Crangonidae Haworth 1825

Key to species of family Crangonidae

1. Pereopod 2 absent, rostrum elevated, with 4 teeth.......................................... Paracrangon echinata

– Pereopod 2 present although sometimes very short........................................................... 2

2. Pereopod 2 much shorter than other pereopods, eye nearly without pigment............. Pontophilus gracilis occidentalis

– Pereopod 2 subequal in length to other pereopods, eye with obvious pigment...................................... 3

3. Dactyls of pereopods 4, 5 flattened, eye partially concealed by dorsal frontal margin of carapace....................... 4

– Dactyls of pereopods 4, 5 normal, stout to slender; eye not partially concealed by dorsal frontal margin of carapace........ 5

4. Carapace with 2 median teeth behind anterior margin, abdominal somites 1, 2 not carinated. South of Point Conception, California................................................................................ Argis californiensis

– Carapace with 3–4 median teeth behind anterior margin, abdominal somites 1–4 not carinated. Shelter Cove, California northward...................................................................................... Argislevior

5. Carapace with 3–4 median dorsal teeth, pleura of abdominal somites 2–5 with posteroventral spines, exoskeleton heavily sculptured........................................................................... Rhynocrangon alata

– Carapace with 0–2 median dorsal teeth, pleura of abdominal somites 5 or 6 only with posteroventral teeth if present, exoskeleton smooth or lightly sculptured.......................................................................... 6

6. Carapace with 2 median dorsal teeth...................................................................... 7

– Carapace with 1 or no median dorsal teeth................................................................ 15

7. Carapace without submedian teeth........................................................................ 8

– Carapace with submedian teeth.......................................................................... 10

8. Eye very large. Exoskeleton noticeably thin. Usually on lower continental shelf or deeper......... Neocrangon abyssorum

– Eye of moderate size. Exoskeleton not noticeably thin. Usually on continental shelf............................... 9

9. Abdominal somite 5 with broad dorsal carina............................................. Neocrangoncommunis

– Abdominal somite 5 without broad dorsal carina.............................................. Neocrangon resima

10. Second lateral carina of carapace armed with tooth slightly behind superior lateral tooth. Small, adults 25 mm or less in total length............................................................................ Mesocrangon munitella

– Second lateral carina of carapace not armed with tooth slightly behind superior lateral tooth. Usually larger than 25 mm in total length.............................................................................................. 11

11. Abdominal somites 1–4 smooth......................................................................... 12

– Abdominal somites 1–4 carinated........................................................................ 13

12. Anterior median tooth on carapace obliquely erect, larger than posterior, apex of former extending beyond orbital margin...................................................................................... Metacrangon acclivis

– Anterior median tooth on carapace not obliquely erect, not larger than posterior, apex of former well behind orbital margin....................................................................................... Metacrangon munita

13. Abdominal somites 1–3 laterally unarmed................................................ Metacrangon variabilis

– Abdominal somites 1–3 laterally armed................................................................... 14

14. Abdominal pleura 1–3 armed laterally with one tooth each..................................... Metacrangon procax

– Abdominal pleura 1–3 armed laterally with two teeth each................................ Metacrangon spinosissima

15. Carapace without median dorsal tooth.................................................. Lissocrangon stylirostris

– Carapace with median dorsal tooth....................................................................... 16

16. Abdominal somite 6 with ventral sulcus.................................................................. 17

– Abdominal somite 6 without ventral sulcus................................................................ 21

17. Hand of pereopods 1 very slender, 4 times as long as wide, flexed dactylus almost longitudinal...... Crangon franciscorum

– Hand of pereopod 1 not as slender, 3.5 times as long as wide or less, flexed dactylus not forming angle less than 45˚ with propodal margin..................................................................................... 18

18. Abdominal somite 5 not carinate. Blade of scaphocerite with anterior margin more advanced at inner than at outer angle. Usually with large circular spot on abdominal somite 6...................................... Crangon nigromaculata

– Abdominal somite 5 carinate. Blade of scaphocerite with anterior margin more advanced at antero-internal angle. No large circular spot on abdominal somite 6...................................................................... 19

19. Scaphocerite broad, short, 0.5 times as long as carapace length or less, abdominal somite 5 with weak dorsal carina................................................................................................ Crangon handi

– Scaphocerite longer, more narrow, 0.66 times as long as carapace length or more, abdominal somite 5 with noticeable dorsal carina............................................................................................. 20

20. Apex of scaphocerite narrow, lateral tooth long, exceeding blade, finger of hand at about 45˚ angle to hand.................................................................................................... Crangon alaskensis

– Apex of scaphocerite broad, lateral tooth generally shorter, barely exceeding blade, finger of hand at about 30˚ angle to hand.................................................................................... Crangon nigricauda

21. Hand of pereopod 1stout, 2.25 times as long as wide, anterior margin more longitudinal than transverse. Antepenultimate segment of third maxillipeds greatly dilated......................................................... Crangon alba

– Hand of pereopod 1 elongate, 3 times as long as wide, anterior margin more longitudinal than transverse. Antepenultimate segment of third maxillipeds not dilated......................................................... Crangon holmesi