Pseudacris fouquettei, Lemmon, Emily Moriarty, Lemmon, Alan R., Collins, Joseph T. & Cannatella, David C., 2008

Lemmon, Emily Moriarty, Lemmon, Alan R., Collins, Joseph T. & Cannatella, David C., 2008, A new North American chorus frog species (Amphibia: Hylidae: Pseudacris) from the south-central United States, Zootaxa 1675, pp. 1-30 : 4-14

Pseudacris fouquettei sp. nov.

( Figs. 2 and 3 )

Cajun Chorus Frog

Holotype: ( Fig. 2) TNHC 62265 (Texas Natural History Collection; field no. ECM 0029), adult male from the United States: Louisiana: East Baton Rouge Parish: (NW of Baywood on Lee Price Road, 1.4 mi W of jct. with SR 37; N30.7147 W90.8919), collected by Emily Moriarty Lemmon and David C. Cannatella on 11 March 2001.

Paratypes: TNHC 62266–62267, same data as holotype and TNHC 63471–63479, same data as holotype except collected 21 February 2003 between 0.3–0.6 mi W of jct. with SR 37 on Lee Price Road.

Etymology: The specific epithet is a patronym for Martin J. “Jack” Fouquette, Jr., who studied Pseudacris in the 1960s and 1970s. His extensive unpublished field data were instrumental in efforts to elucidate the species diversity of chorus frogs.

Synonymy: A detailed history of Pseudacris nomenclature is available on the Amphibian Species of the World website ( Frost 2007).

Diagnosis: Pseudacris fouquettei is distinguished from other chorus frogs by 1) genetic data ( Lemmon et al. 2007b; Gartside 1980), 2) geographic distribution ( Fig. 1 ), 3) advertisement call ( Figs. 4–6 ), and 4) to a lesser degree by morphological data ( Figs. 6 –7). This small slender species, with a subacuminate snout, has a dorsal pattern of three medium to dark brown longitudinal stripes or rows of spots on a pale tan or gray ground color; a white labial stripe is present.

Pseudacris fouquettei can be distinguished from three broadly sympatric chorus frogs in the south-central United States using color pattern, morphology, and the terminal discs on the digits. Pseudacris crucifer typically has an “X” pattern on the dorsal surface, larger terminal discs, and is more arboreal. Pseudacris streckeri is larger and heavier-bodied and lacks terminal discs. In addition, both of these species have unpulsed singlenote advertisement calls compared to the pulsed call of P. fouquettei . Pseudacris clarkii typically has green spots or stripes on the dorsal surface, an interorbital triangle, and produces a much faster pulse-rate call ( Conant and Collins 1998; E. Moriarty Lemmon, unpub. data).

Pseudacris fouquettei can also be distinguished from three taxa with parapatric distributions: P. feriarum , P. maculata , and P. n i g r i t a ( Fig. 1 ; Lemmon et al. 2007b). Genetic data show that Pseudacris fouquettei is not closely related to the species in which it was formerly included ( P. feriarum ) or to P. maculata or P. triseriata . The new species instead forms the sister clade to P. nigrita ( Fig. 8 ; Lemmon et al. 2007b). Pseudacris fouquettei (referred to as P. triseriata feriarum by Gartside [1980]) is known to hybridize with P. nigrita in a narrow <20 km zone in the Pearl River floodplain along the border between Louisiana and Mississippi ( Gartside 1980). The two species are fixed for alternative alleles at two or more allozyme loci outside the hybrid zone, however, indicating species-specific differences between these taxa ( Gartside 1980). In addition, these taxa differ at 38 diagnostic SNPs in the 12S/16S mitochondrial gene region (27 P. fouquettei and 17 P. n i g r i t a were examined; Lemmon et al. 2007b). Average pairwise sequence divergence between the two species is comparable to genetic distances of other Pseudacris species pairs ( Fig. 8 ; GTR+G+I corrected p-distances for the 12S/16S mitochondrial region, with parameter settings derived from the mean of the posterior distribution from the Lemmon et al. [2007b] Bayesian analysis). Pseudacris fouquettei and P. nigrita also show a sharp cline in color pattern across this contact zone and are easily distinguished using this character outside of the zone ( Gartside 1980; EML unpub. data).

Advertisement call data indicate that P. fouquettei differs from the three parapatric species with respect to several variables. The new species has a slower call rate than P. feriarum and P. m a c u l a t a (0.34± 0.06 s.d. vs. 0.49±0.05 and 0.42±0.07 calls/sec, respectively), a higher call duty cycle than P. nigrita (0.36±0.05 vs.0.31±0.04), a longer call length than all three species (1115.42±150.34 vs. 745.95±79.25, 906.56±127.48, and 892.73±106.43 ms, respectively), and an intermediate pulse number between P. feriarum , P. maculata , and P. nigrita (13.07±1.63 vs. 17.04±2.25, 17.09±1.64 and 9.56±1.67, respectively). There is broad overlap among species with regard to dominant frequency ( Figs. 4 –5; Table 1).

Holotype P. fouquettei P. feriarum P. nigrita P. maculata (n =26) (n =19) (n =19) (n=15)

DF 3273.05 3138.80±205.79 2952.28±312.93 3044.63±156.84 3078.81±135.96 2845.97–3712.94 2583.98–3583.74 2767.02–3294.58 2855.63–3283.81

CDC 0.37 0.36±0.05 0.38±0.05 0.31±0.04 0.37±0.04

0.26–0.44 0.31–0.49 0.25–0.40 0.31–0.44

CL 910.31 1115.42±150.34 745.95±79.25 906.56±127.48 892.73±106.43 867.15–1554.53 599.08–908.53 701.39–1161.68 728.39–1183.05

CR 0.41 0.34±0.06 0.49±0.05 0.34±0.05 0.42±0.07

0.14–0.43 0.42–0.59 0.26–0.46 0.24–0.55

PN 13.50 13.07±1.63 17.04±2.25 9.56±1.67 17.09±1.64

9.93–15.69 12.45–22.43 6.40–12.92 13.45–20.00 Principal component analyses of call variables indicate that P. fouquettei does not overlap with P. feriarum along PCI (explains 47% of variance), which has high loadings of call rate and pulse number. The new species overlaps to a small degree with P. maculata and to a greater degree with P. n i g r i t a along this axis. Pseudacris fouquettei overlaps with all three species along PCII (explains 27% of variance), which has high loadings of call duty cycle and call length ( Fig. 6 ; Table 2 ).

In congruence with previous studies, Pseudacris fouquettei overlaps morphologically with the parapatric taxa P. feriarum and P. nigrita . These three species are morphologically distinct from their more distant relative, P. maculata , with respect to head width, head length, eye width, tibia length, and femur length (Fig. 7). Pseudacris fouquettei is more similar to its sister species, P. nigrita , in terms of head width and femur length, more similar to P. feriarum with regard to head length, intermediate between the two species with respect to snout angle and foot length, and nearly identical to both species in terms of snout length, eye width, tympanum diameter, and tibia-fibula length (Fig. 7; Table 3).

Multivariate analyses of morphometric data indicate that P. fouquettei is essentially identical to P. f e r i - arum and P. nigrita along PC1 (explains 53% of variance), which is dominated by head size and leg length variables. The three species are distinct from P. m a c u l a t a along this axis. Pseudacris fouquettei is intermediate between P. feriarum and P. nigrita , however, along PC2 (explains 18% of variance), which is dominated by snout angle and foot length ( Fig. 6 ; Table 4 ).

FIGURE 5. Box and whisker plots (median = central black bar, boxes = 25th–75th quartiles, whiskers = maximum and minimum values after excluding outliers) showing advertisement call variation among Pseudacris fouquettei (fou), P. feriarum (fer), P. nigrita (nig), and P. maculata (mac). Five variables are presented: call rate, call length, dominant frequency, pulse number, and call duty cycle. Individuals analyzed are listed in Appendix 2.

Holotype P. fouquettei P. feriarum P. nigrita P. maculata (n =117) (n =202) (n =78) (n =74)

SVL 27.38 26.39±1.71 25.54±1.90 25.73±1.75 24.35±2.80 22.20–29.79 19.98–30.28 21.26–29.50 19.95–30.56 SA 1.04 0.99±0.05 1.02±0.06 0.96±0.05 0.96±0.06 0.84–1.13 0.81–1.20 0.86–1.08 0.79–1.11 HW 9.30 8.72±0.63 8.81±0.63 8.56±0.61 7.36±1.07 7.01–10.14 6.67–10.18 6.80–10.15 5.34–10.03 HL 9.36 9.17±0.54 9.07±0.62 9.27±0.57 7.99±0.99 7.74–10.44 7.36–10.73 7.97–10.70 6.28–10.21 TD 1.72 1.34±0.20 1.36±0.20 1.30±0.13 1.22±0.23 0.77–1.80 0.81–1.83 1.01–1.62 0.87–1.81 EW 3.07 2.88±0.25 2.91±0.27 2.93±0.23 2.48±0.29 2.18–3.55 2.23–3.65 2.35–3.55 1.92–3.18 Snout 2.29 2.48±0.25 2.41±0.26 2.49±0.24 2.17±0.33 1.86–2.97 1.64–3.05 1.94–3.16 1.32–2.95 FeL 13.14 11.69±0.94 11.96±1.02 11.68±0.86 9.75±1.46 9.38–14.18 9.33–14.74 9.38–13.68 7.73–13.44 TL 14.07 13.08±0.91 13.05±1.04 12.87±0.98 10.14±1.50 10.97–15.11 10.42–15.37 10.82–15.06 8.08–13.50 FoL 13.60 12.87±0.92 12.21±1.04 12.94±1.08 11.60±1.59 10.14–14.85 9.84–15.17 10.54–15.54 8.97–15.36 The color pattern of P. fouquettei closely resembles that of P. feriarum in terms of the three longitudinal stripes along the dorsal surface, although there is high inter-population variation in this character ( Fig. 3 ). Pseudacris fouquettei can be easily distinguished from P. n i g r i t a, however, based on color pattern. The latter species has generally darker markings including a broken stripe or spotted pattern on the dorsal surface and wider, darker (tending to black), transverse bars on the legs ( Figs. 2 and 3 ).

Description: Male Pseudacris fouquettei attain a maximum snout-vent length of 30 mm, and females reach at least 27 mm. The head is slightly narrower than the body, and the top of the head is barely convex. In dorsal profile, the snout is acuminate and in ventral profile, it projects well beyond the tip of the lower jaw. The snout is long with slightly protuberant nostrils situated at a point about two-thirds of the distance from the anterior corner of the eye to the tip of the snout. The eyes are of moderate size and not protuberant. The canthus rostralis is rounded, and the loreal region is barely concave; the lips are moderately thick and not flared. A thin supratympanic fold extends posteriorly from the eye, above the tympanum, and downward to a point above the insertion of the arm. The fold barely obscures the upper edge of the tympanum, which otherwise is distinct and separated from the eye by a distance equal to about two-thirds of the diameter of the tympanum.

The arms are moderately long and robust; an axillary membrane is absent. A slight ulnar fold is present, with no rows of tubercles, and a distinct dermal fold is present on the dorsal surface of the wrist. The fingers are long and slender and bear discs that are only slightly wider than the fingers. The subarticular tubercles are moderately large and round, and none are bifid. The supernumerary tubercles are absent. A large almost bifid palmar tubercle is present. The prepollex is not enlarged and in breeding males does not bear a nuptial excrescence. No webbing is present on the hands. The legs are of moderate length and slender. A well-developed, flaplike inner tarsal fold extends the full length of the tarsus and connects to the inner metatarsal tubercle. An outer tarsal fold is lacking. The inner metatarsal tubercle is small, elliptical, and elevated. A smaller, conical outer metatarsal tubercle is present. The toes are long and slender; the small toe discs are slightly wider than the digits. The subarticular tubercles are large, round, and flattened in profile. A few supernumerary tubercles are barely evident on the proximal segments of the outer digits. The toes are webbed only basally between digits III and IV and between IV and V.

FIGURE 7. Box and whisker plots (median = central black bar, boxes = 25th–75th quartiles, whiskers = maximum and minimum values after excluding outliers) showing morphological variation among Pseudacris fouquettei (fou), P. f e r i - arum (fer), P. nigrita (nig), and P. m a c u l a t a (mac). Nine variables are presented: residual head width, residual head length, residual snout length, residual snout angle, residual eye width, residual tympanum diameter, residual tibia-fibula length, residual femur length, and residual foot length. Individuals analyzed are listed in Appendix 1.

The cloacal opening is directed posteriorly near the mid level of the thighs; a short transverse flap lies dorsal to the opening, and partially covers it. The skin on the dorsum is weakly granular, whereas that on the venter is strongly granular. The tongue is cordiform, shallowly notched posteriorly, and barely free behind. The dentigerous processes of the vomers are small rounded elevations that are widely separated medially and lie between the ovoid choanae. Two or three teeth are present on each process. The short elliptical vocal slits extend along the posterior two-thirds of the tongue to the angle of the jaws. The vocal sac is single, median, subgular, and greatly distensible.

Measurements of holotype: Adult male, morphometric data: SVL 27.38; SA 1.04; HW 9.30; HL 9.36; TD 1.72; EW 3.07; Snout 2.29; FeL 13.14; TL 14.07; FoL 13.60 mm; advertisement call data: DF 3273.05 Hz; CDC 0.37; CL 910.31 ms; CR 0.41 calls per sec; PN 13.50; genetic data: mitochondrial haplotype of the Pseudacris fouquettei clade ( Lemmon et al. 2007b).

Color in preservative: The general coloration of Pseudacris fouquettei is light brown above with three darker brown stripes or three sets of elongate spots forming rows on the back. The dorsal surface ranges from light gray to tan. The markings on the back and transverse bars on the limbs vary from medium to dark brown. There is a dark brown to reddish-brown stripe from the nostril to the eye, which extends to the mid or posterior flank region. A white to cream labial stripe is present, and extends beneath the eye to just posterior to the tympanum. The venter is creamy white and may have some brown flecking in the pectoral and mid abdominal region. The eye has a dark pupil with a bronze-gold iris.

Color in life: In life, the coloration is similar to that in preservative except the labial stripe is a bright iridescent white, the ground dorsal color may have a very slight pinkish hue, and the dorsal surface may have occasional brassy or gold flecking. Based on color photographs before preservation, paratypes TNHC 63471 and TNHC 63473 are tan to medium brown on the dorsal surface with three dark brown stripes that run longitudinally down the back of the frog. A broad dark reddish brown stripe runs laterally from the tip of the snout through the eye and tympanum to just anterior to the rear legs. A narrow bright white line runs laterally from the tip of the snout to the posterior end of the jaw just below the brown lateral stripe. Front and rear legs have dark brown transverse bars on a tan to medium brown background. The ventral surface is cream with several dark flecks. The throat is yellowish-brown.

Tadpoles: The tadpoles of this species have been described by Siekmann (1949; referred to as Pseudacris triseriata feriarum ). Trauth et al. (2004) show multiple photographs of P. fouquettei tadpoles (referred to as P. triseriata ) at different developmental stages.

Variation: There is marked variation in color pattern types in our sample of twelve Pseudacris fouquettei from the type locality (East Baton Rouge Parish, Louisiana). Four exhibit a strong three-stripe pattern on the dorsal surface (TNHC 62267, 63471, 63477, and 63478), two show a three-stripe pattern with dark dots bounding the stripes (TNHC 63473 and 63475), four show a broken three-stripe pattern (TNHC 62265, 62266, 63472, and 63479), and two are patternless, except for markings on the legs (TNHC 63474 and 63476). An interorbital triangle is not present in any specimens. Dark transverse bars are present on the legs and vary in number from 2 to 15 among specimens. A dark brown stripe runs laterally from anterior to the nares to mid-flank, and a white labial stripe is present on all specimens. The ventral surfaces are generally cream, but some specimens have venters with scattered flecks of gray pigment. The vocal sac area is yellowish-orange with dark gray pigment (in males).

Other Pseudacris fouquettei populations are similar in color pattern, except that the stripe pattern is more consistent. In ten specimens from Craighead Co., Arkansas, all except one exhibit the solid three-stripe pattern (TNHC 62255–62264, not TNHC 62259, which shows a faint broken-stripe pattern). In twelve specimens from Newton Co., Texas, all specimens show a strong three-stripe pattern (TNHC 20691–20696 and TNHC 20698–20704; Appendix 1).

Ecology and natural history: Pseudacris fouquettei is a winter or early spring breeder that can be heard chorusing in temporary bodies of water from January to May. Breeding activity depends on amenable temperatures (4°C to 21°C; nocturnal temperature of 10–18°C is optimal) and recent rainfall. Pseudacris fouquettei congregate to breed in ephemeral pools and ponds in a variety of habitats, ranging from forested areas to open fields. The species has successfully colonized wet roadside ditches throughout its range. Little is known about the activity of the species outside of the breeding season. Frogs disperse from breeding sites and presumably forage on small invertebrates like other trilling chorus frogs ( Whitaker 1971) and range within an area of about 200 m from the breeding pool ( Kramer 1973, 1974). Pseudacris fouquettei is not ecologically limited to pine forest, as is its sister species, P. nigrita . Rather, the new species appears to tolerate a much broader range of environmental conditions.

Distribution: Pseudacris fouquettei is distributed along the coast of the Gulf of Mexico from western Mississippi, Louisiana, and eastern Texas north to eastern Oklahoma (nearly to Kansas), Arkansas, and barely into southern Missouri ( Fig. 1 ; Lemmon et al. 2007b).

Figures

FIGURE 1. Distributions of Pseudacris feriarum, P. fouquettei, P. maculata, and P. nigrita in the southern United States based on genetic data (Lemmon et al. 2007 b). Symbols indicate populations included in genetic analyses. The type locality of P. fouquettei is denoted with a star. Capital “ C ” s indicate populations analyzed for advertisement calls. Populations analyzed for morphometric data are not shown (see Appendix 1).

FIGURE 3. Photographs of Pseudacris feriarum, P. fouquettei, P. maculata, and P. nigrita in life. Specimens are described with localities and museum numbers from left to right: P. nigrita: Calhoun Co., Florida TNHC 63211 and Barnwell Co., South Carolina TNHC 62205; P. fouquettei: Marion Co., Mississippi TNHC 63600 and Craighead Co., Arkansas TNHC 62259; P. feriarum: Calhoun Co., Florida TNHC 63319 and Johnson Co., North Carolina TNHC 63564; P. m a c u l a t a: Fillmore Co., Minnnesota TNHC 63612 and Douglas Co., Kansas TNHC 62378. Photos by EML except TNHC 63612 was photographed by Suzanne L. Collins.

FIGURE 4. Advertisement calls of Pseudacris nigrita (first row), P. fouquettei (second row), P. feriarum (third row), and P. maculata (fourth row). Individuals were recorded within ~ 2 ° C of each other at 11.6, 12.6, 13.8, and 11.7 ° C, respectively. Oscillograms (10 sec and 1.5 sec) are shown in columns A and B, spectrograms in column C, and power spectra in column D. Numbered calls in A indicate different individuals calling in sequence. A single call is represented in B – D. Units are as follows: amplitude (volts), time (seconds), and frequency (kilohertz).

FIGURE 6. Multivariate variation in morphology and advertisement calls within and among Pseudacris feriarum, P. fouquettei, P. m a c u l a t a, and P. nigrita along the first two principal component axes. Representatives of each species are enclosed by polygons. Analyses of morphological data were based on the nine variables in Fig. 7. Analyses of call data were based on the five variables in Fig. 5. Prior to analysis, morphological variables were averaged by population, such that each point on the graph represents a population. In contrast, points on the advertisement call graph represent individuals.

FIGURE 8. Phylogeny of the trilling chorus frogs (clade within Pseudacris) based on Lemmon et al. (2007 b). Also shown are within- and between-species average pairwise genetic distances (GTR + G + I corrected p-distances) for the 12 S / 16 S mitochondrial region, expressed as percentages. Pseudacris maculata and P. clarkii are represented with a single branch because these species are not reciprocally monophyletic.

Tables

TABLE 2. Loadings for the first four principal components from the multivariate analysis of advertisement call variables.

	I	II	III	IV
DF	-0.267	0.377	0.867	0.187
CDC	0.426	0.583	-0.024	-0.502
CL	-0.352	0.652	-0.370	-0.053
CR	0.600	-0.107	0.304	-0.274
PN	0.513	0.286	-0.138	0.797
Eigenvalues	2.327	1.338	0.838	0.412
Percent of Variance	46.538	26.757	16.753	8.245
Cumulative Percent	46.538	73.294	90.047	98.292

TABLE 4. Loadings for the first four principal components from the multivariate analysis of morphometric variables.

	I	II	III	IV
Residual HW	0.419	-0.225	-0.106	-0.201
Residual HL	0.393	0.206	-0.205	0.061
Residual TD	0.191	-0.298	0.699	0.536
Residual EW	0.311	0.111	-0.361	0.620
Residual SL	0.318	0.281	0.448	-0.144
Residual FeL	0.408	-0.096	-0.169	-0.143
Residual TL	0.421	0.013	-0.104	0.045
Residual FoL	0.191	0.616	0.284	-0.283
Residual SA	0.237	-0.582	0.085	-0.402
Eigenvalues	4.757	1.590	0.934	0.653
Percent of Variance	52.853	17.667	10.376	7.253
Cumulative Percent	52.853	70.520	80.896	88.150