GEOGRAPHIC VARIATION IN THE DWARF , PUER HOBBS (, ) 1)

BY

C. L. CHAMBERS,J. F. PAYNE and M. L. KENNEDY Department of Biology, Memphis State University, Memphis, 38152, U.S.A.

INTRODUCTION The dwarf crayfish, Hobbs, 1945, occurs in sloughs and temporary ditches from southeastern and , north into southern Missouri and along both sides of the River (Page & Burr, 1973; Hobbs, 1974; Reimer & Clark, 1974). Studies exist on the ecology (Penn, 1950 ) , life history (Penn, 1950; Black, 1966), and behavior (Penn & Fitzpatrick, 1963; Penn & Black, 1963) of this . Geographic variation in crayfish has been investigated (Penn, 1957; Marlow, 1960; Fitzpatrick, 1963, 1967); to date, no study using advanced statistical techniques has been completed. Analytical techniques have been used effectively in studies of geographic variation in other (Gillham, 1956; Sokal & Rinkel, 1963; Mason, 1964; Thomas, 1968; Moulton, 1973; Saila & Flowers, 1975; Zimmerman & Ludwig, 1975 ) . A study of geographic variation in C. puer, utilizing modern univariate and multivariate statistical techniques, therefore, seemed in order. The objectives of this study were: to analyze the distribution of morphologic variation and to determine the correlation between morphologic variation and environmental variables.

MATERIALSAND METHODS Populations of C. puer were studied from most portions of the known range (fig. 1). Specimens were collected in Shelby and Lauderdale Counties, Tennes- see, by sampling in sloughs and ditches with delta-ring dip nets. These specimens were preserved in 70% ethyl alcohol and housed in the Memphis State University Department of Biology collection. Additional specimens were also examined (see acknowledgements). Measurements were taken from 652 preserved adult specimens from 41 localities (figs. 1, 2 ) . However, all specimens were not used in the final analysis. To increase the reliability of the character means and variances, localities represented by less than three males or three females were deleted. No locality was represented by more than 49 specimens. The final raw data matrix included 583 individuals (263

1) Supported in part by a research grant-in-aid from the Sigma Xi Research Society. Reprint requests should be sent to second author. 40

Fig. 1. Unshaded area of map represents known range of Cambarellus puer Hobbs with specific localities from which specimens used in the study were studied. Localities 2, 5, 10, 13, 20, and 29 were not used because of inadequate sample size. males and 320 females) from 34 localities. All measurements were made with an ocular micrometer mounted in a Bausch and Lomb binocular dissecting scope and recorded to the nearest 0.01 mm. Morphologic characters chosen for study were selected for accuracy and repeat- ability. Measurements recorded for all specimens included: length of cephalothorax, width of cephalothorax, length of rostrum, width of rostrum, distance between postorbital spines, length of areola, vddth of areola, length of cheliped, width of palm, and length of dactyl.