| CPIE Project | Page A10 |
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BEETLES Order Coleoptera. When completed, the following key will cover both adult and immature stages. Adult aquatic beetles are air-breathing. The dytiscid pictured here is obtaining air through the posterior tip of its abdomen, which is seen just breaking the surface as the animal hangs head down in the water. The hind legs are adapted for swimming: more or less flattened and heavily fringed with hairs.
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| 131a | Antennae long and filiform (narrow, filament-like); maxillary palps short. In the water, frequently seen hanging head downward at the surface, or swimming by moving both hind legs together ~ Family DYTISCIDAE |
[132] | |||
| 131b | Antennae short and club-shaped; maxillary palps as long or longer than the antennae. In the water air carried in a film on the ventral surface; swimming by moving hind legs alternately. Water scavenger beetles ~ Family HYDROPHILIDAE |
[144] | |||
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| 132a | Adult beetle about 1 cm long or slightly more. Males (only) with as many as 30 sucker discs on the underside of fore and middle tarsi Rhantus pacificus Boisdduval
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| 132b | Adults smaller, less than 0.5 cm long and closer to 0.25 cm. Males with far fewer sucker discs on tarsi | [133] | |||
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| 144a | (131) | Underside of thorax having a sternal keel, projecting backwards as a long spine. Moderately large, 8-9.5 mmm long | [145] | ||
| 144b | Underside of thorax may have a sternal process, but this not a continuous keel terminating in backward-pointing spine; OR posterior segment only projecting as a short spine | [146] | |||
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| 145a | (144) | Pronotum and elytra uniformly black with a metalic hue Tropisternus salsamentus Fall
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| 145b | Pronotum and elytra metalic black with yellow lateral margins Tropisternus lateralis humeralis Motschulsky
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| 146a | (144) | Larger species, typically greater than 7.5 mm long. Elytra with 10 regular series of tiny punctures | [147] | ||
| 146b | Smaller, less than 8 mm long. Elytra with only sutural stria posteriorly, otherwise without striae or lines of punctures | [148] | |||
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| 147a | (146) | Elytra with numerouis punctures forming distinct, well-defined striations (impressed lines). Endemic Limnoxenus nesiticus (Sharp)
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| 147b | Elytra punctures not forming distinct striae (lines) except along posterior edge of suture. Endemic Limnoxenus semicylindricus (Eschscholtz)
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| 148a | (146) | Middle segment of thorax with a sharp keel along midline of underside. First segment of middle and posterior tarsi much shorter than second segment. { Color yellowish to yellowish brown with a black head and 3-4.1 mm long. Enochrus sayi Gundersen
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| 148b | Middle and posterior segments of thorax with convex processes. First segment of middle and posterior tarsi at least as long as second segment. { Color of elytra mostly black, except posterioor quarter yellowish red, 4-6.5 mm long. | [149] | |||
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| 149a | (148) | Elytra entirely black. Beetle 5.5-6.5 mm long. Indigenous(?) Coelostoma fabricii (Montrouzie)
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| 149b | Elytra black except at posterior end, which is yellowish red in color. Beetle 4.0-4.7 mm long. This species may not be established (Hansen, 1995) Coelostoma segne Balfour-Browne
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| © 2009 AECOS, Inc. [FILE: invert8.html] | Arthropods, Insects |
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