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(Based on First Form Male By Henry W. Robison, Ph.D. as modified from Hobbs, 1992 Key to Arkansas Crayfishes, 9/2000 update)
Note to Users: Descriptive words that are highlighted as active links will take you to the Glossary for a definition. These glossary terms are only highlighted on their first occurrence in the key. Use the back button on your browser to return to this key. Numbers that are highlighted as active links will take you to that place in this key. Species names that are highlighted as active links will take you to the species account for that species. Use the back button on your browser to return to this key.
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1
a. First pleopods with more than two terminal elements. 2
b. First pleopods with no more than two terminal elements. 9
2
a. First pleopods with two or three terminal elements bent at least right angle to shaft of appendage. 3
b. First pleopods with three or more terminal elements, none with two bent caudally at as much as right angle to shaft of appendage. 4
3
a. Cephalic process of first pleopod directed caudodistad. Fallicambarus harpi
b. Cephalic process of first pleopod directed caudally, parallel to mesial process. Fallicambarus strawni
4
a. Hooks on ischia (ischiopodite) of third pereiopods only; boss lacking on coxa of fourth pereiopod. 5
b. Hooks on ischia of third and fourth pereiopods; boss present on coxa of fourth pereiopod. 8
5
a. Opposable margin of dactyl of chela with prominent angular excision in basal third; dorsolateral surface of palm punctate. 6
b. Opposable margin of dactyl of chela lacking or with weak excision in basal third; dorsolateral surface of palm tuberculate. 7
6
a. Areola less than 30 times as long as broad. Procambarus reimeri
b. Areola more than 30 times as long as broad. Procambarus liberorum
7
a. Blade of central projection of first pleopod directed distolaterally, and, in caudal aspect, extending lateral to central projection. Procambarus curdi
b. Blade of central projection of first pleopod directed distally, and, in caudal aspect, situated mesial to central projection. Procambarus parasimulans
8
a. Carapace with 2 or more cervical spines on each side. Procambarus ouachitae
b. Carapace with or without 1 cervical spine on each side. Procambarus acutus
9
a. Hooks on ischia of third and fourth pereiopods. Procambarus tenuis
b. Hooks on ischia of third pereiopods only. 10
10
a. First pleopod with one ramus (central projection) at least twice as long as other (mesial process). Faxonella blairi
b. First pleopod never with one ramus as much as twice length of other. 11
11
a. First pleopod with terminal elements bent caudally at base at least 90 degrees to shaft of appendage 12
b. First pleopod with terminal elements directed distally, or if strongly bent, curvature beginning distal to base. 13
12
a. First pleopod with proximomesial spur. Fallicambarus jeanae
b. First pleopod lacking proximomesial spur. Fallicambarus fodiens
13
a. Areola obliterated at least at midlength. Orconectes palmeri
b. Areola broad or narrow but never obliterated even in part. 14
14
a. Both terminal elements of first pleopod at least weakly arched caudally. Orconectes sp. nov.
b. Both terminal elements of first pleopod never arched caudally although tip of central projection may be so inclined. 15
15
a. Central projection of first pleopod constituting about 1/2 total length of pleopod. 16
b. Central projection constituting distinctly less than 1/2 total length of pleopod. 17
16
a. First pleopod with angular shoulder on cephalic surface. Orconectes leptogonopodus
b. First pleopod lacking angular shoulder on cephalic surface. Orconectes acares
17
a. First pleopod with central projection reaching basis of first pair of pereiopods when abdomen flexed; distinct shoulder present on cephalic surface. Orconectes saxatilis
b. First pleopod with central projection not reaching forward to the bases of the first pair of pereiopods; distinct shoulder absent on cephalic surface. Orconectes menae
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