Tennessee River and Crawfish Distribution 125 



stocks organized around an adorconectoid stock. (Mexican diversity, 

 especially interesting to a zoogeographer, is outside the realm of this 

 treatment.) From the former (earlier) populations we see today members 

 of the subgenera Capillicambarus , Hagenides, Lonnbergius, Ortmanni- 

 cus, Pennides, Scapulicambarus , Tenuicambarus, and Villalobosus, plus 

 the genus Troglocambarus . 



From the adorconectoid line (later temporally), stocks developed 

 that culminate in the procambarid subgenera Acucauda, Austrocambar- 

 us, Girardiella, Leconticambarus , Mexicambarus, Paracambarus, Pro- 

 cambarus, and Remoticambarus , plus the genera Barbicambarus , Cam- 

 barus, Distocambarus, Fallicambarus, Faxonella, Mobbseus, and 

 Orconectes. One of the more striking features of the latter assembly is 

 that, except for Cambarus and Distocambarus, geographically they are 

 more or less western (in relation to the proposed center of origin of the 

 cambarines). Although not a complete "family tree" for the Cambari- 

 dae, Figure 11 of Hobbs's Georgia monograph (1981) is adequate to 

 demonstrate his ideas. He does not visualize polyphyletic origins; instead, 

 he sees the non-procambarid genera as widely divergent stocks that orig- 

 inated from divers stocks of Procambarus. (The groupings as I have 

 made them fundamentally rest on Hobbs, as I have cited him; but if 

 they prove to be non-congruent to his concepts, the fault is entirely 

 misinterpretation on my part.) This latter adorconectoid line seemed to 

 be the less conservative of the two main Procambarus stocks, as evi- 

 denced by the extremes — recognized as genera — of apomorphies devel- 

 oping in it. 



Another early divergence from the cambarine-procambarid stock 

 resulted in the monogeneric Cambarellinae. Hobbs' last lengthy discus- 

 sion of this phylogeny (1969) was concerned with establishing the rela- 

 tionships between the Cambarinae and the Cambaroidinae, taking for 

 granted an understanding of the close association of the former and the 

 Cambarellinae. More recently, Fitzpatrick (1983) addressed the infrage- 

 neric relationships of the members of Cambarellus and tried to establish 

 their phylogenetic affinities with other Cambaridae. The dwarf craw- 

 fishes are also basically western in distribution. 



The determination of these lineages did not, however, afford non- 

 moot concepts and explanations of current distributions. Indeed there 

 are many enigmas and paradoxes. Among these are the geographic 

 ranges of those Cambarellus most like the ancestral form, and an expla- 

 nation of why the culminations of an early offshoot of cambarine evolu- 

 tion would be excluded from the proposed ancestral home. Yet they 

 seem to be highly competitive and successful against advanced (and 

 therefore, competitively selected) members of groups that emerged at a 

 later date (Penn and Fitzpatrick 1962, 1963). 



Members of the subgenus Pennides have many characters attribu- 

 table to the "ancestral procambarid": a full complement of simple ter- 

 minal elements on the male pleopod; multiple carapace spines; a short, 



