Editorial Type:
Article Category: Research Article
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Online Publication Date: 17 Dec 2010

Sexual Dimorphism, Diet, Reproduction, and Their Geographic Variation in Sympatric Psammophiids, Psammophis crucifer and Psammophylax rhombeatus rhombeatus, from Southern Africa

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Page Range: 578 – 590
DOI: 10.1643/CE-10-018
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Abstract

The examination of museum specimens allows for the robust analysis of ecological and life history traits in snakes, and can be especially useful in revealing characteristics often undetected in geographically limited studies. We measured and dissected 242 Psammophis crucifer and 358 Psammophylax r. rhombeatus, two widespread and abundant psammophiids from southern Africa, and quantified sexual size dimorphism (SSD), feeding habits, and geographic variation of these traits throughout their range. Female P. crucifer and male P. r. rhombeatus were larger than the opposite sex, both species were saurophagous but P. r. rhombeatus incorporated a wider range of taxa, and the reproductive biologies of both species were consistent with those of their congeners. We also examined intraspecific variation in these ecological traits based on differences in annual and seasonal rainfall patterns across their broad distribution. In large part the ecology of these temperate-inhabiting snakes mirrors that of other psammophiids and convergent whipsnakes.

Copyright: 2010 by the American Society of Ichthyologists and Herpetologists
Fig. 1
Fig. 1

Psammophis crucifer and Psammophylax r. rhombeatus distribution (circles and triangles) in Southern Africa used for this study. Many localities correspond to multiple specimens. Circles and triangles denote mesic and xeric zones, respectively. Shaded portion represents winter rainfall zone and non-shaded portion summer rainfall zone.


Fig. 2
Fig. 2

Number of P. crucifer (A) and P. r. rhombeatus (B) specimens collected by month. Specimens for each species were divided based on winter rainfall zone (W) and summer rainfall zone (S) for each month. Juveniles (uniform dark gray) were pooled across gender. Adult females (black patterns) were deemed sexually active based on criteria outlined in Materials and Methods. Adult males of both species (gray patterns) always had turgid, swollen testes at the time of collection, but presence of sperm in the efferent ducts varied seasonally.


Contributor Notes

Department of Biology, Villanova University, 800 Lancaster Avenue, Villanova, Pennsylvania 19085; E-mail: (AMC) amcottone@gmail.com; and (AB) aaron.bauer@villanova.edu. Send reprint requests to AMC.

Associate Editor: J. D. Litzgus.

Received: 06 Feb 2010
Accepted: 25 Jun 2010
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