Mygalomorph Trapdoor Spider, Kempner, TX: 111208, pg 7

This photo shows a close-up view of this spider's distal chelicerae, with the fangs extended (and out of focus) so that the cheliceral furrows and their related denticles, and a rastellum ("little rake," a rake-like structure near the cheliceral fang base, present in some mygalomorphae) can be examined. Ubick et al. (2005) p. 270, shows the rastellum as a patch of short spines, which may or may not be present in this specimen, but the tuft of spines near the top of the photo, on the distal extremity of the chelicerae, form what is described in a key published by a major museum as a rastellum, so, at least by that latter definition this specimen is positive for that anatomical feature. Absent a rastellum, we must rule out the Ctenizidae, despite the presence of a deep, procurved thoracic furrow in this specimen, and the Cyrtaucheniidae as well. I am not convinced of the above definition, yet it seems likely this specimen is possessed of a rastellum. This suggests the need for a more thorough analysis of the chelicerae. Continuing on, note that denticles and teeth appear to be of similar size on both margins of the cheliceral furrow. The morphology of the cheliceral furrow is a significant marker for certain families, including all of the Ctenizidae but--within the Cyrtaucheniidae--only the two North American species represented in the genus Eucteniza, both of found mostly in Texas. NEXT PAGE ---- PAGE MENU:  1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 *

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