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Hyliola hypochondriaca (Hallowell, 1854)

Treefrog, Pseudacris regilla, and Hyla regilla.  Adult males reach at least 33 mm SUL; adult females reach 44 mm SUL.New metamorphs are 11 to 16 mm SUL.  Coloration is variable.  Adults can be bright green or dark brown with a stripe that extends from the nostril to the insertion of the front leg.  Dorsal skin is relatively smooth; the ventral skin is granulated.  Males have two advertisement calls: a two-part call, rib-it, or krek-ek, with the last syllable having a rising inflection, and a one-part call known as the enhanced mate attraction call.  They also produce a slow trill encounter call, a release call, and a land call, which is a prolonged one-note sound heard much of the year, but especially during the beginning of the fall rains.There is considerable confusion over the distribution of this species.  This is due in part to a small number of specimens from few known localities as well as confusion over its taxonomy (see below).  In California, it seems to occur from south of Santa Barbara County and Bakersfield; there are populations on the southern California islands, and it is absent from the southeastern California deserts—except for some isolated populations.  It ranges eastward into Nevada and southward into Baja California.  Introduced urban populations are also known in California City and Soda Springs, California.  In Arizona, Rorabaugh et al. (2004) found this frog in cattail and bulrush marshes along the main channel and in backwaters of the Colorado River. The species has also been introduced at Middle Spring and a nearby stock tank in the Virgin Mountains, Mohave County, and at two central Arizona plant nurseries. The species persisted for at least 19 years and successfully reproduced at one nursery, where it was reportedly introduced on ornamental plants imported from San Diego. It is unclear if the lower Colorado River populations are native or introduced.Habitats include forest, woodland, chaparral, grassland, pastures, desert streams and oases, and urban areas.This frog has been considered a form of the Pacific Treefrog, H. regilla.  However, Recuero et al. (2006) used molecular data to separate H. regilla into three species: H. regilla, H. pacifica, and H. hypochondriaca.  The study demonstrated each lineage had long independent evolutionary histories.  Western chorus frogs from the genus Hyliola and eastern chorus frogs from the genus Pseudacris are all terrestrial.  The two genera last shared a common ancestor 25.7 MYA in Asia.  Barrow et al. (2014) suggest that nuclear DNA analysis does not support the separation of this species from Hyliola regilla, suggesting that the two genera may be reunited in the future.The subspecies present in Arizona is the Northern Baja California Treefrog, P. h. hypochondriaca.[/vc_column_text][/vc_column][vc_column width=”1/2″][/vc_column][/vc_row]