AmphibiaWeb - Pseudacris kalmi
Pseudacris kalmi
New Jersey Chorus Frog
family: Hylidae
subfamily: Hylinae
Species Description: Lemmon EM, Lemmon AR, Collins JT, Lee-Yaw JA, Cannatella DC 2007 Phylogeny-based delimitation of species boundaries and contact zones in the trilling chorus frogs (Pseudacris). Mol Phylog Evol 44:1068-1082.

© 2012 Will Lattea (1 of 7)
Conservation Status (definitions)
IUCN (Red List) Status Least Concern (LC)
NatureServe Status Use NatureServe Explorer to see status.
National Status None
Regional Status None
Access Conservation Needs Assessment Report.



View distribution map in BerkeleyMapper.

Overall adult snout-vent length for Pseudacris kalmi range is 19 – 36 mm (Dodd 2013, Powell et al. 2016). More specifically, for males, the snout-urostyle length range is 28 – 32 mm and for females, the range is 29 - 36 (Dodd 2013).

Tadpoles have a total body length of 25.4 - 38.1 mm long. Froglets have a snout-urostyle length range 8 - 12 mm (Dodd 2013).

Pseudacris kalmi has a prominent light line that runs over the upper lip and below the eyes. The limbs are longer in comparison to other species in the P. nigrita clade. In appearance, they are most similar to the Upland Chorus Frog (P. feriarum) (Powell et al. 2016) and the Western Chorus Frog (P. maculata) (Dodd 2013). Unlike P. feriarum, P. kalmi have a distinct dim, dark stripe along the tibia and the dorsal stripes are wider and more uneven (Dodd 2013), and P. maculata is distinguishable by its shorter legs (Dodd 2013, Powell et al 2016).

The background color usually ranges from gray to brown but may be greenish-olive in some individuals (Dodd 2013). The species three distinct dark brown, broad dorsal stripes that are usually unbroken (Dodd 2013, Powell et al. 2016) and are darker than the body color. They also have a well-defined interorbital triangular spot that reaches onto their eyelids (Dodd 2013).

Ventrally, the tadpoles’ coloration ranges from dark brown to olive, and dorsally they have a bronze hue. Their tails are translucent with black speckling, and have darker tones ventrally and lighter tones dorsally, corresponding to the color pattern of the body (Dodd 2013, Gosner and Black 1957).

In adults, there are rare instances where the dorsal stripe is broken at the middle stripe (Powell et al. 2016).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: Maryland, New Jersey, Virginia


View distribution map in BerkeleyMapper.
Pseudacris kalmi are found in the United States and range from southern New Jersey into the Delmarva Peninsula, which includes Maryland, Delaware, and Virginia (Powell et al. 2016). Their habitat includes grassy floodplains and wet woodlands that have shallow wetlands such as ephemeral pools, ditches, wooded swamps, and freshwater marshes (Felbaum et al. 1995, White and White 2002, Powell et al. 2016). Outside of the breeding season (July to January), they are found in woodland areas where the forest is moist (Dodd 2013).

Life History, Abundance, Activity, and Special Behaviors

Reproductive Behavior: Males and females move to small vernal pools in open habitats to breed from February to June. The males arrive first and call for females from the water surface or while clinging to aquatic vegetation starting in February (Dodd 2013).

Calls: Pseudacris kalmi have short calls that include high pulse rates (Platz and Forester 1988). Their calls can be heard day and night (Dodd 2013). However, there are no formal description of advertisement and territorial calls (e.g. frequency, pulse rate, duration).

Males use axillary amplexus (Gosner and Rossman 1959). Females lay their eggs in loose masses on the stems of shallow aquatic vegetation. The non-breeding season is from July to January (Dodd 2013).

Territorial behavior of P. kalmi is not recorded/unknown.

Development: Egg masses can contain 8 and 143 eggs (Dodd 2013). Eggs are black to brown dorsally with the color at the vegetal pole white. Average diameter of the egg (vitellus and egg capsule) is 3.10 mm (Gosner and Rossman 1959). The timing of egg hatching is likely similar to closely related species (Dodd 2013). The hatching event occurs when the egg reaches approximately 4.7mm, and the tadpoles reach the adult stage after 2 months of development (Gosner and Black 1957).

Diet: Although there has been no formal study of their diet, P. kalmi are presumed to eat a variety of invertebrate prey (Dodd 2013).

Predators: Predators include arthropods like crayfish and water spiders and vertebrates like water snakes, birds, raccoons, and foxes (Mitchell and Anderson 1994).

Trends and Threats
According to Hammerson (2008), no major threats are known, but habitat conversion for human use locally eliminates and reduces populations. There an endangered population in Pennsylvania (Yahner 2003). Hammerson also states that the species needs to be reassessed. The lethal pH level for P. kalmi embryos is 3.8 (Gosner and Black 1957).

The species authority is: Harper, F. A. (1955). “A new chorus frog (Pseudacris) from the eastern United States. Natural History Miscellanea 150:1–6.

Pseudacris kalmi belongs to the northeastern US population of the trilling frog clade (P. nigrita clade). Bayesian analysis of 12S and 16S rRNA genes showed that P. kalmi is sister to the clade formed by P. feriarum and P. triseriata. Together they are sister to the clade formed by P. fouquettei and P. nigrita (Lemmon et al. 2007; Lemmon et al. 2008).

Pseudacris kalmi was originally described as a subspecies of P. nigrita (Harper 1955; Schwartz 1957) and was once recognized as a subspecies of P. feriarum (Crother 2001). More recently, genetic analyses revealed that P. kalmi is distinct from P. feriarum and, instead, belongs to the P. nigrita clade (Lemmon et al. 2007). The contact zone between P. kalmi and P. feriarum is poorly documented (Crother 2017), however there is evidence that P. kalmi breeds with similar species where their ranges overlap (Powell et al. 2016). For example, in southeastern Virginia it hybridizes with P. nigrita (Lemmon et al. 2007).

Synonyms include: Hyla kalmi, Pseudacris feriarum kalmi, Pseudacris nigrita kalmi, Pseudacris triseriata corporalis, and Pseudacris tiseriata kalmi. In select literature, the species is referred to as P. triseriata, and the correct taxonomic allocation is identified by location of the specimens (Dodd 2013).

The epithet "kalmi" is an eponym in honor of Swedish naturalist Peter [Pehr] Kalm, who wrote Travels into North America (1772). He is credited with the first scientific description of Niagara Falls and was an early student of New Jersey frogs (Dodd 2013).


Crother, B. I. (ed.). 2001. “Scientific and standard English names of amphibians and reptiles of North America North of Mexico, with comments regarding confidence in our understanding.” Herpetological Circular No. 29, Society for the Study of Amphibians and Reptiles, Shoreview, MN.

Crother, B. I. 2017. ‘Scientific and standard English names of amphibians and reptiles of North America North of Mexico, with comments regarding confidence in our understanding.’ Herpetological Circular No. 43, Society for the Study of Amphibians and Reptiles, Shoreview, MN [link]

Dodd, C. K. 2013. Frogs of the United States and Canada. John Hopkins University: JHU Press.

Gosner, K. L. (1960). ''A simplified table for staging anuran embryos and larvae with notes on identification.'' Herpetologica, 16(3), 183-190.

Gosner, K. L., Rossman, D.A. (1959). "Observations on the reproductive cycle of the swamp chorus frog, Pseudacris nigrita." Copeia 3: 263-266 [link]

Hammerson, G. (2008). "Pseudacris kalmi". The IUCN Red List of Threatened Species 2008: e.T136134A4247755. Downloaded on 21 March 2021.

Harper, F. A. (1955). "A new chorus frog (Pseudacris) from the eastern United States." Natural History Miscellanea 150:1–6.

Mitchell, J.C., Anderson, J.M. (1994). “Amphibians and Reptiles of Assateague and Chinoteague Islands.” Virginia Museum of Natural History, Special Publication, 2. [link]

Moriarty Lemmon, E., Lemmon, A. R., Collins, J. T., Cannatella, D. C. (2008). "A new North American chorus frog species (Amphibia: Hylidae: Pseudacris) from the south-central United States." Zootaxa, 1675, 1-30. [link]

Moriarty Lemmon, E., Lemmon, A. R., Collins, J.T., Lee-Yaw, J. A., Cannatella, D.C. (2007). "Phylogeny-based delimitation of species boundaries and contact zones in the trilling chorus frogs (Pseudacris)." Molecular Phylogenetics and Evolution, 44, 1068-1082. [link]

Moriarty, E.C., Cannatella D.C. (2004). “Phylogenetic relationships of the North American chorus frog (Pseudacris: Hylidae).” Molecular Phylogenetics and Evolution 30: 409-420 [link]

Platz, J. E., Forester, D. C. (1988). “Geographic variation in mating call among the four subspecies of the chorus frog: Pseudacris triseriata (Wied).” Copeia 1988:1062–1066 [link]

Powell, R., Conant, R., Collins, J. T. (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, 4th Edition. Houghton Mifflin Harcourt Publishing Company, New York, NY.

Schwartz, A.V. 1957. ‘Chorus frogs (Pseudacris nigrita LeConte) in South Carolina.’ American Museum Novitates 1838:1–12. [link]

White Jr., J. F., White, A. W (2002). Amphibians and Reptiles of Delmarva. Tidewater Publishers, Centreville, MD.

Yahner, R. H. (2003). ‘Terrestrial vertebrates in Pennsylvania: status and conservation in a changing landscape.’ Northeastern Naturalist 10: 343–360. [link]

Originally submitted by: Stephanie Menjivar (2021-03-20)
Description by: Stephanie Menjivar (updated 2021-03-20)
Distribution by: Stephanie Menjivar (updated 2021-03-20)
Life history by: Stephanie Menjivar (updated 2021-03-20)
Trends and threats by: Stephanie Menjivar (updated 2021-03-20)
Comments by: Stephanie Menjivar (updated 2021-03-20)

Edited by: Ann T. Chang (2021-03-20)

Species Account Citation: AmphibiaWeb 2021 Pseudacris kalmi: New Jersey Chorus Frog <> University of California, Berkeley, CA, USA. Accessed Jan 27, 2022.

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Citation: AmphibiaWeb. 2022. <> University of California, Berkeley, CA, USA. Accessed 27 Jan 2022.

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