Eucteniza | |
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Eucteniza relata, female (top) and male | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Chelicerata |
Class: | Arachnida |
Order: | Araneae |
Infraorder: | Mygalomorphae |
Family: | Euctenizidae |
Genus: |
Eucteniza Ausserer, 1875 |
Type species | |
Eucteniza mexicana Ausserer, 1875 |
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Diversity | |
14 species | |
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Eucteniza species in North America | |
Synonyms | |
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Eucteniza ( /juːktəˈnaɪzə/ yook-tə-NY-zə) is a genus of trapdoor spiders in the family Euctenizidae containing at least 14 species occurring in Mexico and the southern United States. Species are distinguished by a softened rear portion of the carapace, and males possess large spines on the first two pairs of walking legs that are used to hold females during mating. Like other trapdoor spiders they create burrows with a hinged lid, from which they await passing insects and other arthropods to prey upon. Many species are known from only one or two localities, or from only male specimens. More species are expected to be discovered. Eucteniza is closely related to spiders of the genera Entychides and Neoapachella.
Members of Eucteniza reach up to 27.5 mm (1.08 in) in body length (not including the legs), which is relatively large to very large among spiders. The cephalothorax (the anterior body segment bearing the eyes, mouthparts, and legs) is oval, slightly longer than wide, and slopes considerably towards the rear when viewed from the side. The rear third of the carapace (the upper surface of the cephalothorax) is relatively soft, and is distinctly lighter in coloration. The carapace is often devoid of hairs, and in some species fringed with black bristles. The eight eyes are not elevated and are arranged in two rows in a rectangular area: the hind row is recurved, or slightly curved upwards (as in a bowl or shallow U), while the anterior row is slightly procurved (slightly curved downwards, as in an inverted bowl). Eucteniza spiders are colored in various shades of brown, with males generally appearing a dark reddish brown. The jaws (chelicerae) are dark brown. The abdomen sometimes has a dark brown blotch on the upper surface. Measurements of most species only refer to the cephalothorax, which is less variable than the abdomen: recorded cephalothorax lengths range from 3.5 mm (0.14 in) in E. huasteca to 11.5 mm (0.45 in) in E. relata.