Three new bufonid (Bufo (Anaxyrus)) species discovered within the Great Basin and the consequences of taxonomic crypsis

Abstract

The Great Basin is one of the most arid ecoregions in the United States, yet this desert is far from devoid of life. The state of Nevada, which comprises much of the Great Basin interior, ranks high among states within the United States in biodiversity and endemism. Studies evaluating the biogeography within the region have suggested that the Great Basin’s complex climate history and geological processes both combined to be important drivers of ecological and species diversity. Anurans are among the rarest group to occur within the desert ecoregion, yet Bufo (Anaxyrus) boreas (Western toad) occurs across the Great Basin. This toad has a broad geographic range throughout the Western United states, but three narrow endemic bufonids closely related to the western toad are confined to the Great Basin: B. (Anaxyrus) canorus (Yosemite toad), B. (Anaxyrus) exsul (black toad) and B. (Anaxyrus) nelsoni (Amargosa toad) and as a whole, comprise the B. boreas species complex. Our recent molecular genetics study has uncovered cryptic lineages within several spring localities within the Great Basin. Here, we combine molecular methods and comparative morphological analyses to quantify both genetic and morphological character differences among the congeneric taxa of the B. boreas species complex, resulting in delimiting three new endemic bufonids, demonstrating that our knowledge of the region’s biodiversity remains incomplete and new discoveries are still possible. However, these newly described toads (a) occupy severely restricted ranges, (b) are vulnerable to disease and invasive species, (c) and human exploitation, all of which contributes to the increased risks of extinction for these cryptic species which are not accurately reflected by current taxonomy. The consequences of taxonomic crypsis include improper conservation for these localized species and undermines our understanding of biodiversity.