Morphometric Comparison of Pupfish Populations, Cyprinodon nevadensis, at Shoshone and Tecopa, California

Abstract

Shoshone Spring by Taylor et al. (1988). Shoshone Spring is at the northern-most head of the pluvial Amargosa River in the Death Valley system. It is tributary to the Amargosa River approximately 21 km N (upstream) of Tecopa, Inyo Co., California. The elevation of Shoshone Spring is 518 m, dropping to approximately 487 m at the outflow creek. Elevation of Tecopa Bore is approximately 390 m, an elevational drop of approximately 128 m. The elevation of the Amargosa River decreases significantly as it enters and flows through the Amargosa Canyon south of Tecopa. During periods of heavy rainfall and flash flooding, the area may briefly have fastmoving water flowing downstream throughout the entire system. During his 1939 visit to Shoshone and Tecopa, Miller (1948) found no water in the Amargosa River at Shoshone and found two permanent flows occurring in the lower Amargosa River. One began shortly above Tecopa and continued through the Amargosa Canyon about 11 km to Sperry. The other flow was round in Death Valley, northwest of Saratoga Springs and approximately 32 km downstream from Sperry. Taylor et al. (1988) found water in the Amargosa River at Shoshone, although approximately 11 km of the 21 km of streambed be w en Shoshone and tecopa were dry. In a meristic analysis, Taylor et al. (1988) concluded that the rediscovered population at Shoshone most closely resembled C. n. shoshone as described by Miller (1948). The Shoshone population resembled C. n. shoshone and differed from the Tecopa popultion by having lower mean numbers of pelvic, dorsal, and caudal fin rays (Taylor et al., 1988). In this paper we present a morphometric analysis as a supplement to the meristic data reported by Taylor et al. (1988) for C. n. shoshone. We compare the results with similar data for C. n. amargosae from Tecopa Bore. We also compare our results for the two subspecies with those presented by Miller (1948). Sixty specimens from both Shoshone and Tecopa Bore were collected with seines, traps, and dipnets on 31 July 1986 (Taylor et al., 1988). All specimens were cataloged (catalog numbers F-1957; F-1959) at the Marjorie Barrick Museum of Natural History, University of Nevada, Las Vegas. Following Miller (1948), each specimen was characterized for head width, body width, caudal peduncle length, depressed dorsal fin length, depressed anal fin length, pelvic-fin length, and snout length. The Shoshone population differed from the Tecopa population by having smaller means for head width, body width, and pelvic fin length in