Anaxyrus sp. 1

Taxonomy 
Scientific Name:Anaxyrus sp. 1
Common name:Dixie Valley toad
Rank and Status   
Global Rank:GU Native Status:Native
Subnational (State) Rank:S1 Endemic:Yes
US ESA Status:None Sand Dunes:No
NNHP Tracking Status:At-Risk List Wetland:Yes
Other Agency Status Status Last Updated Status Comments
Bureau of Land Management - Nevada Sensitive BLM Nevada Sensitive Species List dated 2017-10-01
Distribution (NV Counties)

Status: Confident or certain

Churchill
Summary Occurrence Data
Occurrence Count:1
Total Observed Area (hectares):Not Available
Maximum Known Elevation (m):Not available
Minimum Known Elevation (m):Not Available
Links
Anaxyrus sp. 1 data at NatureServe
Anaxyrus sp. 1 photos and data at Encyclopedia of Life
Character Abstract
Identification Comments:Some morphology of the Dixie Valley toad is quite distinct from that of western toads. Dixie Valley Toads are markedly smaller than western toads and far more colorful. The Dixie Valley toad’s relatively large, closely set eyes large tympanum, and its unique coloration distinguish this species from all other taxa within the B. boreas species complex (Gordon et al. 2017).
Subspecies Comments:Phylogenetic analysis of mtDNA data from throughout the range of the <i>Bufo </i>(<i>Anaxyrus</i>) <i>boreas </i>species group (including <i>boreas</i>, <i>canorus</i>, <i>exsul</i>, and <i>nelsoni</i>) by Goebel et al. (2009) identified three major haplotype clades. The Northwest clade (NW) includes both subspecies of <i>boreas </i>(<i>boreas </i>and <i>halophilus</i>) and divergent minor clades in the middle Rocky Mountains, coastal, and central regions of the west, and Pacific Northwest.<br />However, Forrest et al. (2017) found very little mtDNA sequence difference for the Dixie Valley Toad (DVT) or McCoy Ranch toads (a population 50 km north of Dixie Valley) analyzed with respect to the range of <i>A. boreas</i> sequences presented by Goebel et al (2009). In fact, 6 of the DVT samples (DM1, DM3, DM4, DM6, DS1, and DS2) that were analyzed are identical to <i>A. boreas</i> sequences from Beaverhead County, Montana The maximum likelihood phylogenetic analysis of the combined CR and COI data provides no evidence to support the hypothesis that the DVT is a distinct species or subspecies. Instead, the DVT forms part of the well-supported North Western <i>A. boreas</i> clade identified in Goebel et al. <br />Confounding matters further, additional research (Gordon et al. 2017) using 14 distinct morphological characteristics as well as genomic DNA extracted from tissue has been offered to provisionally describe the Dixie Valley toad as a distinct species:  <i>Anaxyrus williamsi.</i><br />Regardless of each of the above mentioned researchers’ conclusions, the DVT should be recognized as a distinct management unit and protected as such.
Food Habits:
Phenology Comments:During surveys in March-May, Dixie Valley Toads (DVT) were actively mating and egg masses and tadpole aggregations were also often observed. Amplexus in DVT often occurs underwater (usually &lt;1m) along the banks of the perennial wetland habitat in Dixie Meadows. Developmental stages were investigated and recorded using the Gosner method (Gosner, 1960). Calling males were first detected in early March ovodeposition was first observed in April and the first wave of completely metamorphosed toadlets was observed 10 weeks later in June.  Newly metamorphosed toads (n=12) had mean SVL = 15.25 mm (Fig. 9) and a mean weight of 0.375 grams. 13 weeks later in September weighed and measured metamorphed toads (n=14), mean SVL = 18.21 mm and mean weight 0.625 grams.
Reproduction Comments:During surveys in March-May, Dixie Valley Toads (DVT) were actively mating and egg masses and tadpole aggregations were also often observed. Amplexus in DVT often occurs underwater (usually &lt;1m) along the banks of the perennial wetland habitat in Dixie Meadows. Developmental stages were investigated and recorded using the Gosner method (Gosner, 1960). Calling males were first detected in early March ovodeposition was first observed in April and the first wave of completely metamorphosed toadlets was observed 10 weeks later in June.  Newly metamorphosed toads (n=12) had mean SVL = 15.25 mm (Fig. 9) and a mean weight of 0.375 grams. 13 weeks later in September weighed and measured metamorphed toads (n=14), mean SVL = 18.21 mm and mean weight 0.625 grams.
Migration Mobility:
Habitat Comments:The Dixie Valley toad is found in spring-fed wetlands and surrounding upland habitat on the western edge of the Dixie Valley Playa (Ibid. at 134). The habitat separating the four spring discharge sites and their downstream marsh habitat consists of sagebrush steppe dominated by big sagebrush (Artemisia tridentata ssp. tridentata), greasewood (Sarcobatus vermiculatus), rubber rabbitbrush (Ericameria nauseosa) and saltbush (Atriplex spp.) The spring-fed wetlands relied upon by the toad typically contain spikerush (Eleocharis spp.), three-square bulrush (Schoenoplectus sp.), knotweed (Polygonum spp.), canarygrass (Phalaris spp.), duckweed (Lemna sp.), various species of rush (Juncus sp.), common reed (Phragmites australis), and cattail (Typha spp.) .
Ecology comments:Dixie Valley is a cold-desert ecosystem, experiencing extreme temperature fluctuations between daytime and nighttime temperatures, with daily fluctuations often exceeding 20 ºC, as well as seasonal extremes, ranging from &lt;0 ºC in winter to &gt;0 ºC in summer (Forrest et al. 2017). The Dixie Valley toad relies on only four wetlands fed by geothermal springs, which are the only perennial sources of habitable freshwater in the toad’s native habitat. The soils in the surrounding areas contain very dry, alkaline playa deposits covered with salt crusts, which likely serves as an impassible barrier for the toads (Forrest et al. 2017).
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