Section II

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Horton H. Hobbs Jr.
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Key Contents (Species)
 

 

KEY TO THE MALE MEMBERS OF THE NORTH
AMERICAN CRAYFISH GENERA


(Except for Pacifastacus, all based on first form Males)

 


NOTE:  Before beginning to use this key, it will be helpful to determine whether the first pleopods
               are symmetrically or asymmetrically arranged  -- see Figure 21.


 

1.   Ischia of all pereiopods lacking hooks (Fig. 4f:  see also Fig. 5a):  ASTACINAE:................................
      ...................................................................................................................................... Pacifastacus  Bott, 1950 

  • Ischia of 1 or more pairs of pereiopods with hooks (Fig. 4a-c) ..............................................................   2

 


Fig. 4. Ventral view of basal portions of left pereiopods with ischia bering hooks shaded.

2 (1).  Ischia of second and third pairs of pereiopods with hooks (Fig. 4b; see also Fig. 5c):
          CAMBARELLINAE:  ...................................................................................Cambarellus Ortmann, 1905a.

  •     Ischia of second pair of pereiopods never bearing hooks (Fig. 4a, c-e): CAMBARINAE:................
        .......................................................................................................................................................................    3

3 (2).  Body pigmented; eyes faceted and pigmented........................................................................................     4

  •     Body albinistic; eyes seldom faceted and with pigment greatly reduced or absent ........................    12

4 (3).  First pleopod terminating in 2 elements; long, slender central projection; short mesial process no
           more that length of central projection (Fig. 5w);  central projections of paired pleopods
           overlapping (Fig. 19): ...........................................................................  Faxonella Creaser, 1933 (p.29)

  •     First pleopod terminating in 2 or more elements; if with 2, mesial process more than length of
        central projection; central projections of paired pleopods never overlapping (Fig. 5d-v) except
        occasionally in Fallicambarus dissitus in which also recurved at more than 90 degree
        angle (Figs. 81c, 82d): ...........................................................................................................................     5

5(4).   First pleopod terminating in 2 elements (Fig. 5h-i, 1-p) ........................................................................      6

  • First pleopod terminating in more than 2 elements (Fig. 5d-g, k, q,v)..................................................     10

6(5).   Distal 1/3 of first pleopod with prominent shoulder on cephalic surface (Fig. 5h), or central projection
           forming distally projecting triangular plate (Fig. 5j), or central projection arising from enlarged
           subterminal or terminal area (Fig. 5i):...................................................  Procambarus Ortmann, 1905b (part). 

  •  Distal 1/3 of first pleopod lacking shoulder on cephalic surface; central projection never forming
     distally projecting triangular plate nor arising from enlarged subterminal or terminal area
     (Fig. 51-p, r-u):  ............................................................................................................................................     7

 
Fig. 6.  Ventral view of basal podomeres of left third, forth, and fifth pereiopods showing variations in coxae (stippled) of fourth (a. without boss;  b-d, with boss).  a) Procambarus digueti;  b) P. paeninsulanus;  c) P. riojai;  d) P. tenuisb = boss.

7(6).   Coxa of fourth pereiopod lacking caudomesial boss (Fig. 6a)...................................................................    8

  •     Coxa of fourth pereiopod with caudomesial boss (Fig. 6b-d) ...............................................................     9

8(7).   First pleopods, in resting position, deeply withdrawn between bases of pereiopods and largely
           concealed by dense setiferous mat extending from ventrolateral  margins of sternum (Fig. 7a):
           ...............................................................................................................Hobbseus Fitzpatrick and Payne, 1968.

  •     First pleopods, in resting position, never deeply withdrawn between bases of pereiopods and
        never concealed by dense setiferous mat extending from ventrolateral margins of sternum
        (Fig. 7b):  ......................................................................................................Orconectes Cope, 1872 (part).

9(7).   Opposable margin of dactyl of chela with abrupt excision in proximal (Fig. 8a):............................
            .....................................................................................................................Fallicambarus Hobbs, 1969b (part).

  •     Opposable margin of dactyl of chela without abrupt excision in proximal (Fig. 8b-e):...............
        .......................................................................................................................Cambarus Erichson, 1846 (part).

 

Fig. 7.  Ventral thoracic region of a) Hobbseus; b) Orconectes.


10(5).   Central projection of first pleopod bladelike, always directed caudally or caudodistally, and
              bearing subterminal notch (n) (Fig. 5q): ..............................................................................Cambarus (part).

  •      Central projection of first pleopod seldom bladelike, if so, directed laterodistally or lacking
          subterminal notch (Fig. 5d-g, v): ................................................................................................................     11

Fig. 8.  Dorsal view of right chela.  a) Fallicambarus oryktes;
b)  Cambarus latimanus;  c) C. longulus;  d)  C. extraneus;  e)  C. branchydactylus.

11(10).  First pleopod with central projection and mesial process curved caudally at at least 90 degrees to
              principal axis of shaft of appendage (Fig. 5v): .................................................................Fallicambarus (part).

  •       First pleopod never with both central projection and mesial process curved caudally at angle of
         so much as 90 degrees to principal axis of shaft of appendage (Fig. 5d-g): .............Procambarus (part).

Fig. 9.  Ventral view of left third maxillipeds.  a) Troglocambarus maclanei; b)  Procambarus pallidus.  (i, ischium).

12(3)    Ischium of third maxilliped (See Fig. 2) without teeth on mesial  (opposable) border (Fig. 9a;
             see also Fig. 5b):.............................................................................................Troglocambarus Hobbs, 1942a.

            Monotypic: Troglocambarus maclanei Hobbs. 1942.  (Subterranean  waters of peninsular Florida.
             Literature:  Hobbs, 1942b)

  •       Ischium of third maxilliped with teeth on mesial (opposable) border (Fig. 9b):.....................................  13

Fig. 10.  Lateral view of left first pleopods.  a) Cambarus hamulatus;  b) C. jonesi;  c) C. setosus;  d) C. hubrichti;  e) C. cryptodytes.

13(12). First pleopod terminating in 2 elements bent at no less that 90 degrees to principal axis of shaft
              of appendage (Fig. 10):  ..........................................................................................................Cambarus (part).

  •       First pleopod terminating in 2 or more elements; if only 2, both never bent at angle so great as 90
         degrees to principal axis of shaft of appendage (Fig. 11): .....................................................................   14

Fig. 11.  Lateral view of first pleopods.  a) Orconectes a. australis;  b) P. pellucidus;  c) O. i. inermis;  d) Procambarus acherontis;  e) P. l. lucifugus;  f) P. milleri;  g) P. pecki.

14(13). First pleopod terminating in 2 elements, sometimes with minute rudiment of third (Fig. 11a);
             cephalic surface of appendage either lacking shoulder or  with shoulder adjacent to base of
             central projection (Fig. 11b,c):    ............................................................................................Orconectes (part).

  •       First pleopod terminating in 2 (Fig. 11g) or more elements (Fig. 11d-f);  if  only 2, cephalic
         surface with strong, often angular, shoulder never contiguous  with base of central projection
         (Fig. 11g): .........................................................................................................................Procambarus (part).

 


** END OF SECTION II **

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Last Updated:10 September 2004