THE AMPHIBIA OF OKLAHOMA 



the eggs of one toad (Bufo insidior) are still unknown. The only reasonably 

 complete key to the eggs of the Salientia of the United States has only recently 

 appeared (Livezey and Wright, 1947). The tadpole of Bujo insidior included 

 in the present key has never been found in Oklahoma, the differentiating fac- 

 tors being based on the statements of Smith (1934) for Bujo debilis of 

 Kansas.^ 



The identification of salientian eggs and of adults in Oklahoma presents 

 no unusual difficulties except in a few instances; but the identification of tad- 

 poles is especially difficult, particularly in some groups. Most descriptions and 

 keys are based upon larvae in early metamorphic stages or at the stage when 

 they are about to enter transformation, and younger tadpoles often cannot 

 be identified without raising them to these stages before keying them out. 

 Furthermore, some larvae do not follow the pattern typical of their group, 

 as is seen in the Hylidae, where for example, the tadpole of Acris crepitans 

 Baird superficially resembles the ranid type more than the hylid (i.e., frog 

 more than tree toad). Variations in color in different regions and waters is 

 the rule rather than the exception; and some characteristics of behavior tend 

 to cut across taxonomic lines. Similar larval adaptations, color patterns, mor- 

 phological structures, and behavior in securing food and protection of dif- 

 ferent species in a single pool at times may be confusing. Within Bufo, tad- 

 poles of some species resemble each other closely at certain stages but differ 

 at others, and many toad tadpoles resemble those of frogs in color, general 

 appearance, and behavior in the face of danger. 



Nevertheless, my whole experience indicates that characteristics of be- 

 havior at given places and conditions often can be used successfully in at least 

 preliminary and tentative identification in the field; and in some cases when 

 combined with known ecological requirements of the species, geographical 

 distribution, and characteristics (and easily recognized markings or morpho- 

 logical structures) will identify tadpoles almost at a glance. If one uses such 

 characteristics with judgment and caution they can be very valuable. But in 

 case of doubt, careful study of morphological structures and proportions is 

 the only safe procedure. 



The key to tadpoles is constructed in the attempt to take advantage of 

 these easily recognized characteristics in the field. Since many of them cannot 

 be used for preserved animals, particularly whenever the water from which 

 they came is unknown, the key presupposes two conditions: (1) The user is 

 observing live tadpoles in nature, or (2) he has live or preserved animals be- 

 fore him in the laboratory with little or no knowledge of their source, except 

 perhaps the general regions of the state where they were collected. The field 

 key begins with No. 1, the general key with No. 18. Any tadpole should be 

 identifiable by beginning with the latter number. Time can be saved under 

 field conditions, however, by starting with the field key. 



In addition to the keys there is a section in which each species is listed 

 alphabetically, with summaries of data on distribution, ecological relations, 



^ Bufo insidior (Jirard was taken out of synonomy witli B. debilis Girard by Taylor 

 (1936). The form in Kansas and Oklahoma is B. insidior. 



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