| 1a |
With 12 pairs of elytra |
Lepidonotus squamatus |
| 1b |
With at least 15 pairs (rarely 13 or 14 pairs) of elytra |
2 |
| 2a |
With 15 pairs (rarely 13 or 14 pairs) of elytra |
3 |
| 2b |
With at least 18 pairs of elytra |
23 |
| 3a |
With more than 50 segments; elytra
restricted to the anterior and middle regions of the body, at least 18
of the posterior segments not covered by them |
4 |
| 3b |
With fewer than 50 segments; elytra
covering nearly all segments |
6 |
| 4a |
|
|
| 4b |
|
|
| 5a |
|
|
| 5b |
|
|
| 6a |
At least some of the neurosetae
bifid at the tip (the
2 teeth are not equal, however) |
7 |
| 6b |
None of the neurosetaebifid
at the tip |
12 |
| 7a |
Notosetae thicker
than the neurosetae |
8 |
| 7b |
Notosetae about
the same thickness as the neurosetae |
Tenonia priops |
| 8a |
Anterior pair of eyes (on the dorsolateral surfaces of the prostomium)
not visible from the dorsal side (they are covered by outgrowths of the
prostomium)(photo)(free-living
in various habitats, and also commensal
with other polychaetes) |
Harmothoe imbricata |
| 8b |
Anterior pair of eyes visible from the dorsal side (not covered by
outgrowths of the prostomium) |
9 |
| 9a |
|
|
| 9b |
|
|
| 10a |
|
|
| 10b |
|
|
| 11a |
|
|
| 11b |
|
|
| 12a |
|
|
| 12b |
|
|
| 13a |
|
|
| 13b |
|
|
| 14a |
|
|
| 14b |
|
|
| 15a |
|
|
| 15b |
|
|
| 16a |
|
|
| 16b |
|
|
| 17a |
|
|
| 17b |
|
|
| 18a |
|
|
| 18b |
|
|
| 19a |
|
|
| 19b |
|
|
| 20a |
|
|
| 20b |
|
|
| 21a |
|
|
| 21b |
|
|
| 22a |
|
|
| 22b |
|
|
| 23a |
With 18 pairs (rarely 19 pairs) of elytra
(free-living or commensal,
usually with other polychaetes) |
Halosydna brevisetosa |
| 23b |
With more than 18 pairs of elytra |
24 |
| 24a |
Elytra on every
segment posterior to segment 38; dorsal nuchal
fold prominent and covering part of the prostomium |
Hololepida magna |
| 24b |
Elytra not on every
segment posterior to segment 38; without a prominent nuchal
fold |
25 |
| 25a |
Lateral prostomial
antennae inserted on the edge of the prostomium;
notopodia
abortive, with an acicula
but without other setae |
26 |
| 25b |
Lateral prostomial
antennae inserted slightly ventral to the edge of the prostomium;
notosetae
present, though not necessarily on all notopodia,
and sometimes few in number |
27 |
| 26a |
|
|
| 26b |
|
|
| 27a |
Elytra on segments
2, 4, 5, then every other segment to 23, 26, 30, 32, 35; following segment
35, the arrangement of elytra
is irregular, because they are not in sequence and not always in pairs;
notosetae
numerous, with pointed tips (commensal with the terebellid polychaetes
Thelepus
crispusand Neoamphitrite robusta, perhaps others) |
Polyeunoa tuta |
| 27b |
Elytra on segments
2, 4, 5, then every other segment to 23, 26, 29, then every other segment
to the end of the body; relatively few segments near the posterior end
have unpaired elytra;
notosetae
few, with rather blunt, indistinctly bifid
tips, or absent |
28 |
| 28a |
Margins of elytra
extensively ruffled or folded (commensal
with various sea stars) |
Arctonoe fragilis |
| 28b |
Margins of elytra
smooth or only slightly wavy |
29 |
| 29a |
Neurosetae (except
on segment 2) of 2 types: those above the acicula
slender and with blunt, bifid
tips, those below the acicula
stouter and with falcate,
pointed tips; with a band of dark pigment extending across segments 7 and
8 (commensal with
a wide variety of invertebrates, including sea stars, terebellid polychaetes,
gastropods [especially Diodora
aspera], and Cryptochiton
stelleri) |
Arctonoe vittata |
| 29b |
Neurosetae essentially
of 1 type: falcate
and with pointed tips; without a dark band of pigment extending across
segments 7 and 8 (commensal
with a variety of invertebrates, including sea stars, the sea cucumber
Parastichopus
californicus, Cryptochiton
stelleri, and terebellid polychaetes) |
Arctonoe pulchra |