| 1a |
Width of carapace
less than 1.5 times the length |
2 |
| 1b |
Width of carapace
at least 1.5 times the length |
6 |
| 2a |
Carapace
calcified and rather firm (may be fairly soft in some gravid females) |
3 |
| 2b |
Carapace
soft |
4 |
| 3a |
Hairs on legs 3 and 4 featherlike and much longer than
those on the
other legs (this feature is less pronounced on gravid females); dactyls
of walking legs decidedly curved; generally living in the mantle cavity
of bivalve molluscs (Modiolus
modiolus, Mytilus
californianus, M. edulis (M.
trossulus), Tresus
capax, Mya
arenaria, Astarte compacta, Cyclocardia
ventricosa,
Crenella
decussata, Kellia suborbicularis), or
sometimes Nuttalia
obscurata, but sometimes free-living |
mature males and females
of Fabia
subquadrata |
| 3b |
Hairs on legs 3 and 4 not noticeably longer than those
on the other
legs; dactyls
of walking legs only slightly curved; living in burrows of
Callianassa
(Neotrypaea)
and Upogebia |
Scleroplax
granulata |
| 4a |
Dorsal surface of the carapace
with a longitudinal groove extending posteriorly from the orbit
of each eye; dactyls
of walking legs decidedly curved (in the mantle cavity of various
bivalve
molluscs; see choice 3a) |
subadults and ovigerous
females of Fabia
subquadrata |
| 4b |
Dorsal surface of the carapace
without a longitudinal groove extending posteriorly from the orbit
of each eye; dactyls
of walking legs nearly straight |
5 |
| 5a |
|
|
| 5b |
|
|
| 6a |
Corneous
tips of dactyls
of legs 2-5 decidedly curved |
7 |
| 6b |
Corneous
tips of dactyls
of legs 2-5 nearly straight |
8 |
| 7a |
Outer margin of eye orbits
(in anterior view) rounded; male with a gap between the dactyl
and fixed finger of the chela,
but female without this gap (mature individuals, including gravid
females, in the bivalve
Tresus
capax; immature individuals in many bivalves, and
sometimes in
hosts other than bivalves) |
Pinnixa
faba |
| 7b |
Outer margin of eye orbits
(in anterior view) somewhat acute;
both sexes with a gape between the dactyl
and fixed finger of the chela
(mature individuals in the bivalve Tresus
capax; immature individuals in many bivalves, and
sometimes in
hosts other than bivalves) |
|
| 8a |
Propodus
of
legs 3-5 longer than the dactyl
(it is also about 3 times as wide as the dactyl)
(in tubes of terebellid
polychaetes, including Eupolymnia heterobranchia) |
Pinnixa
tubicola |
| 8b |
Propodus
of legs 3-5 not longer than the dactyl
(and not usually more than twice as wide as the dactyl,
except in Pinnixa schmitti) |
9 |
| 9a |
Inner margin of dactyl
of chela
with a distinct tooth; carapace
about twice as wide as long, rounded laterally (in tubes of the lugworm
genus Abarenicola) |
Pinnixa
eburna |
| 9b |
Inner margin of dactyl
of chela
without a distinct tooth; carapace
more than twice as wide as long, pointed laterally |
10 |
| 10a |
|
|
| 10b |
|
|