The Cajun chorus frog (P. fouquettei) is a recently described species that is found in the American South. It was previously considered a member of the P. feriarum species complex. Recent work using mitochondrial DNA, advertisement calls, and, to a lesser extent, morphology revealed that P. fouquettei is indeed a separate species from P. feriarum (Lemmon et al. 2008).
Description: Cajun chorus frogs are relatively small with males attaining a maximum snout-vent length (SVL) of 30 mm and females attaining at least 27 mm SVL (Lemmon et al. 2008). The head is barely convex when viewed from above and is slightly narrower than the body. The snout tapers to a sharp point when viewed from the side. The upper jaw exceeds the tip of the lower jaw. The snout is long, with a rounded canthus rostralis and barely concave loreal region. Nostrils are slightly protuberant and are positioned two-thirds of the distance from the anterior of the eyes to the tip of the snout. Eyes are medium in size and do not protrude. Lips are moderately thick and do not flare. The supratympanic fold is thin and runs from the back of the eye tp above the tympanum (barely obscuring the upper edge of the tympanum), and then downward towards the arm insertion. Distance from the eye to the tympanum is equal to about two-thirds the diameter of the tympanum. Arms are robust and moderately long. There is no axillary membrane (membrane between body and limb at insertion). A slight skin fold is evident at the ulnar joint but no tubercles are present. A distinct fold of skin is seen on the dorsal surface of the wrist. Fingers are long and slender and the toe pads are only slightly wider than the fingers. The round tubercles on the pads are moderately large and are not bifid. There is a large almost bisected tubercle on the palm. Breeding males do not bear nuptial excrescences (used to grip the female during amplexus). There is no webbing between the digits of the hand. Hindlimbs are slender and moderately long with a well developed, flap-like, inner tarsal fold running the entire length of the tarsus and connecting to the inner metatarsal tubercle. No outer tarsal fold is present. The inner metatarsal tubercle is small, oval-shaped, and raised, while the outer metatarsal tubercle is smaller and conical. Toes are long and slender with toe pads slightly wider than the digits. Subarticular tubercles are large, round, and flattened. Proximal segments of the outer digits have a few indistinct supernumerary tubercles. On the feet, webbing only occurs basally between digits III-IV and IV-V. The cloaca lies near the mid level of the thighs with a short flap of skin that lies above the opening and partially covers it. The skin on the back is weakly granular while the ventral surface is robustly granular. The tongue, barely free behind, is heart-shaped with a small notch posterior. Two or three teeth are present on each vomerine process. In males, vocal slits extend along the posterior 2/3 of the tongue to the jaw angle. A single median subgular vocal sac is present in males. This vocal sac is greatly expandable (Lemmon et al. 2008).
Similar species: P. fouquettei can be distinguished from sympatric congeners in the south-central U. S. as follows: from P. crucifer by lacking an X-shaped dorsal pattern, having smaller terminal discs, being more terrestrial, and having a pulsed call (vs. an unpulsed single-note call in P. crucifer) ; from P. streckeri by being smaller and less robust and having terminal discs, and having a pulsed call (vs. an unpulsed single-note call in P. streckeri); and from P. clarkii by lacking green spots or green stripes on the dorsum, lacking an interorbital triangle, and having a call with a much slower pulse rate. P. fouquettei hybridizes with P. nigrita along the border between Louisiana and Mississippi (Gartside 1980) but outside of the contact zone can be distinguished by color pattern, with P. fouquettei having three brown longitudinal stripes or rows of spots on a pale tan or gray dorsum, and a white labial stripe (vs. comparatively darker broken dorsal stripes or spots in P. nigrita, and wider, dark brown to nearly black transverse bars on the hindlimbs) (Lemmon et al. 2008).
Coloration of live adults is light brown above with three darker brown stripes along the back. If stripes are not present there will be three sets of dark spots forming rows along the back, or some individuals will be patternless except for leg markings. The back can range from light gray to tan with a slight pinkish hue. There also may be gold flecking on the back. A bright iridescent white labial stripe extends beyond the eye to just behind the tympanum. The pupil is dark brown with a bronze-gold iris. There is also a wide reddish-brown stripe that extends laterally from the tip of the snout along the flank just anterior to the hindlimbs. Hindlimbs are tan to medium brown with dark brown transverse bars. Variation has been observed in the number (2-15) and intensity of the leg bars. The ventral surface is cream colored with occasional dark flecks and the throat is yellowish-brown (Lemmon et al. 2008).
Coloration of preserved specimens is similar to live coloration. However, in preserved individuals the white labial stripe is no longer iridescent and no pinkish hue or bronze flecking is apparent on the dorsal surface (Lemmon et al. 2008).
Tadpoles reach a length of 43 mm (Dundee and Rossman 1989). They usually have dark spots along the back and bicolored tail musculature. The tail has a dark stripe on each side of the pigmented area and freckled tail fins. A further description of tadpoles of this species can be found in Siekmann (1949) and photographs of tadpoles (referred to as P. triseriata) can be viewed in Trauth et al. (2004). Newly transformed frogs in Louisiana are quite small and only measure 8.5-13.5 mm SVL (Dundee and Rossman 1989).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: United States
U.S. state distribution from AmphibiaWeb's database: Arkansas, Louisiana, Missouri, Mississippi, Oklahoma, Texas
Pseudacris fouquettei is found throughout Louisiana, Arkansas, Eastern Texas, Eastern Oklahoma, Western Mississippi, and into extreme Southern Missouri (Lemmon et al. 2008). It is found in a variety of habitats from forested areas to open fields throughout the breeding season and frequently colonizes wet roadside ditches (Lemmon et al. 2008). The only habitat the species does not occupy within its range is the marshes of Southern Louisiana (Dundee and Rossman 1989). Little is known of the habitat utilized by Pseudacris fouquettei in the non-breeding season (Lemmon et al. 2008). However, since it is rarely seen above ground during non-breeding it is assumed that it must burrow underground (Dorcas and Gibbons 2008).
Life History, Abundance, Activity, and Special Behaviors
These mostly diurnal frogs are active throughout their breeding season. Breeding generally occurs from January through May (Lemmon et al. 2008), but depending on the temperature, breeding may commence as early as the end of October (Dundee and Rossman 1989). Breeding activity occurs from 4°-21°C, typically after rainfall (Lemmon et al. 2008). Breeding and courtship usually occur in shallow temporary pools and flooded fields where there is emergent vegetation (Dundee and Rossman 1989). Males sit concealed within the grasses to produce advertisement calls (Dundee and Rossman 1989).
The advertisement call of Pseudacris fouquettei generally resembles that of other chorus frogs. This call can be imitated by rubbing one's thumb along a stiff comb (Dundee and Rossman 1989). Although the call's average dominant frequency is similar for P. fouquettei and three parapatric congeners (3139 Hz in P. fouquettei vs. 2952-3079 Hz in the congeners), P. fouquettei has a slower call rate than P. feriarum and P. maculata, a higher duty cycle (call length/call period) than P. nigrita, an intermediate pulse number, and a longer call length than all three species (Lemmon et al 2008). It was shown ifor P. nigrita that most interactions between calling males were defensive with no aggressive territorial behavior observed (Martof and Thompson 1958).
Amplexus is axillary. Females lay anywhere from 500 to 1,500 eggs in small soft clusters attached to vegetation, usually grass stems (Dundee and Rossman 1989). These eggs will hatch within a few days, depending upon the water temperature (Dorcas and Gibbons 2008). The tadpoles remain in the water until they fully metamorphose (48 to over 80 days) (Dorcas and Gibbons 2008). The newly transformed frogs usually stay close to the water body for a short time after that (Dorcas and Gibbons 2008).
Adults usually disperse within 200 m of the breeding pool after breeding. They feed on small invertebrates like ants, beetles, and flies. Tadpoles most likely feed on algae and other detritus from grass stems and other objects. Tadpoles are likely consumed by large diving beetles and fishing spiders. Adults are probably heavily consumed by garter snakes, and ribbon snakes. They are probably also consumed by birds, mammals, water snakes, and turtles. No escape or defense behavior has been observed for Pseudacris fouquettei (Dorcas and Gibbons 2008).
Trends and Threats
Pseudacris fouquettei is currently recognized as a species of least concern by the International Union for Conservation of Nature (IUCN; Hammerson 2008). The overall trend of the population is thought to be stable or declining slightly throughout its range, with the total adult population size assumed to exceed 100,000 (Hammerson 2008). This species tolerates some environmental degradation. It also occupies many protected areas. Localized impacts are possible due to increased urbanization, agriculture, and logging (Hammerson 2008). In addition, Rothermel et al. (2008) reported that some Louisiana specimens were infected with the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd).
Possible reasons for amphibian decline
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Pseudacris fouquettei was previously regarded as part of a wide-ranging chorus frog complex. It was previously called Pseudacris triseriata feriarum and most recently P. feriarum. The specific epithet “fouquettei” is in reference to Martin J. “Jack” Fouquette, Jr., who studied chorus frogs in the 1960s and 1970s.
This species is known to hybridize with P. nigrita within a narrow range in Southeastern Louisiana and Southwestern Mississippi (Gartside 1980). The small size of this hybrid zone suggests that the hybrids are less fit than the parental species (Lemmon et al. 2007). The presence of these hybrids and a survey of mitochondrial DNA clearly show that Pseudacris fouquettei and Pseudacris nigrita are sister species (Lemmon et al. 2007). Unlike P. nigrita, P. fouquettei is not restricted to pine forest (Lemmon et al. 2008).
Dorcas, M. and Gibbons, W. (2008). Frogs and Toads of the Southeast. University of Georgia Press, Athens, GA.
Dundee, H. A., and Rossman, D. A. (1989). The Amphibians and Reptiles of Louisiana. Louisiana State University Press, Baton Rouge, LA.
Gartside, D. F. (1980). ''Analysis of a hybrid zone between chorus frogs of the Pseudacris nigrita complex in the Southern United States.'' Copeia, 1980(1), 56-66.
Hammerson, G. 2008. Pseudacris fouquettei. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. www.iucnredlist.org. Downloaded on 04 December 2009.
Lemmon, E. M., Lemmon, A. R., Collins, J. T., Cannatella, D. C., and Lee-Yaw, J. A. (2008). ''A new North American chorus frog species (Amphibia: Hylidae: Pseudacris) from the south-central United States.'' Zootaxa, (1675), 1-30.
Lemmon, E. M., Lemmon, A. R., and Lee-Yaw, J. A. (2007). ''Phylogeny-based delimitation of species boundaries and contact zones in the trilling chorus frogs (Pseudacris).'' Molecular Phylogenetics and Evolution, (44), 1068-1082.
Martof, B. S. and Thomspon, E. F. Jr. (1958). ''Reproductive behavior of the chorus frog, Pseudacris nigrita.'' Behaviour, 13(3/4), 243-258.
Rothermel, B. B., Walls, S. C., Mitchell, J. C., Dodd, C. K. Jr., Irwin, L. K., Green, D. E., Vazquez, V. M., Petranka, J. W., and Stevenson, D. J. (2008). ''Widespread occurrence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in the southeastern USA .'' Diseases of Aquatic Organisms, 82, 3-18.
Siekmann, J.M. (1949). A Survey of the Tadpoles of Louisiana. M.S. Thesis. Tulane University, New Orleans, LA.
Written by Ray Schmidt (rschmidt AT tulane.edu), Tulane University
First submitted 2011-03-28
Edited by Kellie Whittaker (2011-06-27)
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