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Sw Key To Vasos Taxa


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Sw Key To Vasos Taxa

  1. 1. StreamWatch Key to Virginia SOS Taxa Groups – photo slideshow<br />To download the key, go to<br />Photo research and compilation by StreamWatch volunteer Bob Henricks.<br />
  2. 2. 1a – Organism has sectioned, jointed legs. (2)<br />Be sure to look carefully underneath the body. Be aware that stubby, fleshy prolegs without joints are not “sectioned, jointed legs.”<br /><br /><br /><br />
  3. 3. 1b – No sectioned, jointed legs. (5)<br /><br /><br /><br />
  4. 4. 2a – More than 3 pairs of jointed legs. (3) <br /><br />
  5. 5. 2b –3 pairs of jointed legs. (13) <br />
  6. 6. 3a – Shrimp-like or lobster-like and can move quickly in water. (4)<br />Prod the organism gently to test its movement.<br /><br />
  7. 7. 3b – Body is wider than it is tall. Organism does not swim or rapidly propel itself through water, though it can walk well with its many legs. SOWBUGS<br /><br />
  8. 8. 4a – Fan-shaped tail. CRAYFISH<br /><br />
  9. 9. 4b – Body is taller than it is wide. No fan-shaped tail. SCUDS<br /><br />
  10. 10. 5a – Organism is inside a shell. (6) <br />5b – Not inside a shell (though possibly in a case). (9)<br /><br /><br />5a<br />
  11. 11. 6a – Shell composed of two halves that join at base to form hinge. CLAMS<br />6b – Shell not as described in 6a. (7)<br /><br />
  12. 12. 7a – Shell forms a coil. LUNGED SNAILS<br />7a<br /><br />
  13. 13. 7b – Shell forms a flattened cone. LUNGED SNAILS<br /><br />
  14. 14. 7c - Shell forms a spiral. (8)<br />ttp://<br /><br />
  15. 15. 8a – With apex up and opening down, shell opening is to the left. LUNGED SNAILS<br /><br />
  16. 16. 8b – With apex up and opening down, shell opening is to the right. GILLED SNAILS<br />8b<br /><br />
  17. 17. 9a – No distinct head composed of hardened exoskeleton material can be seen. (10)<br />Use magnification.<br />9a<br /><br /><br />
  18. 18. 9b – Organism has a distinct head. The head is composed of hardened exoskeleton material. (12). The head may be very small, so use magnification when looking for this feature.<br />9b<br /><br />
  19. 19. 10a – Body without any of the features listed in 10b. (11)<br />10b – Body with one or more of the following features: fleshy, unjointed prolegs, encircling raised ribs or welts, tentacle-like structures producing from end of body, a row of suckers on underside of body. MOST TRUE FLIES<br /><br /><br /><br />
  20. 20. 11a – Looks like an earthworm, though often skinnier. Very regular cylindrical form; no bumps or protrusions of any kind. Usually pinkish. AQUATIC WORMS<br /><br />
  21. 21. 11b – Organism appears as a small (less than 1/8”) grayish blob out of water. In water, it may resolve into flattened slug-like form with a triangular head. If intact, it may move slowly around the bottom or sides of the container in a sliding manner, like a slug sliding over the ground. FLATWORMS<br /><br />
  22. 22. 11c – Suckers on both ends of underside. LEECHES.Leeches are exceedingly rare in riffles of the Rivanna basin.<br />
  23. 23. 12a – Shaped like a bowling pin. Sometimes sticks to tweezers with invisible silk. On larger specimens (1/8 inch and over), two feather like-structures attached to head are visible with magnification. BLACKFLIES<br />12a<br />
  24. 24. 12b – Not as described in 12a or 12 c. Often very small, appearing as a short bit of thread. Often very wriggly when placed in water. MIDGES<br /><br />
  25. 25. 12c – Not as described in 12 a or 12b. Head is partially or almost completely withdrawn into thorax. Skin has tough, leathery, grainy texture. Thorax much wider than head. SOLDIER FLY; classify within MOST TRUE FLIES. The soldier fly is extremely uncommon in Rivanna basin riffles.<br /><br />
  26. 26. 13a – Lives in case constructed of sand, tiny pebbles, sticks, bits of leaves, or other detritus (although organism may have become separated from case). Abdomen is soft and grub-like. No filamentous gill tufts along underside of abdomen. CASEMAKING CADDISFLY; classify within MOST CADDISFLIES<br />13b – Not as in 13a. (14)<br /><br /><br />
  27. 27. 14a – Filamentous gill structures along entire underside of abdomen. These structures usually look like “fluff”. [Do not confuse with hellgrammite, which has elongate structures producing from side of abdomen (see 19a)]. There are also always two short tufts extending from the end of the abdomen, like short tails. COMMON NETSPINNERS<br />14b – Not as in 14a. (15)<br /><br />
  28. 28. 15a – Two or 3 long or longish tails (more than 1/4 of body length) at end of abdomen and gills attached to the side or top/side of the abdomen. Tails do not look like paddles when viewed from the side. Tails may look like feathers, but not short tufts. Swims with a porpoise-like motion. MAYFLIES<br />15A<br /><br />
  29. 29. 15b – Three tails that look like oars or paddles when viewed from the side. Spindly body with large eyes. Walks, does not swim. DAMSELFLY; classify within DRAGONFLIES AND DAMSELFLIES<br />15c – Not as in 15a or 15b. (16)<br /><br />
  30. 30. 16a – Always 2 tails. Abdomen is not soft and grub-like. No gills along sides of abdomen. Gills may be present on underside of thorax. Swims weakly with sharklike side-to-side motion. No clearly visible jaws. STONEFLIES<br /><br /><br />
  31. 31. 16b – Two tails. Long slender jaws. Strong swimmer. DIVING BEETLE; classify withinBEETLES. Uncommon in Rivanna basin riffles.<br />16c – Not as in 16a or 16b. (17)<br />
  32. 32. 17a – Long, soft abdomen (but with 3 pairs of jointed legs). Often but not always yellow-orange. No significant elongate structures coming off side of abdomen (though hairs may be visible under magnification). NON-CASEMEMAKING CADDISFLY; classify within MOST CADDISFLIES<br />17b – Not as in 17a. (18)<br /><br />
  33. 33. 18a – Body is at least four times as long as it is wide. (19)<br />18b – Body not so long and slender as described in 18a. (20)<br /><br /><br />
  34. 34. 19a – Thin elongate structures produce outward along both sides of abdomen. These structures are sometimes mistaken for legs (the creature actually has just six legs). There may also be fluffy gill structures producing from underside of abdomen. [Do not confuse with netspinning caddisflies, which have fluffy abdominal gills but no elongate structures producing outward from the side (see 14a)]. Substantial jaws are visible on large and medium-sized specimens. HELGRAMMITES and ALDERFLIES<br />
  35. 35. 19b – No elongate structures producing from side of abdomen. Often assumes comma-like shape when lying on net, sheet, or at bottom of container. Usually deep brown, almost black. Sometimes amber or pale amber. There is a cavity with a hinged lid on the underside of the end of the abdomen that houses white filamentous gills. These may be extended from cavity when the organism needs oxygen. When extended they are visible without magnification. RIFFLE BEETLE LARVA; classify within BEETLES<br /><br />
  36. 36. 20a – Legs are visible when viewed from above. (21)<br />20b – Legs and most body structures are not visible from above because they are located beneath a broad, flattened, oval-shaped structure. Often but not always copper-colored. WATER PENNY; classify within BEETLES.<br />legs. (13) <br /><br />
  37. 37. 21a – Hard wing coverings originate on thorax and extend over the entire abdomen, like a ladybug. A line is formed where they meet, and runs lengthwise along the top of the abdomen (use magnification). Usually less than 1/8” long. ADULT RIFFLE BEETLE or LONG-TOED WATER BEETLE; classify within BEETLES. <br /><br /><br />
  38. 38. 21b – No wing coverings as described in 21a. Very often longer than 1/8”, ranging up to over an inch. DRAGONFLY; classify within DRAGONFLIES AND DAMSELFLIES.<br /><br />
  39. 39. Miscellaneous:<br /> <br />Cone with hairs coming out of the wide end – BLACKFLY pupae.<br />Cylindrical membranous sack with smoothly rounded ends – pupating MOST CADDISFLY<br /><br />