Reproduction in the Speckled Rattlesnake, Crotalus mitchellii (Serpentes: Viperidae)
The speckled rattlesnake, Crotalus mitchellii (Cope, 1861) occurs from southern Nevada to the tip of Baja California and southern California to northwest and west central Arizona from sea level to around 2440 m (Stebbins 1985). It is one of 6 rattlesnake species to occur in southern California (Stebbins 1985). There are only anecdotal reports on reproduction in this species (Klauber 1936; Cunningham 1959; Brattstrom 1965; Lowe et al. 1986). Klauber (1972) provided information on sizes of egg-sets and broods. The purpose of this paper is to provide information on the seasonal ovarian and testicular cycles of C. mitchellii and to provide additional litter sizes.
A sample of 99 specimens of C. mitchellii (42 females, Mean Snout-Vent Length, SVL = 673 mm [+ or -] 82 SD, range = 520--825 mm); (57 Males, Mean SVL = 708 mm [+ or -] 137 SD, range 512--1047 mm) from Arizona, California and Nevada was examined from the herpetology collections of Arizona State University, Tempe, (ASU), the Natural History Museum of Los Angeles County (LACM) and The University of Arizona, Tucson (UAZ) (Appendix). Snakes were collected 1951-1990. Counts were made of enlarged follicles ([greater than] 10 mm length). The left testis, vas deferens and part of the left kidney were removed from males; the left ovary was removed from females for histological examination. Tissues were embedded in paraffin and cut into sections at 5 [micro]m. Slides were stained with Harris' hematoxylin followed by eosin counterstain. Testes slides were examined to determine the stage of the male cycle; ovary slides were examined for the presence of yolk deposition. Vasa deferentia were examined for sperm. Slides of k idney sexual segments were examined for secretory activity. Because some of the specimens were road-kills, not all tissues were available for histological examination due to damage or autolysis. In road-killed males, the kidneys typically underwent autolysis before the reproductive organs. Number of specimens examined by reproductive tissue were: testis = 57, vas deferens 38, kidney = 50, ovary = 42.
Testicular histology was similar to that reported by Goldberg and Parker (1975) for the colubrid snakes, Masticophis taeniatus and Pitupophis catenifer (= P. melanoleucus) and the viperid snake, Agkistrodon piscivorus reported by Johnson...
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