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158 Family Palaemonidae
Genus Periclimenes Costa, 1844
Key to species
[Adapted from Chace, 1972]
1. Antennular peduncle with only 1 spine at distolateral angle of basal segment (in
addition to stylocerite) 2
Antennular peduncle with 2 or more spines at distolateral angle of basal segment (in
addition to stylocerite) 9
2. (1) Carapace with anterior margin unarmed (antennal spine absent; third pereopod with
distinctly biunguiculate dactylus) P. longicaudatus
Carapace armed with antennal spine below suborbital lobe 3
3. (2) Fifth abdominal pleuron with posteroventral angle pointed; telson with anterior pair
of dorsal spines arising about one-third of length from base of segment;
scaphocerite with distal spine overreaching distal margin of blade . P. americanus
Fifth abdominal pleuron with posteroventral angle rounded; telson with anterior pair
of dorsal spines arising at, or posterior to, midlength of segment; scaphocerite with
distal spine rarely reaching as far as distal margin of blade, usually falling far short.
4
4. (3) Third abdominal somite strongly produced posteromesially into laterally
compressed hump 5
Third abdominal somite sometimes moderately produced posteromesially but never
forming laterally compressed hump 6
5. (4) Third pereopod with dactylus simple and considerably more than one-third as long
aspropodus P. magnus
Third pereopod with dactylus distinctly biunguiculate and not more than one-fourth
as long as propodus (carapace with hepatic spine usually arising at, or posterior to,
level of posterior tooth of rostral series; carpus of major second pereopod usually
more than half as long as chela) P. pedersoni
6. (4) Rostrum elongate, more than four times as long as maximum height, one or more of
ventral teeth prominent (first pereopod with carpus not noticeably longer than chela;
sixth abdominal somite less than twice as long as fifth and shorter than telson;
scaphocerite with blade far overreaching distal spine; second pereopod with fingers
slightly more than half as long as palm, carpus about one-fifth as long as chela)
P. pandionis
Rostrum subtriangular in lateral view, less than four times as long as maximum
height, ventral teeth inconspicuous or absent 7