Here is a crangonid species captured from the Sea of Okhotsk off Kamchatka,
NW Pacific (not in key):
Argis
ochotensis
| 1a |
Rostrum
more than half as long as the rest of the carapace;
with only 4 pairs of legs |
Paracrangon echinata |
| 1b |
Rostrum,
if present, less than half as long as the rest of the carapace
(photo); with 5 pairs of
legs |
2 |
| 2a |
Dactyl
of leg 5 broad and flattened; eyestalks parallel and shielded by a hood
that consists of the antennal spines, postorbital spines, and rostrum |
3 |
| 2b |
Dactyl
of leg 5 not broad and flattened (photo);
eyestalks not parallel and not shielded by a hood consisting of spines |
7 |
| 3a |
Carapace
with 2 median spines in addition to the spine that forms the rostrum |
4 |
| 3b |
Carapace
with 3 or 4 median spines in addition to the spine that forms the rostrum |
5 |
| 4a |
Longitudinal dorsal ridges (carinae)
on abdominal segment 6 extended beyond the posterior edge of the segment
as spines |
Argis dentata |
| 4b |
Longitudinal dorsal ridges on abdominal segment 6 not extended beyond
the posterior edge of the segment as spines |
Argis lar |
| 5a |
Longitudinal dorsal ridges (carinae)
on abdominal segment 6 extended beyond the posterior edge of the segment
as spines |
Argis alaskensis |
| 5b |
Longitudinal dorsal ridges on abdominal segment 6 not extended beyond
the posterior edge of the segment as spines |
6 |
| 6a |
Abdominal segments 1-4 with a longitudinal dorsal ridge; pleuron
of abdominal segment 4 with a small posteroventral spine |
Argis crassa |
| 6b |
Abdominal segments 1-4 without a longitudinal dorsal ridge; pleuron
of abdominal segment 4 without a posteroventral spine |
Argis levior |
| 7a |
Carapace
with a median dorsal spine or spines (photo) |
8 |
| 7b |
Carapace
without median spines |
Lissocrangon stylirostris |
| 8a |
Submedian spines present on carapace |
9 |
| 8b |
Submedian spines absent on carapace |
13 |
| 9a |
Carapace
with 2 submedian spines on both sides |
Mesocrangon munitella |
| 9b |
Carapace
with 1 submedian spine on both sides (photo) |
10 |
| 10a |
Pleura
of abdominal segments 1-3 with ventrally directed spines |
Metacrangon spinosissima |
| 10b |
Pleura
of abdominal segments 1-3 without ventrally directed spines |
11 |
| 11a |
Anterior median carapace spine extending beyond the bases of the orbits
of the eyes, and larger than the posterior median carapace
spine |
Metacrangon acclivis |
| 11b |
Anterior median carapace spine not extending beyond the bases of the
orbits
of the eyes, and not larger than the posterior median carapace
spine (photo) |
12 |
| 12a |
Abdominal segments 3-5 with a prominent longitudinal dorsal ridge (carina);
spine of scale of antenna 2 reaching to or beyond the tip of the lamella |
Metacrangon variabilis |
| 12b |
Abdominal segments 3-5 without a prominent longitudinal dorsal ridge;
tip of the lamella
of the scale of antenna 2 reaching beyond the spine (photo) |
Metacrangon munita |
| 13a |
Carapace
obviously sculptured |
14 |
| 13b |
Carapace
smooth |
15 |
| 14a |
Carapace
with 1 or 2 median spines; outer margin of scale of antenna 2 (antennal
scale) concave |
Rhynocrangon alata |
| 14b |
Carapace
with 3 or 4 median spines; outer margin of scale of antenna 2 (antennal
scale) convex |
Sclerocrangon boreas |
| 15a |
Carapace
with 2 median spines |
16 |
| 15b |
Carapace
with 1 median spine (photo) |
18 |
| 16a |
Rostrum
ascending at an angle of about 45 degrees and extending beyond the eyes;
rostrum,
in adult, with a large ventral expansion |
Neocrangon resima |
| 16b |
Rostrum
ascending at an angle of 30 degrees or less and not extending beyond the
eyes; rostrum
without a ventral expansion |
17 |
| 17a |
Tip of rostrum
rounded; eyes not contiguous |
Neocrangon communis |
| 17b |
Tip of rostrum
acute; eyes large and contiguous |
Neocrangon abyssorum |
| 18a |
Dorsal surface of abdominal segment 6 with 2 prominent lateral ridges
(carinae) |
Crangon dalli |
| 18b |
Dorsal surface of abdominal segment 6 without londitudinal ridges (photo) |
19 |
| 19a |
Abdominal segment 5 with a spine on the upper posterolateral margin
of both sides |
20 |
| 19b |
Abdominal segment 5 without spines on the upper posterolateral margins
(photo) |
21 |
| 20a |
Dactyl
of leg 1 reaching the base of the fixed finger when the chela
is closed; propodus
of leg 1 of male 4.5 times as long as wide |
Crangon franciscorum
subspecies franciscorum |
| 20b |
Dactyl
of leg 1 crossing the base of the fixed finger when the chela
is closed; propodus
of leg 1 of male 5.5 times as long as wide |
Crangon franciscorum
subspecies angustimana |
| 21a |
Ventral surface of abdominal segment 6 with a median groove (sulcus)
(photo) |
22 |
| 21b |
Ventral surface of abdominal segment 6 without a median groove |
Crangon alba |
| 22a |
Flagella
of antenna 1 equal in length; scale
of antenna 2 (antennal
scale) not more than twice as long as wide (not known to occur north
of California) |
Crangon handi |
| 22b |
Inner
flagellum of antenna 1 longer than the outer flagellum; scale
of antenna 2 more than twice as long as wide (photo) |
23 |
| 23a |
Spine
of scale of antenna 2 (antennal
scale) extending beyond the tip of the lamella,
which is narrow (photo);
scale
of antenna 2 as long as, or longer than, the telson |
Crangon alaskensis |
| 23b |
Spine
of scale
of antenna 2 reached or exceeded by the tip of the lamella,
which is a rounded lobe; scale
of antenna 2 shorter than the telson |
Crangon nigricauda |