Distinguishing the Treefrogs "Hyla versicolor" and "Hyla chrysoscelis" in Iowa, and Their Distributions

Abstract

Historically, the tetraploid and diploid species pair of treefrogs, "Hyla versicolor" and "Hyla chrysoscelis" have been mapped collectively in Iowa because no distinguishing macroscopic morphological characteristics useful in recognizing the two species had been found. The present study reports identification and separation of the species by counts of stained nucleoli and measurement of scanning electron micrographs of toepad projections. The resulting distribution correlates with spot checks of call analysis. Subsequent morphometric data confirm that the two species represent two distinct populations in Iowa. "H. chrysoscelis" is distributed sporadically through the southwestern half of Iowa while "H. versicolor" is limited to the southeastern half of the state. This study suggests a decline of these species in extreme northern Iowa.