| 1a |
Peristomium
with a large, papillated,
proboscislike
extension |
Artacama conifera |
| 1b |
Peristomium
without a proboscislike
extension |
2 |
| 2a |
Uncini,
if present
in the thoracic
region,
in a single row (but this row may form a loop) |
3 |
| 2b |
Uncini
in some thoracic
segments (especially those in the posterior half of the thorax)
in a double row, interlocking in much the same way as the teeth of a
zipper |
11 |
| 3a |
With 2 or 3 pairs of slender, unbranched gills |
4 |
| 3b |
Without gills |
9 |
| 4a |
Capillary
notosetae
beginning
on the first gill-bearing segment |
Streblosoma bairdi |
| 4b |
Capillary
notosetae
beginning
on the second or third gill-bearing segment |
5 |
| 5a |
With 2 pairs of gills (photo) |
6 |
| 5b |
With 3 pairs of gills (photo) |
7 |
| 6a |
First 4 thoracic segments similar to succeeding
thoracic segments in
that they are glandular ventrally and laterally |
Thelepus cincinnatus |
| 6b |
First 4 thoracic segments different from succeeding
thoracic segments
in that they are completely encircled by glandular tissue |
Thelepus hamatus |
| 7a |
Rows of uncini,
beginning with segment 8, curved to form a nearly closed ellipse |
Thelepus
crispus |
| 7b |
Rows of uncini,
on all segments that have them, nearly straight |
8 |
| 8a |
Notosetae
absent
from about the last 40 segments; gill filaments not obviously coiled |
Thelepus
setosus |
| 8b |
Notosetae
absent
from only about the last 10 segments; gill filaments usually coiled |
Thelepus
japonicus |
| 9a |
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| 9b |
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| 10a |
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| 10b |
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| 11a |
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| 11b |
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| 12a |
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| 12b |
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| 13a |
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| 13b |
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| 14a |
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| 14b |
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| 15a |
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| 15b |
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| 16a |
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| 16b |
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| 17a |
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| 17b |
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| 18a |
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| 18b |
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| 19a |
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| 19b |
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| 20a |
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| 20b |
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| 21a |
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| 21b |
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| 22a |
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| 22b |
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| 23a |
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| 23b |
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| 24a |
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| 24b |
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| 25a |
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| 25b |
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| 26a |
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| 26b |
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| 27a |
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| 27b |
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| 28a |
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| 28b |
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| 29a |
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| 29b |
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| 30a |
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| 30b |
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| 31a |
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| 31b |
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| 32a |
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| 32b |
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| 33a |
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| 33b |
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| 34a |
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| 34b |
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| 35a |
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| 35b |
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