zootaxa, acris (anura, hylidae)

1104

Accepted by S. Carranza: 8 Oct. 2005; published: 5 Jan. 2006 1

ZOOTAXAISSN 1175-5326 (print edition)

ISSN 1175-5334 (online edition)Copyright © 2006 Magnolia Press

Zootaxa 1104: 1–21 (2006) www.mapress.com/zootaxa/

An evaluation of the subspecies Acris crepitans blanchardi (Anura, Hylidae)

MALCOLM L. McCALLUM 1 & STANLEY E. TRAUTH2

1 Biological Sciences Program, Texas A&M University-Texarkana, Texarkana, TX 75501, USA([email protected])2 Department of Biological Sciences, Arkansas State University, State University, AR 72467, USA

([email protected])

Abstract

We investigated the validity and distribution of the subspecies Acris crepitans blanchardi.Currently Acris crepitans contains three subspecies: the northern cricket frog (A. c. crepitans),Blanchards cricket frog (A. c. blanchardi) and the coastal cricket frog (A. c. paludicola). Weexamined the diagnostic characters of 1441 specimens from the center of the range (Arkansas,Missouri, and Mississippi), 161 specimens from the extreme northwest portion of this species range(South Dakota and Nebraska), and 85 from the extreme southeast portion of the species range(Florida and Georgia). Discriminate analysis was applied to the tabulated data and no significantdifferences between portions of the range could be discerned. No concrete evidence was found tosupport designation of specimens from South Dakota and Nebraska or from Smallens Cave (originof the type specimen) as A. c. blanchardi. This information places the subspecies A. c. blanchardiin a status of doubtful validity suggesting that no delineation between A. c. blanchardi and A. c.crepitans should be made at this time.

Key words: Acris crepitans blanchardi, A. crepitans, Blanchards Cricket Frog, subspecies

Introduction

The term subspecies came into use during the 19th century replacing the term variety.Mayr (1969) defined a subspecies as “An aggregate of phenotypically similar populationsof a species, inhabiting a geographic subdivision of the range of a species, and differingtaxonomically from other populations of the species.”

Early authors were often indiscriminant with their use of this category (Mayr, 1969)resulting in classification problems for modern day biologists.

McCALLUM & TRAUTH2 © 2006 Magnolia Press

1104ZOOTAXA Currently Acris crepitans contains three subspecies: the northern cricket frog (A. c.

crepitans), Blanchards cricket frog (A. c. blanchardi) and the coastal cricket frog (A. c.paludicola). The currently accepted intergrade zone for the species in Arkansas isdesignated as a line extending from the northeast to the southeast corner, roughlyfollowing the borders between the highland and lowland regions of the state (Trauth et al.,2004). Acris c. blanchardi is supposedly found north of this line (Trauth et al., 2004),whereas A. c. crepitans is found south of this line (Fig. 6).

Acris c. blanchardi is discerned from A. c. crepitans based on the presence of a suite ofcharacters (Harper, 1947). Acris c. blanchardi possesses warts on its snout (Fig. 1),slightly greater snout-vent length (SVL; male SVL = 24.1 mm, female SVL = 29.2 mm),body mass two times that of A. c. crepitans (BM; male BM = 1.3 g, female BM = 2.2 g),areola on the chest and abdomen (Fig. 2), a pectoral fold present (Fig. 3), webbingextending to the last digit of the fourth toe (Fig. 4), longer tibiotarsus length (male TL =14.4 mm, female TL = 17.0 mm), and the presence of a leg stripe not dorsally bordered bya light area (Fig 5). Harper (1947) indicated that the leg stripe is the most diagnostic of thecharacters.

The type specimen for A. c. blanchardi (No. 26,607) is housed at the CarnegieMuseum of Natural History (Pittsburg, PA) and was collected near Smallens Cave(Christian County, Missouri). All measurements were based on the type specimen and twotopotypes from the same location. Average weights and measurements were also obtainedfrom five adult males and 10 adult females from Tulsa County, Oklahoma. Harper (1947)remarked that the list of specimen numbers for specimens examined in his study was to bepublished at a later date, but this list could not be found in the herpetological literaturedespite extensive searching of BioAbstracts, Zoological Record, Current Contents,Science Citation Index, and Wildlife Abtracts. This information appeared to be lost withhis death in 1998 (Holliday, reference date unavailable).

The only morphometric taxonomic review of Acris was a limited species-levelinvestigation, comparing A. gryllus to A. crepitans (Neill 1950). That study was limited tospecimens from Georgia and Florida. Almost one third of the intergradation zone betweenA. c. crepitans and A. c. blanchardi occurs in Arkansas and has not been delineated sincethe description of A. c. blanchardi. This fact combined with the subspecies decline(Weller and Green, 1997; Hay, 1998; Lannoo, 1998) and extirpation (Anonymous, 1998)in areas of North America clearly necessitates a reexamination of the range and taxonomicstatus of A. c. blanchardi in Arkansas and other parts of its range. Our study evaluateswhether the subspecific characters are valid and if any observed changes in subspecificdistributions can be explained by northward advances in the range of A. c. crepitans sincethe description of A. c. blanchardi.

© 2006 Magnolia Press 3ACRIS CREPITANS BLANCHARDI

1104ZOOTAXAMethods

Subspecific characters were examined on 1441 specimens housed in the Arkansas StateUniversity Museum of Zoology herpetology collection (a sample representing everyspecimen deposited from its inception through December 2000). An additional five malesand one female were collected from a stream adjacent to Smallens Cave (Christian County,Missouri). Specimens (n = 161) from Nebraska and South Dakota were borrowed fromthe Nebraska State Museum (Lincoln, NB). Georgia and Florida (n = 95) specimens wereborrowed from the Georgia Museum of Natural History (Athens, GA) for additionalcomparisons. Nebraska animals originated from within the northern-most two rows ofcounties in the state. South Dakota animals originated from the southeastern counties (allcounties in the species range) in the state. Florida specimens originated from all northernFlorida counties in the limited range of this species in the state, and Georgia specimens alloriginated from the southern ¼ of this state.

Harper (1947) did not precisely define many of the characters used to describe A. c.blanchardi. For example, refers to characteristics such as “greater bulk”, “somewhatwider snout”, “warts on snout”, and “somewhat more variable in color”. Because of this,we produced definitions to objectively classify characteristics with generousinterpretations of his descriptions. If warts were present cranial to a line placed adjacent tothe caudal terminus of the eyes and perpendicular to the caudo-cranial axis, this wasdefined as a Blanchardian characteristic (Fig. 1). Areola were designated to be present ifone or more black spots were present on the abdomen, gular, or pectoral areas (Fig. 2).Any line extending between the axial regions was termed a pectoral fold (Fig. 3). If atleast one of the webbings on either side of the fourth digit met the last joint of that toe, itwas defined as Blanchardian (Fig. 4). If at least one of the hind limbs possessed a legstripe not dorsally bordered by a light area, it was termed a Blanchardian character (Fig.5).

FIGURE 1. Photograph of A. crepitans from Arkansas with warts located cranial to the caudalterminus of the eyes (note line). The arrows point to warts.FIGURE 2. Ventral view of A. crepitans from Arkansas with areola on the abdomen.

1 2


1104ZOOTAXA Tibiotarsus length was measured from 375 frogs, but was not used for subspecies

identification due to multicollinearity issues. Snout-vent length (SVL) was measured withvernier calipers, and BM was gathered using an electronic digital analytical balance.Color patterns were not used in this study because of the highly variable nature of colorwithin this species (Gray 1983, Gorman and Gaines 1987). The measurement of the“whole hind foot” was disregarded because of difficulties identifying individuals withregenerated and damaged toes, and because Nevo (1973) provided convincing evidencethat foot webbing is a positive temporal and spatial correlate with temperature,precipitation, and the number of sympatric anuran species (not subspecies designations,per se).

FIGURE 3. Ventral views of A. crepitans from Arkansas with (A) and without (B) a pectoral fold.

While defining these methods, every effort was made to bias the data toward thepresence of Blanchardian characters at the expense of those for A. c. crepitans. Both SVL


1104ZOOTAXAand BM were compared between Nebraska-South Dakota and Georgia-Florida samples

using a Mann-Whitney U test.

FIGURE 4. The variation in degrees of foot webbing in A. crepitans in Arkansas. Arrows point toterminus of webbing and the line shows the distal phalange joint. A. Both webs are proximal to thedistal phalange joint. B. Both webs are distal to the distal phalange joint. C. One web is distal andone web proximal to the distal joint. D. Both webs meet the distal phalange joint. E. One webmeets the distal phalange joint, whereas the other does not.

Discriminant function analysis (DFA; Harris 2001, Huberty 1975, 1984) is amultivariate statistical technique that can be used to separate groups based on a series ofcharacteristics. DFA was performed using SPSS 10.0 to compare the five primary present/absent Blanchardian characteristics on 1697. A DFA was used to compare three broadregions of A. crepitans range: 1) the central range (1441 animals originating fromArkansas, Mississippi, and Missouri), 2) the northwest range (161 animals from Nebraska


1104ZOOTAXA and South Dakota), and 3) the southeast range (95 animals from Georgia and Florida). In

this analysis, extreme differences between ranges might suggest a new species or validatethe subspecies designation. A situation in which the northwestern range is maximallydifferent from the southeastern range but is similar to the central range might indicate thatwe had misplaced intergrade zone and further analysis may be required or that the range ofA. c. blanchardi moved since its description (possibly due to climate change).

A DFA was used to compare the northwest range to the southeast range withoutinclusion of the specimens from the central region. Misplacements in this analysis wouldsuggest the intergrade zone was mispositioned and needs realignment.

FIGURE 5. Hind legs showing variation in dorsal bordering of the leg stripe in A. crepitans fromArkansas. A. Presence of dorsal light area/leg stripe not present on one leg, questionably present onthe other. B. Light area present on both legs. C. Leg stripe discontinuous and light area gradatesinto dorsum background pattern, presence questionable.


1104ZOOTAXAA DFA was utilized to compare all specimens from north of the currently accepted

intergrade zone to those originating south of it, and to those originating from within thezone of intergradation. If specimens from the intergrade zone were misplaced in eithersubspecies, the zone must be repositioned.

A DFA was used to analyze specimens from within the central range (area B on Fig.6). In this analysis specimens from northwest Arkansas and southern Missouri (area A onFig. 6), southeast Arkansas and Mississippi (area C on Fig. 6), and those from thecurrently accepted intergrade zone (area B on Fig. 6) were compared. If specimens fromarea A were correctly classified as A. c. blanchardi and specimens from Area C werecorrectly classified as A. c. crepitans, this would support the subspecific designation of A.c. blanchardi. If the currently placed intergrade zone (area A, Fig 6) could not bediscerned from one of the two subspecies ranges, this would suggest that the currentlyplaced intergrade zone was incorrectly positioned and must be adjusted. Additional DFAswere utilized to further refine the relationships between three regions and the intergradezone for this species.

FIGURE 6. Distribution of Acris crepitans with various numbers of A. c. blanchardi characters inArkansas. The star denotes Christian County, Missouri, the source of A. c. blanchardis holotype.Pie charts indicate the proportion of specimens from that county possessing blanchardian charactersas designated on the key. The area located between the diagonal lines approximates the intergradezone (B) between A. c. blanchardi to the north (A) and A. c. crepitans to the south (C) of these lines.No pie charts occur under the labels for these three regions.


1104ZOOTAXA

FIGURE 7. Distributions of A. c. blanchardi and A. c. crepitans in Arkansas. Counties with

individuals having (A) 4 or more Blanchardian characters (in yellow) representing Acris crepitans

Blanchardi, (B) with 2-3 Blanchardian characters (in blue) representing subspecies intergradations,

(C) 1 or fewer Blanchardian characters (in blue) representing A. c. crepitans.


1104ZOOTAXAThe total number of Blanchardian characters for each frog was tabulated. Any frogs

with three or more Blanchardian characters were designated as A. c. blanchardi. Then thefraction of A. c. blanchardi to A. c. crepitans for each county was tabulated and mappedusing ArcView GIS 3.2. Trends analysis was used to identify SVL and BM changes inArkansas since 1963.

Results

Individual characters appeared to be randomly distributed throughout the state (Fig. 6).The distribution of the average number of tabulated Blanchards cricket frog characterspossessed by frogs in each county is found in Figure 6. These data were as follows: (1)nose warts, (2) pectoral fold, (3) foot webbing, (4) areola, (5) leg stripe. Countiespossessing individuals classifiable as A. c. blanchardi, A. c. crepitans, or subspeciesintergrades are shown in Figure 7.

When excluding the central range of the species (Arkansas-Mississippi-Missouri),DFA correctly classified 73.5% of the specimens. Animals from the southeast (Georgia-Florida) were correctly classified as A. c. crepitans in 66.3% of the cases, and specimensfrom the northwest (Nebraska-South Dakota) were correctly identified as A. c. blanchardiin 83.6% of the cases. Table 1 shows the group statistics, tests of equality of group means,and the classification results from the DFA.

When considering specimens from Arkansas-Mississippi-Missouri alone, discriminantfunction analysis correctly classified 31.8 % of the specimens. It correctly classified78.4% as A. c. crepitans, and 32.9% as A. c. blanchardi. Of those from the intergradezone, 8.4% were correctly classified. Intergrades were incorrectly identified as A. c.blanchardi in 23.3% of cases and 68.3% were incorrectly identified as A. c. crepitans.Table 2 shows the group statistics, tests of equality of group means, and the classificationresults from the DFA. The canonical discriminant functions are displayed in Figure 8.

When all specimens were considered, DFA correctly classified 47.1% of all thespecimens. A. c. crepitans was correctly assigned 18.0% of the time, whereas A. c.blanchardi was correctly assigned in 33.1% of cases. Specimens originating from theintergradation zone were correctly identified in 73.0% of the cases. Table 3 shows thegroup statistics, tests of equality of group means, and the classification results from theDFA. The canonical discriminant functions are displayed in Figure 9.

When Arkansas-Mississippi-Missouri specimens were considered as coming from asingle region without consideration of the proposed intergradation zone, these specimenswere correctly identified as originating from that region in 85.9% of cases. The animalscollected from Nebraska-South Dakota were correctly identified in 88.1% of the cases,and those from Georgia-Florida could be correctly identified in 54.7% of the cases.Georgia-Florida specimens were misplaced in Nebraska-South Dakota in 28.4% of thecases, but 16.8% were of these were misplaced in Arkansas. Only 13.4% of Nebraska-


1104ZOOTAXA South Dakota specimens were misplaced in Georgia-Florida. Table 4 shows the group

statistics, tests of equality of group means, and the classification results from the DFA.The canonical discriminant functions are displayed in Figure 10.

TABLE 1. Results of the discriminant function analysis (DFA) when comparing A. crepitans fromNebraska-South Dakota to Georgia-Florida. A. Group statistics, B. Tests of equality of groupmeans, C. Classification Results.

A. Group Statistics

B. Tests of Equality of Means

C. Classification Results (73.5% classified correctly)

Valid N (list-wise)RANGES Character Mean Standard Deviation Unweighted Weighted

South Dakota WART .2239 .4200 67 67.000

Nebraska WEBBING .5672 .4992 67 67.000

FOLD 7.463E-02 .2648 67 67.000

SPOTS .8060 .3984 67 67.000

NO STRIPE .8507 .3590 67 67.000

Georgia WART .3474 .4787 95 95.000

Florida WEBBING .6947 .4630 95 95.000

FOLD .1684 .3762 95 95.000

SPOTS .6632 .4751 95 95.000

NO STRIPE .4000 .4925 95 95.000

Total WART .2963 .4580 162 162.000

WEBBING .6420 .4809 162 162.000

FOLD .1296 .3369 162 162.000

SPOTS .7222 .4493 162 162.000

NO STRIPE .5864 .4940 162 162.000

Wilks' Lambda F df1 df2 P

WART .982 2.889 1 160 .091

WEBBING .983 2.796 1 160 .096

FOLD .981 3.084 1 160 .081

SPOTS .975 4.045 1 160 .046

NO STRIPE .797 40.796 1 160 .000

Predicted Group MembershipRANGES SD/NB GA/FL Total

Original Count SD/NB 56 11 67

GA/FL 32 63 95

Percent Correct SD/NB 83.6 16.4 100.0

GA/FL 33.7 66.3 100.0


1104ZOOTAXATABLE 2. Results of discriminant function analysis (DFA) when comparing A. crepitans from

Northwest Arkansas-Missouri, Southeast Arkansas-Mississippi, and the intergradation zone inArkansas. A. Group statistics, B. Tests of equality of group means, C. Classification Results.

B. Tests for Equality of Group Means

C. Classification Results (31.8% of cases correctly classified)

A. Group Statistics Valid N

Range Characters Mean Standard Deviation(list-wise)

Unweighted WeightedNorthwest WARTS .2479 .4324 359 359.000

WEBBING .1421 .3496 359 359.000

FOLD .3788 .4858 359 359.000

SPOTS 6.407E-02 .2452 359 359.000

NO STRIPE .1337 .3408 359 359.000

Southeast WARTS .1749 .3804 366 366.000

WEBBING .1694 .3756 366 366.000

FOLD .2377 .4263 366 366.000

SPOTS .1093 .3124 366 366.000

NO STRIPE .1257 .3319 366 366.000

Intergradation WARTS .1767 .3817 747 747.000

Zone WEBBING .1580 .3650 747 747.000

FOLD .3213 .4673 747 747.000

SPOTS 8.835E-02 .2840 747 747.000

NO STRIPE .1178 .3226 747 747.000

Total WARTS .1936 .3953 1472 1472.000

WEBBING .1569 .3639 1472 1472.000

FOLD .3145 .4645 1472 1472.000

SPOTS 8.764E-02 .2829 1472 1472.000

NO STRIPE .1236 .3293 1472 1472.000

Wilks' Lambda F df1 df 2 PWARTS .994 4.504 2 1469 .011

WEBBING .999 .517 2 1469 .596

FOLD .988 8.613 2 1469 .000

SPOTS .997 2.325 2 1469 .098

NO STRIPE 1.000 .292 2 1469 .747

Predicted Group MembershipRANGE Northwest Southeast Intergradation Total

Original Count Northwest 118 220 21 359

Southeast 60 287 19 366

Intergradation 174 510 63 747

Percent Correct Northwest 32.9 61.3 5.8 100.0

Southeast 16.4 78.4 5.2 100.0

Intergradation 23.3 68.3 8.4 100.0


1104ZOOTAXA TABLE 3. Results of discriminant function analysis (DFA) when comparing A. crepitans from the

entire northwest region, entire southeast region, and intergradation zone. A. Group statistics, B.Tests of equality of group means, C. Classification Results.

A. Group Statistics

B. Tests of Equality of Group Means

C. Classification Results (47.1% correctly classified). Predicted Group Membership.

Valid N (list-wise)

RANGE Mean Standard Deviation Unweighted Weighted

Northwest WARTS .2441 .4301 426 426.000WEBBING .2089 .4070 426 426.000

FOLD .3310 .4711 426 426.000SPOTS .1808 .3853 426 426.000

NO STRIPE .2465 .4315 426 426.000Southeast WARTS .2104 .4080 461 461.000

WEBBING .2777 .4483 461 461.000FOLD .2234 .4170 461 461.000

SPOTS .2234 .4170 461 461.000NO STRIPE .1822 .3864 461 461.000

Intergradation WARTS .1767 .3817 747 747.000WEBBING .1580 .3650 747 747.000

FOLD .3213 .4673 747 747.000SPOTS 8.835E-02 .2840 747 747.000

NO STRIPE .1178 .3226 747 747.000Total WARTS .2038 .4029 1634 1634.000

WEBBING .2050 .4038 1634 1634.000FOLD .2962 .4567 1634 1634.000

SPOTS .1506 .3577 1634 1634.000NO STRIPE .1695 .3753 1634 1634.000


WARTS .995 3.898 2 1631 .020WEBBING .985 12.728 2 1631 .000

FOLD .990 8.288 2 1631 .000SPOTS .973 22.979 2 1631 .000

NO STRIPE .980 16.622 2 1631 .000

RANGE Northwest Southeast Intergradation TotalOriginal Count Northwest 141 28 257 426

Southeast 89 83 289 461

Intergradation 154 48 545 747

Percent Correct Northwest 33.1 6.6 60.3 100.0

Southeast 19.3 18.0 62.7 100.0

Intergradation 20.6 6.4 73.0 100.0


1104ZOOTAXATABLE 4. Results of discriminant function analysis (DFA) when comparing A. crepitans from

Nebraska-South Dakota, Georgia-Florida, and Arkansas-Mississippi-Missouri as three distinctregions. A. Group statistics, B. Tests of equality of group means, C. Classification Results.

A. Group Statistics

B. Tests of Equality of Group Means

C. Classification Results (85.9% correctly classified). Predicted Group Membership.

StandardValid N

(list-wise)Ranges Characters Mean Deviation Unweighted Weighted

Arkansas WART .1936 .3953 1472 1472.000Mississippi WEBBING .1569 .3639 1472 1472.000Missouri FOLD .3145 .4645 1472 1472.000

SPOTS 8.764E-02 .2829 1472 1472.000NO STRIPE .1236 .3293 1472 1472.000

Nebraska WART .2239 .4200 67 67.000South Dakota WEBBING .5672 .4992 67 67.000

FOLD 7.463E-02 .2648 67 67.000SPOTS .8060 .3984 67 67.000

NO STRIPE .8507 .3590 67 67.000Georgia WART .3474 .4787 95 95.000Florida WEBBING .6947 .4630 95 95.000

FOLD .1684 .3762 95 95.000SPOTS .6632 .4751 95 95.000

NO STRIPE .4000 .4925 95 95.000Total WART .2038 .4029 1634 1634.000

WEBBING .2050 .4038 1634 1634.000FOLD .2962 .4567 1634 1634.000

SPOTS .1506 .3577 1634 1634.000NO STRIPE .1695 .3753 1634 1634.000


WART .992 6.629 2 1631 .001WEBBING .869 123.286 2 1631 .000

FOLD .984 12.977 2 1631 .000SPOTS .715 325.181 2 1631 .000

NO STRIPE .829 167.701 2 1631 .000

Ranges AR/MS/MO SD/NB GA/FL TotalOriginal Count AR/MS/MO 1297 68 107 1472

SD/NB 3 55 9 67GA/FL 16 27 52 95

Percent Correct AR/MS/MO 88.1 4.6 7.3 100.0SD/NB 4.5 82.1 13.4 100.0GA/FL 16.8 28.4 54.7 100.0


1104ZOOTAXA

FIGURE 8. Canonical discriminant function for subspecific characters from the Arkansas-Mississippi-Missouri portion of A. crepitans Range. Key: 0) Northwest, 1) Southeast, 2)Intergradation zone.

FIGURE 9. Canonical discriminant function for subspecific characters from the entire range of A.crepitans, including the intergradation zone. Key: 0) Northwest, 1) Southeast, 2) Intergradationzone


1104ZOOTAXAMales collected at Smallen Cave were slightly larger than that described by Harper

(0SVL = 24.2 mm, 0body mass = 1.69 g, n = 5), but within the range of those found in both

Nebraska-South Dakota and Georgia-Florida. Both the mean (1.29 g) and median (1.34 g)values in Nebraska-South Dakota adult male BMs were similar to the mean (1.3 g)reported by Harper (1947, 1.3g), whereas the mean (22.6 mm) and median (23.2 mm)SVLs in Nebraska-South Dakota were slightly less than his results (24.1 mm). Mean (1.18g) and median (1.16 g) adult BM values for Georgia males were smaller than thosereported by Harper. Mean (22.2 mm) and median (22.0 mm) SVLs were close to Harpers(1947) observations. There was no significant difference in SVL between males fromNebraska-South Dakota and those from Georgia-Florida (Mann Whitney: U = 2180.0, CI= -0.400, 2.000), although BM was significantly different (Mann Whitney: U = 2230.5, CI= 0.0099, 0.2900). In females, both SVL (Mann Whitney: U = 4448.5, CI = 2.599, 5.300)and BM (Mann Whitney: U = 4547.5, CI = 0.4500, 0.9799) were significantly larger inSouth Dakota-Nebraska than in Georgia-Florida. Snout-vent length in A. crepitans from

Arkansas remained consistent since 1963 for both males (r2 = 0.012, df = 207, p = 0.117)

and females (r2 = 0.007, df = 207, P = 0.218). Tibiotarsus length and body length were not

independent (r2 = 0.75, df = 374, P = 0.000). Table 5 contains the character distributionfor specimens collected at Smallens Cave, the origin of the holotype. There was no

change in SVL (r2 = 0.012, P = 0.117) or BM (r2 = 0.003, P = 0.218) since 1963.

FIGURE 10. Canonical discriminant function for subspecific characters from the entire range ofA. crepitans without the designated intergradation zone. Key: 0) Arkansas-Mississippi-Missouri,1) Nebraska-South Dakota, 2) Georgia-Florida.


1104ZOOTAXA TABLE 5. Character distribution in a sample of A. crepitans from Smallens Cave (Christian

County, Missouri). B = A. c. blanchardi character, C = A. c. crepitans character, SVL = snout-ventlength. Total = Number of total Blanchardian characters for that individual. Percent Blanchard =the percent of individuals possessing the Blanchards character. The Percent Blanchard Total cell isthe percent of the specimens with at least three Blanchards characters.

Discussion

Subspecies distribution in Arkansas appeared random when total numbers of charactersper specimen were considered (Fig. 6). This distribution appeared to violate the rules fordefining a subspecies because a subspecies is, by definition, a geographically defined race.Both subspecies morphotypes were observed in samples from throughout the state (Fig. 7).Acris c. blanchardi, A. c. crepitans, and integrades were frequently found within the samearea of a single pond or creek. This distribution suggested that these characters mightdefine either a cline or a series of varieties within a single species as defined by Mayr(1969). Previous molecular studies have shown a mixture of results. Some suggestdiscrete regions of differentiation on a large scale (Dessauer and Nevo 1969), minimalcorrelation between genetics and geography with local adaptation at a small scale(Gorman and Gaines 1987, Ward et al. 1987), and overall abiguity (Salthe and Nevo 1969)without evidence of subspecies differences. Previous studies have shown behavioralevidence of subspecies (Capranica et al. 1973, Nevo and Caparanica 1985, Ryan andWilcyznski 1988, Ryan et al. 1990, McClelland et al. 1998). These studies suggested thatdifferences might reflect divergence due to habitat use in different regions. It is possiblethat these differences might define different subspecies, but this needs further clarificationsince they were conducted based on the assumption that A. c. blanchardi was a validsubspecies. Such variation can be produced simply based on clines.

Performance of DFA on the Arkansas-Missouri-Mississippi portion of the sample didnot provide convincing evidence that the subspecies were different (Fig 8, Table 2).Although 78.4% of specimens from the southeast were correctly classified, 61.3% ofspecimens from the northwest and 68.3% of specimens from the intergradation zone wereplaced in that region as well. 32.9% of the specimens were correctly placed in thenorthwest. This information suggests that this region is dominated by A. c. crepitans, and

Specimen Number Sex SVL (mm) Mass (g) Stripe Web Fold Warts Areola Total

ASUMZ 27117 M 24.5 1.77 B C B B C 3-B ASUMZ 27119 M 25.0 1.83 C C B B C 2-BASUMZ 27120 M 24.0 1.53 C C B C C 1-BASUMZ 27121 M 24.5 1.77 C C B C C 1-BASUMZ 27122 M 23.0 1.53 C B B B C 3-BASUMZ 27123 F 28.5 3.09 B B B C B 4-B Percent Blanchard -- 0 = 24.2 0 = 1.69 33% 33% 100% 50% 16.5% 50%


1104ZOOTAXAthat A. c. blanchardi is rare or absent here. None of the Blanchardian characters was

prevalent in this region. The most common Blanchardian character was the pectoral foldthat was found in 31.5% of the animals from throughout the region. Areola were mostcommon in the southeast part of this region (10.9%), but were only present in 8.8% ofspecimens from the entire region accounting for the rarest Blanchardian character in thisanalysis. The low percentage of specimens correctly classified (31.8%) provides littleevidence that multiple subspecies are present in Arkansas-Mississippi-Missouri and thatthe intergrade zone is probably located north of its current placement.

When specimens from Nebraska-South Dakota and Georgia-Florida were included inthis analysis, the data become more confusing (Table 3, Fig 9). Although 73% of thespecimens from the proposed intergradation zone were classified as intergradations, 60.3%of A. c. blanchardi and 62.7% of A. c. crepitans were misclassified as intergradations.Nearly equal proportions of southeast animals (19.3%) and intergradations (20.6%) weremisclassified as A. c. blanchardi. Specimens from the southeast were misclassified as A.c. blanchardi (19.3%) more often than they were “correctly” classified as A. c. crepitans(18.0%). These results seem to suggest that the intergrade zone is positioned correctly butonly 47.1% of cases could be correctly classified in this analysis, suggesting lowconfidence in the characters for discerning these subspecies.

Specimens from Nebraska-South Dakota originate from the extreme northwest portionof the geographic range of A. crepitans, and the specimens from Georgia-Florida representthe extreme southeast portion of the species geographic range. Because previous wisdomaccepted that northwest specimens were A. c. blanchardi and that southeast specimenswere A. c. crepitans, frogs from these two regions should be maximally different comparedto frogs from the remainder of this species range. This was not observed. The specimensfrom Nebraska-South Dakota were correctly classified in 83.6% of cases; however, 66.3%of the specimens from Georgia-Florida were correctly classified. Only 22.4% ofNebraska-South Dakota specimens possessed snout warts, whereas 34.7% of Georgia-Florida specimens had this trait. Among the other Blanchard traits, webbing (69.5% vs.56.7%) and the pectoral fold (16.8% vs. 7.5%) were more common in Georgia-Floridaspecimens than in Nebraska-South Dakota specimens. Areola were equally common inboth regions. Areola, thigh striping, pectoral folds, and foot webbing were expected to becommon in Nebraska-South Dakota, but rare in Georgia-Florida. The most dramaticcharacter difference between these two regions was the thigh striping. Thigh striping waspresent in 80% of Nebraska-South Dakota specimens but only 40% of Georgia-Floridaspecimens. This supports Harpers contention that this is the most defining character of A.c. blanchardi, although conflicting distributions among the other characters seem tocontradict his descriptions.

If each region is compared without regard for an intergrade zone, specimens are fairlyaccurately placed in their respective regions (Table 4). Georgia-Florida specimens weremisclassified as originating from Nebraska-South Dakota in 28.4% of cases and


1104ZOOTAXA misclassified as originating from the central region 16.8% of the time. Arkansas-

Mississippi-Missouri and Nebraska-South Dakota specimens appear to be the most readilydiscernable as they are both misplaced in the others respective category in less than 5% ofcases. Arkansas-Mississippi-Missouri and Georgia-Florida specimens are not as different.It appears that a large portion of southeastern specimens is similar to those from the centralregion, although few (7.3%) of central specimens were misclassified as coming from thesoutheast United States. These results suggest that the intergrade zone may need to bemoved north.

Smallens Cave was the source of Harpers holotype; yet only 17% (1/6) specimenscollected there had greater than three Blanchardian characters (i.e. four characters).Among the remaining five specimens, three had only one or two characters. The bodydimensions of specimens from this location were similar to those reported by Harper(1947). This parameter is confusing across the range of A. crepitans. Harper stated that A.c. blanchardi is 2.5 times the SVL of its counterpart. This was not observed. Male SVLdid not vary, as there were no statistical differences identified among these regions. Bodymass was statistically larger in the northwest, but the difference was not as dramatic assuggested by Harper (1947). Northwestern female SVL and BM were both larger in thenorthwest. These differences in females were not as large as suggested by Harper. Datacollected by Nevo (1973) and Neill (1950) also suggest body mass and SVL are muchsmaller in the range of A. c. blanchardi than originally proposed by Harper (1947).

These results suggest that the characters described by Harper (1947) are of no usewhen discerning A. c. crepitans from A. c. blanchardi. These characters are difficult todefine, identify, and use. The specimens from Nebraska-South Dakota are onlymoderately discernable from those in Georgia-Florida. When the central region isconsidered alone, A. c. crepitans is the dominant form. When the extreme northwest andsoutheast portions of the range are included, most animals are statistically classified asintergrades. Finally, when taken as three broad distinct regions specimens are usuallyclassified correctly. This provides little evidence of a clear-cut intergrade zone the variousDFAs suggest it was correctly placed or positioned to far north or south depending on thestructure of the analysis. These differences between the various DFAs suggest this speciesrange is a complex of clines and are of minor taxonomic significance. In order for thesecharacters to be useful for identification of a subspecies, they must have a definitegeographic basis.

There appears to be a gradual increase in the prevalence of Blanchardian charactersfrom the southeast to the northwest extent of the range. This may be best described asclinal and not subspecific variation. When discerning subspecies, there should be alimited intergradation zone, beyond which the groups are easily distinguishable (Mayr1969). Only 50% of the animals collected at Smallens Cave had more than half of theBlanchardian characters, and 33% (1/3) possessed one or fewer of these characters. Thisplaces substantial doubt on the validity of this subspecies.


1104ZOOTAXAMany of the diagnostic characters were poorly described by Harper (1947). His

statement “leg stripe not bordered by a light area” is difficult to discern. The exactmeaning of “warts on the snout” was questionable. The presence of areola on the venterand the presence of a pectoral fold were fairly easy to distinguish; however, this charactermight reflect age and not subspecific affinity (McCallum 2003, Burkett 1984).

The extent of webbing on the hind foot was sometimes confusing because some frogspossessed one foot with extensive webbing, and the other with webbing not reaching thedistal joint. Some feet actually had webbing on one side of the toe that would identify it asA. c. blanchardi while the adjacent webbing designated this specimen as A. c. crepitans.Variation in this character might be better explained by Nevos (1973) suggestion that it is aresponse to potential predator presence and not a subspecific diagnostic character.

The seemingly random pattern of subspecific characters in Arkansas and southwestMissouri points to two questions.

1) Has A. c. crepitans displaced A. c. blanchardi, and what does this mean in regard to A.c. blanchardi declines elsewhere?

There is no current evidence of a northward advancement of A. c. crepitans charactersinto northwest Arkansas. Trends analysis of the SVL and BM (proposed as the mostdramatic differences between these subspecies with A. c. blanchardi being at least twice aslarge as A.c. crepitans) suggest this character has remained constant throughout theexistence of the ASUMZ herpetological collection. If there were a northward advance, theSVL should have decreased over time, but the evidence suggests that if any northwardadvancement did occur, it happened prior 1963.

2) Where does the intergradation zone of these subspecies occur? No intergradation zone appears to exist between these subspecies. A. c. blanchardi

may not be a valid subspecies. The type specimen is from Christian County, Missouri butthe measurements used to describe this subspecies were taken from five adult males and10 adult females from Tulsa County, Oklahoma. Instead of documenting the number ofadditional specimens examined and from what collections, Harper (1947) stated, “thenumber (not given) of specimens was so extensive that specimen numbers were notincluded to save space”. It is possible that, by chance Harper measured a small sample ofthe largest frogs in the population. Further problems with the systematics of this genus areevident considering Moores (1997) findings regarding variation in the cytochrome-b genein Hylidae. Moore found that this gene easily separated all other genera in Hylidae exceptAcris. Furthermore, subspecific differences were not detected using this gene.

There has been much confusion identifying these subspecies. Regarding animals wellwithin the range of A. c. crepitans, Mount (1975) states, “A. crepitans from southernAlabama more closely resemble A. c. blanchardi than A. c. crepitans”. Regan (1972)


1104ZOOTAXA anecdotally suggested that A. c. blanchardi might not be a valid subspecies. Many of the

diagnostic characters used to define the subspecies are of questionable utility or difficult tointerpret. Our results when combined with previous studies provide strong evidence thateither the two subspecies (A. c. blanchardi and A. c. crepitans) are equivalents withcomplex clinal patterns for these designated characters, or A. crepitans is a complex ofmultiple closely related species requiring molecular techniques to distinguish. Because wefind the morphometrics used to define A. c. blanchardi of doubtful utility, it isrecommended that use of this subspecies name be suppressed until future studies deemotherwise and that IUCN conservation designations for this species be reevaluatedaccordingly. All members of this subspecies should be more appropriately designated asA. c. crepitans. Should further investigations find A. c. blanchardi to be completelyinvalid it would be a paradox, for it was Frank Blanchard who was known for histaxonomic conservatism (Gloyd 1940).

Acknowledgments

We wish to thank B. Wheeler, J. Collins, E. Moriarty, J. McCallum, R. Buchanan, J. Farris,A. Grippo, R. Abernathy, C. McAllister, and all others that provided insight and discussionon matters related to this study (particularly the excellent feedback I received from theanonymous reviewers).

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zootaxa, acris (anura, hylidae)

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