| 1a |
Legs thick, shorter than (or at least not conspicuously longer
than) the combined length of the proboscis
and trunk; outline of the animal as a whole oval or elliptical; without
chelicerae
or pedipalps; without
conspicuous spiny projections |
2 |
| 1b |
Legs usually much longer than the combined length of the proboscis
and trunk (pycnogonids of this type are usually awkward and gangly, but
sometimes are fairly compact); outline of the animal as a whole approximately
circular; with either chelicerae
or pedipalps, or
both; often spiny or setose |
3 |
| 2a |
Color uniform (ivory to pink); height of dorsal tubercles,
when these are present, not greater than their basal diameter |
Pycnogonum stearnsi |
| 2b |
Color not uniform (generally light brown with dark lines, or with clear
areas between dark patches); height of dorsal tubercles
greater than their basal diameter |
Pycnogonum rickettsi |
| 3a |
With both chelicerae
and pedipalps (the
pedipalps
are conspicuous and have several articles); chelicerae
either with functional chelae
or with chelae reduced
to knobs (juveniles of some species, however, have chelae
that are lost as the animals mature); ovigerous
legs usually present in both sexes and conspicuous |
4 |
| 3b |
With chelicerae,
but without pedipalps;
chelicerae
with
chelae and conspicuous;
ovigerous
legs reduced or entirely absent in females |
17 |
| 4a |
Chelicerae
with 2 basal articles; small chelae
sometimes present (the chelae
may, however, be reduced to nonfunctional knobs) |
5 |
| 4b |
Chelicerae
with a single basal article (scape); with a chela
or a knoblike second article (or the entire appendage may be reduced to
a knob or to an elongate, tuberclelike
structure) |
7 |
| 5a |
|
|
| 5b |
|
|
| 6a |
|
|
| 6b |
|
|
| 7a |
Chelicerae
reduced to knobs or tubercles |
8 |
| 7b |
Chelicerae
consisting of a basal article (scape) and either a well developed terminal
chela
that extends beyond the proboscis
or with a knoblike article (if functional chelae
are present in sub-adults, these do not extend beyond the proboscis) |
11 |
| 8a |
Each chelicera
consisting of an easily recognized, papillate
process; a gangly species with rather long and slender legs, these often
with brownish purple bands; pedipalps
with 9 articles |
Ammothea hilgendorfi |
| 8b |
Chelicerae
small and difficult to see; animal rather compact; pedipalps
with 6 or fewer articles |
9 |
| 9a |
Body covered with short setae,
thus appearing hairy; associated with the alcyonacean Gersemia rubriformis |
Tanystylum anthomasti |
| 9b |
Body not covered with short setae
(it may, however, have sparse spines); not normally associated with Gersemia |
10 |
| 10a |
Proboscis about
twide as long as its diameter at the base, rounded at the tip, trunk very
compact, the lateral projections indistinct |
Tanystylum occidentalis |
| 10b |
Proboscis at
least 3 times as long as its diameter at the base, tapering to a blunt,
subconical tip; trunk not so compact as in T.
occidentalis, the lateral projections touching, but distinct |
Tanystylum sp. |
| 11a |
Chelicerae conspicuous, chelate, extending beyond the proboscis; pedipalps
slender, with 5 articles; total diameeter, when the legs are outstretched,
sometimes exceeding 5 cm; usually subtidal |
12 |
| 11b |
Chelicerae usually reduced to knobs in the adult, but if chelae persist,
the chelicerae are shorter than the proboscis; pedipalps with 8 articles;
total diameter less than 2 cm; includes some intertidal species |
13 |
| 12a |
|
|
| 12b |
|
|
| 13a |
Adults not chelate |
14 |
| 13b |
Adults chelate, the dactyl and fixed finger arcuate (a seasonal parasite
of mussels in central California; found at least as far north as Boiler
Bay, Oregon, but the habitat on the Oregon coast is not known) |
Achelia chelata |
| 14a |
Dorsodistal edges of first coxal articles with fingerlike projections
or short outgrowths |
15 |
| 14b |
Dorsodistal edges of first coxal articles without fingerlike projections
or short outgrowths (there may, however, be low knobs or wartlike eminences
on the lateral projections of the trunk) |
Achelia latifrons |
| 15a |
|
|
| 15b |
|
|
| 16a |
|
|
| 16b |
|
|
| 17a |
Lateral projections very close together; auxiliary claws minute and
inconspicuous; legs slender (intestine bright green, its branches clearly
visible in the legs; eye tubercle
at least twice as high as broad) |
Anoplodactylus viridintestinalis |
| 17b |
Lateral projections separated by at least half their diameter; auxialiary
claws small but well developed; legs stout |
Phoxichilidium femoratum |