INTRODUCTION 



The Teiid lizard genus Cnemidophorus attains its highest diversity 

 in North America within the borders of the state of New Mexico. Li- 

 zards of this genus are dominant components of the terrestrial fauna, 

 yet their biology is only now being understood. Indeed, with one not- 

 able exception, little was known about the North American species twen- 

 ty years ago except that they were highly confusing taxonomically. 

 Then, this genus was discovered to be unique among vertebrates with 

 its high proportion of unisexual taxa. Fully one-half of the forms 

 in New Mexico are obligate parthenospecies; each of these is derived 

 from hybridization events between two or more sexual species of the 

 genus. They are clonally diverse in some cases, perhaps all; that is, 

 they manifest genetic and morphological variability somewhat approach- 

 ing that of sexual species although localized populations are usually 

 quite homogeneous. The ecological and evolutionary interactions of 

 these parthenospecies with each other, and with their sexual congeners, 

 is only now being detailed. 



One cannot study this genus without coming to grips with the laby- 

 rinthine snarl of its taxonomy. Systematic solutions have spanned the 

 gamut from minute detailing of non-significant variation to simply ig- 

 noring differences. The genus is a diverse one, and much of the confu- 

 sion resulted from an unawareness of hybrid parthenogenetic clones 

 within it. Morphological characters can be more or less variable in 

 clones than in sexual populations, depending upon the character and the 

 scope of the examination. The parthenospecies considered here do pre- 

 sent a taxonomic problem. The biological species concept, which re- 

 quires free intraspecific exchange of genetic material, obviously does 

 not apply to them. They just as obviously exist. How does one deal 

 with them on a taxonomic basis? Again, solutions ranged from giving 

 each separate clone specific rank to taxonomically ignoring them. I 

 agree with Maslin, Wiley and others that each successful parthenogen- 

 etic clone does have an evolutionary life span and with the modifica- 

 tion of Simpson's evolutionary species concept to include them. I pro- 

 pose a further step. One has to know what organisms one is dealing 

 with in order to do biology well. This is part of the fundamental 

 utility of the biological species concept, yet it has not been applied 

 to parthenogenetic Cnemidophorus without ambiguity, confusion, and con- 

 troversy. The capability exists, detailed in this bibliography, to 

 identify the parental sexual species of each parthenospecies of Cnemi- 

 dophorus . I propose that a given species name be applied and restric- 

 ted to a particular combinatorial sequence, past, present or future, of 

 successful hybridization events. Thus, the name Cnemidophorus neomexi- 

 canus will be uniquely applied to clones originating from _C. inornatus 

 X _C. tigris events. This will obviate the necessity of applying multi- 

 ple names to a clonal species complex (Zweifel's pattern class system 

 will serve admirably in this regard) and of naming (or ignoring) aber- 

 rant individuals representing chance hybrid events that do not repre- 

 sent successful populations. Most important, I believe this scheme 



