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<br />may be distinctive. The recent connection between the Virgin and
<br />Moapa Rivers, prior to the filling of Lake Mead, suggests a close taxo-
<br />nomic relationship between populations inhabiting those rivers.
<br />
<br />MATERIALS AND METHODS. Seventy-four specimens of Rhinichthys osculus
<br />obtained in 14 callections from the Moapa River were examined to determine their
<br />morphometry and meristics. Counts and measurements employed were those used
<br />far R. osculus by Hubbs et al. (1974). Precision dial calipers permitted all measure-
<br />ments to be taken to the nearest 0.1 mm. Each measurement was taken during an
<br />uninterrupted time period to insure uniformity in results. Fish with damaged fins
<br />were disregarded for apprapriate measurements. Meristic data were gathered under
<br />proper magnification and illumination, usually with a 40X dissecting microscope.
<br />Counts of vertebrae were taken from radiagraphs provided by Dr. Robert R. Miller.
<br />In all, 18 marphometric measurements were taken and 16 meristic characters were
<br />counted on each of the 74 fish. For each measurement, a mean (x), range, standard
<br />deviation (SD), and number of fish measured (n) are reported. Holotype and para-
<br />types were borrowed fram Arizona State University (ASU) and the University of
<br />Nevada, Las Vegas (UNLV). Specimens presently are depasited at the University
<br />of Nevada, Las Vegas, Museum af Fishes and at the Museum of Natural History of
<br />Tulane University (TU).
<br />
<br />Rhinichthys osculus moapae, Maapa River speckled dace, n. ssp.
<br />
<br />HOLOTYPE. TU 103139, 76.5 mm, Maapa River at Anderson Dairy Fann.
<br />
<br />PARATYPES. All specimens were collected from Maapa River, Clark County,
<br />Nevada. Anderson Dairy Farm, 7 specimens (halotype; TU-103140, 3 specimens,
<br />49.2-64.3 mm in standard length; ASU-5481, 1, 59.5; ASU-5493, 1, 67.3; ASU-
<br />5500, 1, 45.9); Interstate Highway 15, 2 (ASU-5495, 1, 60.2; ASU-5496, 1, 50.0);
<br />Lawhead Dam, 44 (ASU-5497, 10,47.6-54.2; ASU-5498, 29, 45.7-55.1; TU-l03141,
<br />5,47.6-53.4); Pedersen's Warm Springs, 15 (ASU-5499, 15,43.6-53.4); Taylor (=
<br />Home) Ranch, 6 (ASU-5501, 1, 52.4; ASU.5502, 4, 49.4--57.9; ASU-5503, 1,42.4).
<br />
<br />DESCRIPTION. A large Rhinichthys osculus with slender, torped:J-shaped body;
<br />greatest body depth 214 (thousandths) in SL; smut length 82 in SL; head length
<br />257 in SL; head depth 146 in SL; caudal peduncle notably long and slender; caudal
<br />peduncle depth 109 in SL; dorsal and anal fins distinctively large and falcate;
<br />depressed darsal fin length 258 in SL; caudal fin expansive and deeply forked;
<br />caudal fin length 271 in SL; dorsal rays 8, rarely 9; ~Lrays 6-8, typically 7;
<br />caudal rays 18-21, typically 19; vertebrae 36-41; gill rakers typically 7; lateral-
<br />line scales 53-72; tW:J barbels present; premaxillary frenum present; caloration
<br />silvery-blue dorsally and silver ventrally; silver-blue lateral stripe usually present;
<br />dark speckles absent an many specimens.
<br />
<br />ETYMOLOGY. The subspecific epithet moapae, af Maapa, refers ta endemism
<br />of the populatian in the Moapa River.
<br />
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