Lithobates chiricahuensis

Based on mitochondrial and nuclear DNA data, some from century-old museum specimens, Hekkala et al. (2011) determined that populations of L. chiricahuensis from the Mogollon Rim in central and east-central Arizona and adjacent western New Mexico actually represent L. fisheri, previously regarded to be extinct and restricted to southern Nevada. Previously, Sredel et al. (1997) recognized these populations as a distinct species (Rana sp. 1).

USFWS (2012) notes that although data likely support ascribing all known populations of L. chiricahuensis to L. fisheri, the phylogenetic tree in Hekkala et al. (2011) is a subset of a larger phylogenetic tree that is still under construction and recommended making no changes until the more comprehensive phylogeny is available.

"Rana subaquavocalis," here included in Rana (Lithobates) chiricahuensis, formerly was regarded as a distinct species. Goldberg et al. (2004) used mtDNA sequences to investigate the phylogenetic relationship of ubaquavocalis and chiricahuensis, based on 39 samples of subaquavocalis and 53 samples of chiricahuensis from localities throughout their Arizona range. They found two distinct lineages of chiricahuensis, one on the Mogollon Rim of central Arizona and one in southern Arizona. "Rana subaquavocalis" samples were on a short branch within the southern Arizona clade of chiricahuensis. The results are consistent with the hypothesis that chiricahuensis and subaquavocalis are conspecific. Based on this evidence, Crother (2008) and Frost (2009) regarded subaquavolcalis as a synonym of chiricahuensis.

Goldberg et al. (2004) concluded that the two chiricahuensis lineages could represent two distinct species, but they suggested that a detailed examination of behavioral, ecological, and morphological differences between the groups be conducted before this is determined.

Populations from southern Chihuahua and Durango to Aguascalientes, reported to be R. chiricahuensis, may represent another species (see USFWS 2000, 2002).

This species hybridizes with R. yavapaiensis, the lowland leopard frog, and R. pipiens, the northern leopard frog, in areas where their ranges overlap (Green and Delisle 1985, Stebbins 1985).

Range extends from Arizona and New Mexico into Mexico; formerly declining in the U.S., due primarily to effects of habitat loss and degradation, introduced species, and disease; now stabilized and improving, though still facing threats from disease, non-native species, and drought; trend and status in Mexico are poorly known.

This species occurs from southeastern Arizona (drainages of the Madrean Archipelago and surrounding desert grasslands, south of the Gila River in Cochise, Santa Cruz, Pima, and Graham counties) and extreme southwestern New Mexico (Hidalgo County) in the United States, south along the eastern slope of the Sierra Madre Occidental in Sonora and Chihuahua, Mexico, where the southern range limit is poorly defined due to taxonomic uncertainties. Also included in L. chiricahuensis are additional populations in the upper Gila River drainage in extreme eastern Arizona and southwestern New Mexico. The populations in central Arizona and westward along the Mogollon Rim to portion of southwestern New Mexico are considered to be L. fisheri by Hekkala et al. (2011), but this determination is considered premature by others (USFWS 2012). Elevational range extends from about 1,000 to 2,710 meters.

The frog formerly known as Rana subaquavocalis is known from areas within a 10-km radius in the Huachuca Mountains; current known range is limited to aquatic habitats in Tinker, Brown, Ramsey, and Miller canyons and several residential ponds in the area, Cochise County, Arizona (Platz 1993, Platz and Grudzien 1993, Platz et al. 1997, Arizona Game and Fish Department 2001, Platz and Grudzien 2003). It currently exists in several canyons on the east side of the Huachuca Mountains (Goldberg et al. 2004) and ranges in elevation from 4,925 to 6,001 ft. (1502 - 1830 m) (Sredl et al. 1997).

USFWS (2012) reported that there are 33 known breeding populations in Arizona and 20-23 in New Mexico (some of these are now identified as L. fisheri; Hekkala et al. 2011). These represent about 131-133 sites with extant populations (USFWS 2011). This species is represented by somewhat fewer than a few dozen occupied critical habitat units (USFWS 2012), each of which could be regarded as constituting a population or metapopulation.

Including northern montane populations, the species is known historically from 231 locations in Arizona, 182 sites in New Mexico, and about a dozen sites in Mexico (USFWS 2002), though some of these now are allocated to Lithobates fisheri (Hekkala et al. 2011).

The frog formerly known as Rana subaquavocalis is extant at four sites, with regular successful breeding occurring at two sites (Platz et al. 1997). Known number of breeding sites has been reduced to one (E. Wallace, pers. comm., cited by Platz and Grudzien 2003). Through intensive conservation actions, including translocations, this frog is currently found in five canyons on the east side of the Huachuca Mountains (Goldberg et al. 2004).

USFWS (2012) determined that the most significant threats to the Chiricahua leopard frog include the effects of the disease chytridiomycosis, which has been associated with major die-offs in some populations of Chiricahua leopard frogs, predation by nonnative species (e.g., centrarchids, bullfrogs, tiger salamanders, crayfish; USFWS 2000, 2002), and drought (though some sites are buffered from the effects of drought by wells or other anthropogenic water supplies; USFWS 2011). Additional factors affecting the species include degradation and loss of habitat as a result of water diversions and largescale groundwater pumping, livestock management practices (such that grazing is not in accordance with approved allotment management plans or otherwise considered adverse to maintaining natural habitat characteristics), altered fire regimes due to fire suppression, mining, contaminants, agricultural development, and other human activities; and inadequate regulatory mechanisms regarding introduction of nonnative bait species (USFWS 2012). It is unclear how ongoing climate change will affect this species (USFWS 2011).

Although progress has been made to secure some existing populations and establish new populations , the status of the species continues to be affected by threats such that the species is likely to become endangered within the foreseeable future throughout all or a significant portion of its range (USFWS 2012). Due primarily to ongoing conservation measures and the existence of relatively robust populations and metapopulations, USFWS (2012) determined that the species is not in immediate danger of extinction (i.e., on the brink of extinction). However, present threats (such as chytrid fungus and nonnative predators spreading and increasing in prevalence and range, and affecting more populations of the leopard frog) are likely to continue in the future (USFWS 2012),

The following refers to the frog formerly known as Rana subaquavocalis: Elimination of beavers, which create favorable habitat, and diversion of water for irrigation, likely contributed to the decline of populations that may have existed in the San Pedro River (about 8 km east of Ramsey Canyon) (Platz and Grudzien 2003).

Threats include natural flooding (which could destroy or degrade breeding sites), and exotic competitors (e.g., bullfrog), predators, or pathogens. The few, small populations in a dynamic environment make the species particularly vulnerable to extinction. The Ramsey Canyon and Brown Canyon populations probably are isolated and may not function as part of a single metapopulation.

In early summer of 1996, a severe drought caused the Barchas Ranch duck pond to dry out, eliminating it as suitable breeding habitat (Platz and Grudzien 2003). In 2000, a dead frog in Ramsey Canyon was documented to have a chytrid fungal infection (M. Sredl, pers. comm., cited by Platz and Grudzien 2003). At two sites, Tinker Pond and Ramsey Canyon, chytrid fungus has been found in dead frogs (Arizona Game and Fish Department 2001). This fungus has been implicated in the declines of amphibians around the world (Berger et al. 1998) and may play a role in the decline of R. subaquavocalis.

Extirpation of two populations was associated with low levels of heterozygosity (Platz and Grudzien 2003).