarely 20.

Body slightly compressed, nearly terete; head-length 23.1-28.8 per cent of standard length; head broad and flattened, snout subconical, premaxillae protractile, upper lip not medially expanded; mouth subterminal, nearly horizontal, large; a single pair of terminal maxillary barbels; orbit usually 5-7 per cent of standard length; lateral line slightly decurved; intestine short, peritoneum silvery.

Color brown or olivaceous dorsally, silver or creamy white ventrally, without distinctive markings; dusky lateral band evident in preserved specimens.

Taste-buds present on membrane between first and second principal rays of all fins, and on first to sixth interradial membranes of pectoral fin. On the caudal fin, taste buds between first and second principal rays of upper and lower lobes, though present, are less well developed than on other fins. Moore (1950:88) states that taste buds are numerous on the barbels, cheeks, lips, chin, snout, opercles and branchial membranes, and are present in decreasing numbers over the body.

Nuptial tubercles of male minute and densely scattered over top of head and snout; usually present on pectoral rays 1-8, weak when present on rays beyond the eighth, never found beyond the eleventh ray; minute tubercles usually found on dorsal, pelvic and anal fins, rarely on lower scales of caudal peduncle; predorsal scales have a fine peripheral row of tubercles.

=Hybopsis gracilis gracilis= (Richardson)

(Plate 22)

Cyprinus (Leuciscus) gracilis Richardson, 1836:120 and Pl. 78 (original description; Saskatchewan R. at Carlton House).

Coregonus angusticeps Cuvier and Valenciennes, 1848:534 (original description; Saskatchewan R.).

Pogonichthys communis Girard, 1856:188 (in part; original description); Girard, 1858:247 and plate 55 (in part; characters; synonymy); Suckley, 1860:361 (Milk R.); Cope, 1879:440 (Fort Benton, Mo. R.; Judith R.).

Platygobio gracilis, Jordan and Gilbert, 1882:219 (in part; characters; synonymy); Graham, 1885:74 (Kansas R.; synonymy); Jordan, 1885:29 (records); Jordan and Meek, 1886:13 (Mo. R., St. Joseph, Mo.); Meek, 1892:245 (characters; Mo. R., Sioux City, Iowa); Eigenmann, 1895:111 (Craig; Poplar; Brandon; Medicine Hat); Meek, 1895:137 (Platte R., Fremont, Neb.); Evermann and Cox, 1896:412 (in part; habitat; synonymy); Jordan and Evermann, 1896:326 (in part; characters; synonymy); Thompson, 1898:214 (Brandon; Saskatchewan R.); Evermann and Goldsborough, 1907:98 (records from Canada); Forbes and Richardson, 1920:170 (characters; habitat; synonymy; records from Illinois; but Fig. 45 is Hybopsis meeki Jordan and Evermann, not H. gracilis); Hankinson, 1929:446 (records from North Dakota); Jordan, 1929:76 (in part; characters); Jordan, Evermann and Clark, 1930:136 (in part; synonymy); Churchill and Over, 1933:45 (characters; food; habitat; spawning; records from South Dakota); O'Donnel, 1935:481 (Ohio R., Cairo, Ill.; Miss. R., Chester, Ill.); Hinks, 1943:57 (records from Canada); Clemens, et al., 1947:17 (records from Saskatchewan); Dymond, 1947:19 (distribution in Canada); Rawson, 1951:208 (Great Slave Lake; Mackenzie R.); Shoemaker, Pickering and Durham, 1951:84 (Miss. R., Cates, Tenn.; Miss. R., between Hickman and Barfield, Ark.); Wynne-Edwards, 1952:18 (distribution in Canada); Miller and Paetz, 1953:47 (Peace R. at town of Peace River); Walters, 1955:347 (distribution in Canada; dispersal into Canada); Keleher, 1956:265 (Saskatchewan R., Manitoba); Lindsey, 1956:771 (distribution in Canada); Keleher and Kooyman, 1957:110 (Kelsey Lake, Manitoba); Lindsey, 1957:657 (Laird and Peace drainages, British Columbia); Scott, 1958:16 (distribution in Canada); Slastenenko, 1958:7 (distribution in Canada).

Platygobio pallidus Jordan and Gilbert, 1882:220 (original description; Ohio R., Cairo, Ill.); Jordan and Evermann, 1896:326 (characters; synonymy; Ohio R., Cairo, Ill.); Jordan, Evermann and Clark, 1930:136 (Ohio R., Cairo, Ill.; synonymy).

Platygobio gracilis communis, Simon, 1946:71 (in part; characters; food; habitat; spawning); Moore, 1950:87 (habitat; sense organs).

Hybopsis gracilis communis, Bailey, 1951:192 (record from Iowa; key); Harlan and Speaker, 1951:75 (characters; distribution in Iowa); Hubbs, 1951:9 (habitat; Miss. R.); Harrison and Speaker, 1954:516 (habitat); Personius and Eddy, 1955:42 (habitat; Little Mo. R.).

Hybopsis gracilis, Cleary, 1956:271 (record from Iowa; distributional map); Bailey, 1956:332 (record from Iowa; key); Harlan and Speaker, 1956:90 (characters; distribution in Iowa); Eddy, 1957:111 (in part; characters; key); Moore, 1957:110 (in part; key); Underhill, 1959:100 (Vermillion R., South Dakota).

Diagnosis.--Post-Weberian vertebrae 40-42, usually 41-42; lateral line scales 50-56; pectoral rays 15-20, usually 17 or more; head-depth 12.3-15.1 per cent of standard length, usually 14.7 per cent or less. See Figs. 1 and 2.

Other characters.--Circumference scale-rows 31-42; predorsal scale-rows 20-29; size large, as much as 246 mm standard length (see Fig. 1 of Pl. 24); head-length 23.4-27.4 per cent of standard length, usually 25.5 per cent or less; postorbital length of head 10.9-13.9 per cent of standard length, usually 12.5 per cent or less; predorsal length 46.0-51.7 per cent of standard length; orbit 5.1-6.8 per cent of standard length; prepelvic length 46.6-52.2 per cent of standard length; caudal peduncle length 17.2-22.1 per cent of standard length.

Range (Plate 21).--Mackenzie Basin south from Fort Good Hope; Saskatchewan Basin east to Lake Winnipeg; mainstream of Missouri River and Mississippi River south to Barfield, Arkansas; intergrading with H. g. gulonella in upper Missouri Basin and lower parts of major tributaries to Missouri River in Nebraska and Kansas.