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Diel Activity in Sympatric Populations of the Scorpions Centruroides sculpturatus (Buthidae) and Diplocentrus spitzeri (Diplocentridae)
C. S. Crawford and R. C. Krehoff
The Journal of Arachnology
Vol. 2, No. 3 (Sep., 1974), pp. 195-204
Published by: American Arachnological Society
Stable URL: http://www.jstor.org/stable/3704933
Page Count: 10
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Field observations of sympatric Centuroides sculpturatus and Diplocentrus spitzeri scorpions in the Peloncillo Mountains in New Mexico revealed that during the warmer months nocturnal extra-rock surface activity was relatively great in the former species. In contrast, D. spitzeri tended to remain beneath rocks near the openings of its burrows. During the day C. sculpturatus also used the rocks as shelter, clinging to the underside. Actograph studies of both species showed them both to have nocturnal activity when imposed photoperiod was the only variable; however, only C. spitzeri displayed an endogenous circadian rhythm in constant darkness. Rooftop observations of D. spitzeri confined to containers, each with soil and a rock for shelter, indicated that under poor shelter conditions extra-rock nocturnal activity is common for early instars through adults. In another rooftop study D. spitzeri adults exhibited random choice of available rock shelter. It was concluded that different spatial and temporal strategies may make possible avoidance of competition between these two species.
The Journal of Arachnology © 1974 American Arachnological Society