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Gayana (Concepción)

versión On-line ISSN 0717-6538

Gayana (Concepc.) v.74 n.1 Concepción  2010

http://dx.doi.org/10.4067/S0717-65382010000100006 

Gayana 74(1): 23-36, 2010 ISSN 0717-652X

 

AMBIENTE TERRESTRE

 

A multivariate analysis of taxonomic limits in Diplolaemus Bell 1843

 

Un análisis multivariado de los límites taxonómicos en Diplolaemus Bell 1834

 

Pedro F. Victoriano1'2'*, Tanía M. Coronado1 & Juan Carlos Ortiz1'2

1 Departamento de Zoología. Facultad de Ciencias Naturales y Oceanográfcas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.

2 Centro de Investigaciones en Ecosistemas Patagónicos. Coihaique, Chile. * E-mail: pvictori@udec.cl


ABSTRACT

The gemís Diplolaemus Bell, 1843 is a common squamate component of the Patagonian región of South América. Considerable taxonomic confusión exists within this gemís, particularly about the status of Chilean-Andean populations and the actual distribution of D. leopardinas (Werner, 1898). In an attempt to clarify the taxonomic status and distribution of Diplolaemus species, we performed a principal component analysis (PCA) and discriminant function analysis (DFA) using both standard morphometric and meristic data. Multivariate summaries of morphometric data show that most species are poorly discriminated, with the exception of D. darwinii. In contrast, a PCA analyses performed on the meristic data clearly distinguish three discrete groups: 1. D. darwinii, 2. D. sexcinctus including the Chilean populations, and 3. populations from Mendoza, Argentina, including the holotype of D. leopardinus and of D. bibronii. A DFA consistently assigned with a high percentage of successful classifcation (95%) individuals of the species D. darwinii, D. sexcinctus, and D. bibronii. The group with lowest successful rate in the cross validation procedure (78%) was D. leopardinus (including populations from Mendoza), with misidentifcations assigned only to D. bibronii. The group formed by Mendoza populations and the holotype of D. leopardinus is visibly distinct from remaining D. bibronii in colour patterns. The holotype of D. leopardinus is clearly differentiated from the Chilean-Andean populations. Our results support the assignment of populations from Mendoza to D. leopardinus, and suggest that the Chilean-Andean populations currently assigned to this taxon should be referred as D. sexcinctus, together with populations from the Argentinean provinces of Río Negro and Neuquén.

Keywords: Species limits, taxonomy, Patagonia, Polychrotidae.


RESUMEN

El género Diplolaemus Bell, 1843 es un lagarto típico de la región patagónica de Sudamérica. Aún existe considerable confusión taxonómica dentro de este género, especialmente en torno al estatus de las poblaciones andino-chilenas y de la distribución actual de D. leopardinus (Werner, 1898). En un intento de aclarar la situación taxonómica y distribución de las especies del género, realizamos análisis de componentes principales (PCA) y de funciones discriminantes (AFD), usando tanto variables morfométricas como merísticas. En síntesis, los datos morfométricos indican que el género es altamente conservado morfológicamente por lo que la mayor parte de las especies son pobremente discriminadas, con la excepción de D. darwinii. En contraste, el PCA realizado con datos merísticos claramente distingue tres grupos: 1. D. darwinii, 2. D. sexcinctus incluyendo las poblaciones chilenas de Alto Biobío, y 3. Poblaciones mendocinas incluyendo al holotipo de D. leopardinus más D. bibronii. El análisis de AFD asignó consistentemente y con un alto porcentaje de éxito en la clasifcación (95%), individuos de las especies D. darwinii, D. sexcinctus y D. bibronii. El grupo con la menor tasa de éxito en la validación cruzada (78%) fue D. leopardinus (incluyendo las poblaciones mendocinas), donde todas las asignaciones erradas fueron a D. bibronii. El grupo de las poblaciones mendocinas más el holotipo de D. leopardinus son claramente distintos de D. bibronii en cuanto al patrón de coloración. El holotipo de D. leopardinus es claramente distinguido de las poblaciones chilenas de Alto Biobío. Estas últimas son poblaciones andinas asignables a D. sexcinctus. Nuestros resultados soportan la asignación de las poblaciones mendocinas a la especie D. leopardinus, y sugieren que las especies andinas de Alto Biobío en Chile, previamente tratadas con este nombre específico, debieran ser asignadas a D. sexcinctus, junto a las poblaciones de Río Negro y Neuquén de Argentina.

Palabras clave: Límites de especies, taxonomía, Patagonia, Polychrotidae.


 

INTRODUCTION

Lizards of the genus Diplolaemus (Leiosauridae) distribute across the Patagonian Province in Chile and Argentina, and extend north and northwest along the edge of the Andes and into valleys characterizedby the typical physiognomy of this biogeographical formation (Cei 1971, Cei 1979). The genus was described by Bell (1843) in the Charles Darwin volume which report the material collected during the expedition of the H.M.S. Beagle. Atthattime, two species, D. darwinii and D. bibronii, were described from Puerto Deseado, Santa Cruz Province, Argentina (Fig. 1). These species are sympatric across a wide geographic range that includes southern Argentina and adjacent Chile (Fig. 2, Cei 1986, Avila et al. 2001, Ibargüengoytia & Schulte 2001).

In his taxonomic treatment, Boulenger (1885), without justifcation, synonymized D. bibronii with D. darwinii. Later workers resurrected D. bibronii based on clear differences in scalation and color pattern (Anderson 1898, Stejneger 1909, Donoso-Barros & Codoceo 1962, Peters & Donoso-Barros 1970). The diagnostic features identifed by these authors are clearly valid for Diplolaemus populations in southern Argentina and Chile. However, in northern áreas extensive phenotypic variation prevenís the unambiguous assignment of some populations either to D. darwinii or to D. bibronii populations (Cei 1986, Cei et al. 2003). Stejneger (1909) reported on this extensive phenotypic variation in some populations, at the time that discussed the possible occurrence of a new species in the northern range, based on an individual whose characteristics were intermediate betweenD. darwinii anáD. bibronii.

Werner (1898) described D. leopardinus (Fig. 3 and Fig. 4), based on individuáis from the collection Píate, which was made from 1893 up 1895, and designated Santiago (Chile) as the type locality. No additional specimens have ever been found in the vicinity of the type locality. Donoso-Barros (1965; 1974) collected several individuáis of Diplolaemus from Laguna del Laja National Park in the Central Chilean Andes, which he identifed as D. leopardinus. He also indicated that its distribution did not reach the type locality (Santiago of Chile) indicated by Werner (1898). Cei (1986) recognized two undescribed Argentinean forms which he referred to as the "forma alto patagónica" (high Patagonian form), and "forma mendocina" (Mendoza form). Cefs high Patagonian form occurs in the Andes and sub-Andean volcanic regions of Patagonia, from approximately 37°S up 4S, while the Mendoza form occurs in Mendoza Province, Argentina, but neither was formally described.

Due to this taxonomic confusión, we have reconsidered the status of D. leopardinus and the two forms of Cei (1986). Recently, Cei et al. (2003) described the new species D. sexcinctus onthe basis of the "alto patagónica" populations; its holotype is from Río Negro, Argentina, and these authors included within this species the populations from Mendoza. These authors maintain the original interpretation that D. leopardinus is distributed in Chile, in Laguna del Laja (referring to Donoso Barros 1966), and its unresolved relationship with D. sexcinctus require further research. The objective of this work is to summarize the meristic and morphometric variation among all recognized species of Diplolaemus, with an emphasis in the Andean-Chilean populations and the distribution of D. leopardinus.

MATERIALS AND METHODS

We have analyzed 125 individuáis of all the recognized species of Diplolaemus. Details about the number of individuáis for each species are shown in Table 1. Details about localities from where lizards were collected are included in Appendix 1. Some of the lizards used in this study were obtained from the northwest slope of Antuco Volcano in Chile (37° 2LS - 71° 19'0), during feldtrips to the Laguna del Laja National Park (Región del Biobío, Chile), in the late spring and summer of 2000. Procedures of transport, caging, care and euthanasia were according to Greene (1995). Voucher specimens were deposited in the Museo de Zoología de la Universidad de Concepción (MZUC). Individuáis described by Cei et al. (2003; D. sexcinctus) were borrowed from the Sociedad Naturalista Andino Patagónica of San Carlos de Bariloche, Argentina (MIC), or the Instituto de Biología Animal, Universidad Nacional de Cuyo, Argentina (IBA). The type series of D. darwinii Bell, 1843 and D. bibronii Bell, 1843, were borrowed from the British Museum Natural History, England (BMNH), and other samples were obtained from Museo Regional de Concepción, Chile (MCR), the Museo Nacional de Historia Natural de Montevideo, Uruguay (MNHM), and the Museo Nacional de Historia Natural de Santiago, Chile (MNHN). The holotype of D. leopardinus (Werner, 1898) was borrowed from the Zoologischen Museum Berlín, Germany (ZMB). Locality and other data of the specimens examined are presented in Appendix 1.

Following the methods of Lamborot & Díaz (1987), morphometric measures were obtained to the nearest 0.1 mm using a digital caliper. The nomenclature of the meristic (scalation) characters was based principally on Donoso-Barros (1966) and Cei (1986). To indícate the shape, number, and relative location of the holotype’s cephalic scales, outlines were drawn using a stereozoom microscope. The abbreviations used for the meristic and morphometric characters were: SPL (supralabial scales, counted on one side), INF (infralabial scales, counted on one side ), SNR (scales between nasal and rostral scale), SSoSp (scales between suboculars and supralabials), SNG (scales between snout and guiar fold), PSF (postfacial scales, counted on both sides), INPM (scales between infralabial and postmental), SEE (scales between eye and ear-opening), PMS (postmental scales, counted on one side), SAB (scales around midbody), SMDL (scales along middorsal line), SMDH (scales along the middorsal line on the head, counted from the rostral one to the neck), SVL (snout-vent length), TL (tail length), MAX (máximum head width), HL (head length, measured from snout to the ear opening), DEO (distance from ear opening to eye), DEN (eye-nostril distance), DPOEF (distance from posterior border of eye to facial), DIS (distance from interparietal to snout), and SGF (distance from snout to guiar fold).

The data were analyzed using STATISTICA V. 5.1., after a log transformation directed to eliminate the heterogeneity of variances. We have included exclusively adult individuáis in the multivariate analysis inorderto exelude some ontogenetic effect onthe results. We applied a diagnostic testfor normality and heterogeneity of variance (with log transformed data), and then used nine morphometric and 12 meristic characters in an exploratory analysis (Principal component analysis, PCA), to determine what combinations of characters (if any) delimited groups concordant with the previously described species, and to determine what differences discriminated among the species included in this work. Subsequently, an analysis of mean differences was performed between species for the meristic characters with a MANOVA. After these analyses, apost-hoc Tukey’s test was conducted to compare species, and for each one of the scalation characters. To test the reliability of the meristic data to correctly assign individuáis to each of the respective species, a discriminant function analysis was conducted, and when the functions were determined, a cross validation procedure was applied to test the reliability of each function.

RESULTS

Variation and comparative analysis. Table 1 presents the sample size by species including both adults and subadults individuáis, the mean, standard deviation, and range of the morphometric and meristic characters of the four studied species of Diplolaemus. In general, the greatest differences between species were detected in the meristic characters, particularly those of the head. Due to the extensive overlap of the morphometric characters, these were not useful for discriminating between species. However, clear differences exist for a large number of meristic characters that unambiguously discrimínate D. darwinii from the other species. D. darwinii does not overlap with any other species, including D. sexcinctus, for the character SPL, while PMS differentiate it from D. bibronii and D. leopardinus. In addition, D. darwinii does not overlap with D. leopardinus in INF, SNR, SNG, and INPM. Even though D. sexcinctus is not easily differentiated because it usually overlap in meristic characters with all other species, it does show important differences in two characters (INPM and PMS) relative to D. leopardinus and D. bibronii. For posterior analysis we used only adult individuáis; D. sexcinctus = 42, D. bibronii = 40, D. leopardinus = 9 and D. darwinii = 1.

Table 1. Sample size for each species, mean + standard deviation of the morphometric (measurements in millimeters) and meristic (scalation) characters for species oí Diplolaemus; ranges in parentheses. See text for variable abbreviations.

Tabla 1. Número de individuos por especie, promedio y desviación estándar de los caracteres morfométricos (medidos en milímetros) y merísticos para especies del género Diplolaemus; rangos en paréntesis. Ver el texto para las abreviaciones de las variables.

Due to the fact that the morphometric characters based Principal Component Analysis (PC A) did not resolve discrete groups for any of the Diplolaemus species, these were not used in the subsequent analyzes (Fig. 5). In this analysis Factor 1 (Eigenvalue = 3.285), explained 54.8% of the total variation and Factor 1 and 2 explained together 71.3%. (Eigenvalue = 0.991). Although the total variance explained by this analysis was high, the distribution of individuáis valúes inthe two factors did not conform discrete groups. The PCA based on meristic characters identifed three discrete groups. Factor 1 explained 39.14% of the total variation, and Factor 1 (Eigenvalue = 4.696) and Factor 2 (Eigenvalue = 1.696) explained together 53.27% of the total variation. In this axis, the variables with highest factor loading were SSoSp (factor loading = - 0.8091), SNG (factor loading = - 0.760), INPM (factor loading = - 0.736), and SEE (factor loading = - 0.739). The variables for the second factor with the highest factor loading were PMS (factor loading = 0.637) and SPL (factor loading = - 0.551). The scatterplot of the frst two components permitted separation of D. darwinii fxovaD. sexcinctus + D. leopardinus + D. bibronii (Fig. 6). Factor 2 separated the individuáis of D. sexcinctus from those of the other three species. D. leopardinus and D. bibronii overlap along both axes. Therefore, there is a greater difference at the scalation level for D. darwinii, with respect to the other species. On the other hand, D. leopardinus and D. bibronii are very similar.

To test the signifcance of the differences between species in meristic variables, a multivariate analysis of the variance for the total set of individuáis was conducted. Differences were highly signifcant (Lambda of Wilks = 0.0082; F(36.245) = 27.876; p < 0.001). The univariate tests of Tukey (Table 2) provide a greater number of signifcant differences for the comparisons involving D. darwinii, what is in agreement with the clear separation of this species in the PCA. On the other hand, when D. leopardinus is compared with D. bibronii, species that were indistinguishable in the PCA, signifcant differences were only found for the SPL and SMDLvariables. The comparisonD. bibronii - D. sexcinctus provided signifcant differences for seven variables (SPL, SSoSp, SNG, INPM, SEE, PMS andPSF), while the species D. sexcinctus provided signifcant differences with respect to D. leopardinus in 6 characters (SSoSp, SNG, INPM, PMS, SAB, and SMDL).

The discriminant function and its effcacy in assigning the individuáis of each one of the species of Diplolaemus is summarized in Table 3 and Table 4 respectively. Three discriminant canonic functions were generated (Table 3), each one with eight variables of scalation, which provided a high discrimination power. The classifcation matrix (Table 4) indicates that a highpercentage of the individual assignments were correct (96% of the total). The valúes are high for the species D. sexcinctus (96.5%), D. bibronii (97.9%), and D. darwinii (100%). However, the discriminant functions were not as successful for individual assignment of the individuáis of D. leopardinus; only 83.4% of these were correctly assigned, while the remaining 15.6% of the individuáis were all wrongly assigned to the species D. bibronii.

Table 2. Results of Tukey post-hoc test of log10 transformed meristic characters for all species oí Diplolaemus. (1) D. sexcinctus; (2) D. bibronii; (3) D. leopardinus; (4) D. darwinii. Valúes in the table are pairwise comparison probabilities. See text for variable abbreviations.

Tabla 2. Resultados del test post-hoc de Tukey de los caracteres merísticos transformados a los, para todas las especies de Diplolaemus.

Table 3. Results of discriminant function analyses of meristic variation in all species of the genus Diplolaemus. See text for variable abbreviations.

Tabla 3. Resultados de los análisis de función discriminante de la variación merística de todas las especies del género Diplolaemus. Ver texto para la abreviación de las variables.

table 4. Classification matrix obtained from the discriminant functions shown in Table 3.

tabla 4. Matriz de clasificación obtenida de las funciones discriminantes mostradas en la Tabla 3.

With respect to the coloration, the dorsal design clearly distinguishes the four species of the genus (Fig. 4). Even though D. sexcinctus can present variations in tonality, the design that is superimposed in the background is constant. The dorsal color pattern of D. sexcinctus consists in six transverse bands extending from the shoulder to the pelvic región (Fig. 2B-C, Fig. 3D; Ceiet al. 2003). Eachhalf of a single band forms a "butterfy wing" shape, and at the posterior margin of each "wing" there is a light blue spot. The body’s background color is gray-ochre, and the head is covered with dark brown spots. In the mouth, there are brown dots. There is a clear difference in color patterns between D. sexcinctus and D. leopardinus; in the latter the background is yellowish with small brown spots without the typical butterfy design present in D. sexcinctus. In D. darwinii the dorsal pattern is very irregular and characterized by a dendritic dark brown design over a gray-ochre background (Fig. 4). Finally, in D. bibronii the matrix color is grey-orange overlaid by symmetric brownish bands, and each band is bordered by a yellowish semicircle.

Figure 1. Original plates fromBell (1843), showing the species oí Diplolaemus described form the expedition of Charles Darwin. (A)D. darwinii, (B)D. bibronii.

Figura 1. Láminas originales del capítulo de Bell (1843), mostrando las especies de Diplolaemus descritas en la expedición de Charles Darwin. (A)D. darwinii, (B)D. bibronii

Figure 2. Map showing the recording localities of four species of Diplolaemus (modifed from Cei 1986). Patagonian boundaries (dashed lines), based on Cei (1979).

Figura 2. Sitios de registro para las especies de Diplolaemus (modifcado de Cei 1986). Límites de Patagonia (línea segmentada), basados en Cei (1979).

Figure 3. Dorsal view of (A) holotype of D. leopardinas (ZMB-13395), (B) adult male (MZUC-23303), and (C) adult female (MZUC-23302) oí Diplolaemus sexcinctus (Chilean populations).

Figura 3. Vista dorsal (A) del holotipo de D. leopardinus (ZMB-13395), (B) de macho adulto (MZUC-23303) y (C) de hembra adulta (MZUC-23302) de D. sexcinctus (poblaciones chilenas).

DlSTRIBUTION OF THE SPECIES (Fig. 2). Diplolaemus sexcinctus is known from the Argentinean provinces of Neuquén, Chubut, and Río Negro, and in the Patagonian extensions across the Andes into neighboring valleys in the upper part of the Chilean Biobío River basin. Following our proposed taxonomic status, D. leopardinus is restricted to the Argentinian Province of Mendoza. Diplolaemus bibronii is widely distributed across Patagonian landscapes in the Argentinian provinces of Chubut and Santa Cruz, and southeastern Chile. Finally, D. darwinii is the southernmost species of the genus, being known from the provinces of Chubut and Santa Cruz, Argentina, and from the Province of Magallanes in Chile (Fig. 2).

Figure 4. Comparisons of the dorsal pattern of four species of Diplolaemus. (A) D. darwinü (BMNH-0064), (B) D. bibronü (MZUC-23328), (C)D. leopardinas (ZMB-13395), and (D)D. sexcinctus (MZUC-23303).

Figura 4. Comparación de los patrones dorsales de cuatro especies de Diplolaemus. (A) D. darwinü (BMNH-0064), (B) D. bibronü (MZUC-23328), (C)D. leopardinus (ZMB-13395), y (D)D. sexcinctus (MZUC-23303).

Figure 5. Scatter diagram of the first and second principal component scores generated by principal component analy sis of morphometric characters in the species oí Diplolaemus. Gray triangles, D. sexcinctus; white squares, D. bibronü; black circles, D. leopardinus; black squares, D. darwinü.

Figura 5. Diagrama de dispersión de los valores del primer y segundo componente principal generado por análisis de componentes principales de los caracteres de variables morfométricas en las especies de Diplolaemus. Triángulos grises, D. sexcinctus; cuadrados blancos, D. bibronü; círculos negros, D. leopardinus; cuadrados negros, D. darwinü.

Figure 6. Scatter diagram of the frst and second principal component scores generated by principal component analysis of scalation characters in the species oíDiplolaemus. Gray triangles, D. sexcinctus; white squares, D. bibronii; black circles, D. leopardinus; black squares, D. darwinii.

Figura 6. Diagrama de dispersión de los valores del primer y segundo componente principal generado por análisis de componentes principales de los caracteres de escamación en las especies de Diplolaemus. Triángulos grises, D. sexcinctus; cuadrados blancos, D. bibronii; círculos negros, D. leopardinus; cuadrados negros, D. darwinii.

DISCUSSION

Multivariate comparisons in the PCA show that there is a high degree of phenotypic similarity among species of the gemís Diplolaemus. Withinthe contéxtof this high similarity, Diplolaemus darwinii is the most distinct phenetically, both in color pattern as well as in meristic characters. This higher distinction of D. darwinii was reported previously by Cei (1975) based on serological characters. In contrast to this observation, the other three species show modérate to extensive overlap in the magnitude of the morphometric variables analyzed, which makes their discrimination diffcult and has generated most of the taxonomic confusión The conservative morphology shownby some lizard species has been explained because of phylogenetic restriction or strong selection pressures (Malhotra & Thorpe 1994; Pianka & Vitt 2003; Losos 2009); any of these this could be the mechanism driving the similar morphology among Diplolaemus species.

An additional source of taxonomic confusión is the lack of information on the geographic provenience of the holotype of D. leopardinus, which is necessary to delimit the real geographical distribution of this taxon. However, it is importará to highlight the itinerary of the expedition that have originated the Píate collections, during which the holotype was obtained and which did not include localities cióse to the geographic distribution of Chilean D. leopardinus populations from the Andes sensu Donoso-Barros (1965), which are assigned to D. sexcinctus after this study. Cei et al. (2003) described D. sexcinctus based on the "alto patagónica" populations; its holotype is from Río Negro, Argentina. The authors included within this species the populations from Mendoza, and citing Donoso Barros (1966) maintained the original interpretation that D. leopardinus distributes in Laguna del Laja, Chile. Cei et al. (2003) wrote "The third species of the genus, Diplolaemus leopardinus Werner, is a Chilean lizard, scarcely and poorly cited for its still uncertain áreas in Neuquén. Recently, preliminary commentaries point out its possible relationships with the Argentinean six-banded populations, evidently sympatric in such a bordering zone. Thus, we are dealing with not yet solved taxonomic and nomenclatural problems, wanting Chilean cooperation, but impossible to be developed in our present research on Argentinean taxa". While, Ceiet al. (2003) in their Figure 1 assigned populations from Mendoza to D. sexcinctus, we here conclude that samples should be assigned to D. leopardinus. Meanwhile, Pincheira-Donoso et al. (2007), in an arricie on Liolaemus species, misunderstood the taxonomic discussion of Cei et al. (2003) and wrongly wrote "...the populations identifed as Diplolaemus leopardinus.. .by Donoso-Barros (1974) at Laguna del Laja (Chile), were recently described as the new species Diplolaemus sexcinctus (Cei /et al/. 2003)".

After Cei et al. (2003), ours is the first taxonomic study focusing in Diplolaemus that includes individuáis from Laguna del Laja, Chile. Then, this is to be considered the first assignment to D. sexcinctus of populations previously considered to belong to D. leopardinas.

On the other hand, it is possible that D. leopardinas inhabits the área near the Argentinean-Chilean border at the latitude of Santiago, where Cei (1986) recognizes the "Sudmendocinan form". Indeed, when comparing the dorsal design of the holotype of D. leopardinas, lizards from Mendoza, and Píate 4 of Cei (1986), and considering the results of the discriminant analysis, which included the holotype of D. leopardinas, it is reasonable to propose thatí). leopardinas inhabits the Mendoza región of Argentina. The principal difference between this species and D. sexcinctus is the number of post-mental scales and the dorsal color pattern. Thus, the three taxa source of taxonomic confusión, D. bibronii, D. leopardinus, and D. sexcinctus, can all be clearly discriminated from each other on the basis of color pattern in combination with post-mental scale counts.

Diplolaemus sexcinctus is often found in open shrubby and herbaceous habitats; however, this species also occurs in forests of Araucaria araucana (Cei 1970). This fact highlights the concordance of the distribution of this species with that of a forest that in the past (early Cenozoic), showed a wider distribution, including for example, the large Altiplanicie Central in Patagonia (Cei 1979). It is probable that D. sexcinctus originated as a species linked to this type of forest, and later colonized more exposed micro-habitats of volcanic origin, such as the slopes of the Antuco Volcano in the Chilean Laguna del Laja National Park. Some of the assigned populations of this species are found in volcanic áreas farther north, near the Nevados de Chillán, located outside the range of Araucaria araucana. This proposition may be rigorously tested by a detailed phylogeographic study of D. sexcinctus.

Cei (1979) proposed a zoogeographical subdivisión of Patagonia into two regions based on its herpetofauna. Diplolaemus has a current distribution that is almost completely concordant with the geographical extensión of the Patagonianprovince. However, of the four species of this genus, only D. sexcinctus and D. leopardinus are exclusive to the hypothesized ancient (southern) Patagonian región. D. bibronii is distributed predominantly in the southern Patagonian región, but the northern limit of its distribution extends to mid-latitudes of Patagonia (Cei 1986). The only species exclusive to Austral Patagonia is D. darwinii, and according to Cei (1979), this región corresponds to a distinct biogeographical unit as indicated by its herpetofauna. D. darwinii presents keeled caudal scales that according to Etheridge & Williams (1985) it is a plesiomorphic condition in the genus. Considering the species geographical distributions, it is reasonable to hypothesize thatí). darwinii or its ancestor must have separated early in the history of the genus, and that this speciation event could have occurred in the southern región of Patagonia. The origin of the remaining Diplolaemus species may have been associated with a northward advance of the clade, associated with periodic isolation and expansión events as a consequence of glaciation cycles. This hypothesis is testable as it predicts a south-to-north phylogenetic sequence of relationships, which would culminate in the recent origin of high Andean populations D. sexcinctus and D. leopardinus in the Provincia of Mendoza, Argentina.

ACKNOWLEDGMENTS

The following people and institutions facilitated individuáis of Diplolaemus: F. Troncoso (Museo Regional de Concepción); M.I. Christie (Sociedad Naturalista Andino Patagónica); J. Langone (Museo de Historia Natural de Montevideo); C. McCarthy (British Museum of Natural History); R. Günther (Museum für Naturkunde); H. Núñez (Museo Nacional de Historia Natural de Santiago de Chile); E. Pereyra (Instituto de Biología Animal. Universidad Nacional de Cuyo). A.R. Young, H. Ibarra-Vidal and F. Torres helped during feld work. E.M. Habit provided comments on the manuscript and helped obtaining part of the material in the Laguna del Laja National Park. Two anonymous reviewers provided valuable suggestions on an earlier versión of this contribution. Financial support was provided by the U.S. National Science Foundation (OISE 0530267 to PFV), Universidad de Concepción’s Research División grants 92.38.24-1, 96.113.040-1 and.205.113.067-lsp, and FONDECYT 1090664. Collecting permits in Chile were provided by CONAF.

BIBLIOGRAPHY

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Appendix 1

List of specimens examined in the present study. Specimens are deposited in the foliowing institutions: Alemania: Zoologischen Museum Berlín (ZMB); Argentina: Instituto de Biología Animal, Universidad Nacional de Cuyo (IBA) and Patagonian Andean Naturalist Society of San Carlos de Bariloche (MIC); Chile: Museo de Zoología de la Universidad de Concepción (MZUC), Museo Nacional de Historia Natural de Santiago (MNHN) and Museo Regional de Concepción (MCR); Inglaterra: British Museum Natural History (BMNH); and Uruguay: Museo Nacional de Historia Natural de Montevideo (MNHM).

Diplolaemus darwinii Bell, 1843: BMNH-0064, leptotype, adult male, Puerto Deseado, Puerto Deseado Department, Santa Cruz Province, Argentina, 1833. MNHN-CN1040, adult female, Ultima Esperanza Province, Magallanes y la Antártica Chilena Región, Chile, 12-1-1953. IBA9241, 9242, adult males, Bosque Petrifcado, Puerto Deseado Department, Santa Cruz Province, Argentina, 1-1973. IBA612, juvenile male, Estancia Esperanza, Santa Cruz Province, Argentina, 15-1-1970. IBA5221, 5222, adult females, 10 km north of Gobernador Gregores, Río Chico Department, Santa Cruz Province, Argentina (no date). IBA5223, juvenile female, 10 km north of Gobernador Gregores, Río Chico Department, Santa Cruz Province, Argentina. IBA6131, adult male, Estancia Carlota, Santa Cruz Province, Argentina, 20-1-1970. IBA6132, juvenile, Estancia Carlota, Santa Cruz Province, Argentina, 20-1-1970.

Diplolaemus bibronii Bell, 1843: BMNH-0013, leptotype, adult male, Puerto Deseado, Puerto Deseado Department, Santa Cruz Province, Argentina, 1833. BMNH-0010, 0011, paraleptotypes, adult females, Puerto Deseado, Puerto Deseado Department, Santa Cruz Province, Argentina, 1833. BMNH-0012, paraleptotype, adult male, Puerto Deseado, Puerto Deseado Department, Santa Cruz Province, Argentina, 1833. MCR-R0331, adultfemale, Chile Chico, General Carrera Province, Aisén del General Carlos Ibáñez del Campo Región, 15-1-1982. MZUC-6978, adult male, Santa Cruz Province, Argentina, I- 1985. MZUC-8968, adult female, Comodoro Rivadavia, Escalante Department, Chubut Province, Argentina, 29-X-1968. MZUC-23202, 23204, adult males, Chile Chico, General Carrera Province, Aisén del General Carlos Ibáñez del Campo Región, Chile, 24-11-1977. MZUC-23203, adult male, Río Mayo, Río Senguer Department, Chubut Province, Argentina, 27-11-1977. MNHM-01369, adult male, Punta Cavendish, Puerto Deseado, Puerto Deseado Department, Santa Cruz Province, Argentina, 9-XI-1965. MNHM-01654, 05823, adult males, Santa Cruz Province, Argentina, 23-1-1967. MNHM-03381, adult male, El Calafate, Lago Argentino Department, Santa Cruz Province, Argentina, 23-1-1967. MNHN-CN1502, adult female, Chile Chico, General Carrera Province, Aisén, del General Carlos Ibáñez del Campo Región, Chile, 15-XI-1983. MNHN-CN1501, 1503, 1505 adult males, Chile Chico, General Carrera Province, Aisén del General Carlos Ibáñez del Campo Región Chile, 5-XI-1983. MNHN-CN1743, adult female, Chile Chico, General Carrera Province, Aisén del General Carlos Ibáñez del Campo Región Chile, 22-X-1956. MNHN-CN1744, adult male, Chile Chico, General Carrera Province, Aisén del General Carlos Ibáñez del Campo Región Chile, 22-X-1956. MZUC-23328 - 23330, adult males, road between Perito Moreno and Río Mayo, Río Senguer Department, Chubut Province, Argentina, 14-11-1991. MZUC-23331, adult female, Chile Chico, General Carrera Province, Aisén del General Carlos Ibáñez del Campo Región, Chile, 16-11-1988. MZUC-23332, 23333, adult males, Chile Chico, General Carrera Province, Aisén del General Carlos Ibáñez del Campo Región, Chile, 16-11-1988. MZUC 053 Bosque Petrifcado, Puerto Deseado Department, Santa Cruz Province, Argentina, 1981. IBA921, adult female, Meseta Canquel, Paso de Indios Department, Chubut Province, Argentina, 1-1973. IBA909, adult male, Sierra Castillo, Chubut Province, Argentina, 1-1973. IBA9141, juvenile, Caleta Olivia, Deseado Department, Santa Cruz Province, Argentina, 1-1973. IBA9142, adult female, Caleta Olivia, Deseado Department, Santa Cruz Province, Argentina, 1-1973. IBA8111, 8112, adult females, Meseta Canquel, Paso de Indios Department, Chubut Province, Argentina, I-1972. IBA8113, juvenile, Meseta Canquel, Paso de Indios Department, Chubut Province, Argentina, 1-1972. IBA838, adult male, road between Las Horquetas and El Sombrero, Chubut Province, Argentina, 1-1972. IBA619, adult male, Valle Hermoso, Escalante Department, Chubut Province, Argentina, 22-1-1970. IBA915, adult male, road between Las Horquetas and El Sombrero, Chubut Province, Argentina, I-1972. IBA922, adultfemale, Manantiales, Chubut Province, Argentina, 1-1973. IBA910, adult male, Laguna Payahile,

Chubut Province, Argentina, 1-1972. IBA513, adultfemale, Meseta Somuncurá, 9 de Julio Departament, Río Negro Province, Argentina, 18-11-1968. IBA8011, adult male, road between Paso de Indios and El Sombrero, Paso de Indios Department, Chubut Province, Argentina, 15-1-1972. IBA8012, adult female, road between Paso de Indios and El Sombrero, Paso de Indios Department, Chubut Province, Argentina, 15-1-1972. IBA8013, juvenile, road between Paso de Indios and El Sombrero, Paso de Indios Department, Chubut Province, Argentina, 15-1-1972. IBA451, juvenile, between Caleta Olivia and Fitz Roy, Deseado Department, Santa Cruz Province, Argentina, 26-12-1967. IBA6211, 6212, adult males, San Julián, Magallanes Department, Santa Cruz Province, Argentina, 13-1-1970. IBA923, adult male, Laguna Madre e Hija, Puerto Deseado Department, Santa Cruz Province, Argentina, 1-1973.

Diplolaemus leopardinus (Werner), 1898: ZMB-13395, holotype, adult male, Santiago {in error), 1893-1895. IBA8121, 8122, adult females, Payún, Malargüe Department, Mendoza Province, Argentina, 28-1-1972. IBA926, adult male, Tunuyán, Tunuyán Department, Mendoza Province, Argentina, 12-1-1973. IBA1177, adult male, 80 km south of Nihuil, San Rafael Department, Mendoza Province, Argentina, (no date). IBA7761, 7762, adult males, Payún, Malargüe Department, Mendoza Province, Argentina, 6-XII-1971. IBA9251, 9252, adult females, Volcán Payún, Malargüe Department, Mendoza Province, Argentina, III-1973. IBA371, juvenile, Santa Clara, Tupungato Department, Mendoza Province, Argentina 12-1-1967. IBA911, juvenile, Volcán Payún, Malargüe Department, Mendoza Province, III-1973. IBA372, juvenile, El Portillo, Tunuyán Department, Mendoza Province, Argentina, 27-11-1966.

Diplolaemus sexcinctus Cei, Scolaro & Videla, 2003: MZUC-23303, adult male, slope of Antuco Volcano, Laguna del Laja National Park (37° 2VS - 71° 19"W, at 1,300 m of altitude), Biobío Province, Biobío Región, Chile, collected by P Victoriano and E. Habit, 14-111-1992. MZUC-23302, adult female, slope of Antuco Volcano, Laguna del Laja National Park (37° 2LS - 71° 19" W, at 1,300 m of altitude), Biobío Province, Biobío Región, Chile, collected by P Victoriano and J.C. Ortiz, 15-11-1987. MZUC-8765, 23324 -25, adult females, Petronquines, East of Laja Lake, Biobío Province, Biobío Región, Chile, collected by R. Donoso-Barros, 5-II-1970. MZUC-8373, 23319, 23322, juveniles, Lonquimay, Pino Hachado, Malleco Province, Araucanía Región, Chile, collected by L. Peña, XII-1961. MZUC-11306, 23327, adult females, Marimeñuco, Alto Biobío, Biobío Province, Biobío Región, Chile, collected by R. Donoso-Barros, XII-1969. MZUC-23192, adult female, Nuble National Reserve, Butamayín Pass, Ñuble Province, Biobío Región, Chile, collected by V Quintana, 26-XI-1993. MZUC-23291-92, 23294, 23298, 23300, adult males, Picontreñe, East of Laja Lake, Biobío Province, Biobío Región, Chile, collected by P. Victoriano, 31-1-1987. MZUC-23295, juvenile in Picontreñe, East of Laja Lake, Biobío Province, Biobío Región, Chile, collected by P. Victoriano and J.C. Ortiz, 31-1-1987. MZUC-23296-97, adult females, Picontreñe, Eastof Laja Lake, Biobío Province, Biobío Región, Chile, collected by P. Victoriano, 1-1987. MZUC-23299, adult females, Picontreñe, East of Laja Lake, Biobío Province, Biobío Región, Chile, collected by E. Habit, 31-1-1987. MZUC-23304, adult male, slope of Antuco Volcano, Laguna del Laja National Park, Biobío Province, Biobío Región, Chile, collected by P. Victoriano, 15-11-1987. MZUC-23305, adult female, Antuco Volcano, National Park Laguna del Laja, Biobío Province, Biobío Región, Chile, collected by P. Victoriano, 15-11-1987; MZUC-23306, adult female, Las Playas, Laguna del Laja National Park, Biobío Province, Biobío Región, Chile, collected by H. Ibarra, 17-11-1987. MZUC-23307, adult female, Piedra del Indio, East of Laja Lake, Biobío Province, Biobío Región, Chile, collected by E. Habit, 15-11-1987. MZUC-23309, adult male in Los Barros, at 1 km east of the slopes of Antuco Volcano, Biobío Province, Biobío Región, Chile, collected by P. Victoriano, 6-XII-1986. MZUC-23310, adult female, Las Playas, Laguna del Laja National Park, Biobío Province, Biobío Región, Chile, collected by P. Victoriano, ll-XI-1987. MZUC-23311-12, adult females, Las Playas, Laguna del Laja National Park, Biobío Province, Biobío Región, Chile, collected by P. Victoriano, 17-11-1987. MZUC-23313, adult male, Alto Biobío, Shore of IcalmaLake, Malleco Province, Araucanía Región, Chile, collected by J.C. Ortiz, 17-111-1990. MZUC-23315,23318,23321, adult males, Lonquimay, Pino Hachado Pass, Malleco Province, Araucanía Región, Chile, collected by L. Peña, XII-196L.MZUC-23316, adult female, Lonquimay, Pino Hachado Pass, Malleco Province, Araucanía Región, Chile, collected by L. Peña, XII-1961. MZUC-23323, 23326, adult males, Petronquines, shore of Laja Lake, Biobío Province, Biobío Región, Chile, collected by R. Donoso-Barros, 5-II-1970. MIC-006, adult male, Llao Lleo River, Neuquén Province, Argentina, collected by M. Christie, 22-XI-1987. MIC-007, adult male, Caña Plantada, road to Río Malleo, Neuquén Province, Argentina, collected by I. Belke, 20-III-1983. MIC-011, juvenile, Caña Plantada, Lanín National Park, Neuquén Province, Argentina collected by PH. Borraz, 14-11-1983 MIC-028, juvenile, en Huechulafquén National Park, Huiliches Department, Neuquén Province, Argentina, collected by D. Vega, 17-11-1983. MIC-046, juvenile, near Rucachoroi Lake, Lanín National Park, Aluminé Department, Neuquén Province, Argentina, collected by I. Belke, 20-11-1983. MIC-075, juvenile, Chapelco range, Lácar Department, Neuquén Province, Argentina, collected by B. Feingold, 20-111-1983. MIC-077, juvenile, Traful Sectional Pass, Los Lagos Department, Neuquén Province, Argentina, collected by M. Buttini, 19-1-1983. MIC-081, adult female, Huechulafquén National Park, Huiliches Department, Neuquén Province, Argentina, collected by D. Vega, 17-11-1983. MIC-082, 084 adult females, Cerro Trujillo, Aluminé Department, Neuquén Province, Argentina, collected by I. Belke, 26-11-1983. MIC-083, 085, juveniles, Cerro Trujillo, Aluminé Department, Neuquén Province, Argentina, collected by I. Belke, 26-11-1983. MIC-089, adult female, Cerro Otto, Bariloche Department, Río Negro Province, Argentina, collected by D. Bettinelli, 16-IV-1984. MIC-762, adult female, Lago Caviahue Aerodrome, Ñorquín Department, Neuquén Province, Argentina collected by I. Christie, 1-II-1988. MIC-890, adult female, Río Agrio Bridge, Ñorquín Department, Neuquén Province, Argentina, collected by M. Christie, 1-II-1988. MIC-1080, adult female, Laguna Blanca, Zapala Department, Neuquén Province, Argentina, 17-111-1994. MIC-1110, adult male, Cerro Las Ardillas, Nahuel Huapi National Park, Río Negro/Neuquén Province, Argentina, collected by M. Christie, 2-II-1994. MIC-1144, adult female, in Cerro Las Ardillas, Nahuel Huapi National Park, Río Negro/Neuquén Province, Argentina, collected by M. Christie 21-XII-1994. MIC-1174, adult female, Portal La Atravesada, Neuquén Province, Argentina, collected by M. Christie 15-11-1995. MIC-1176, adult male, Portal La Atravesada, Neuquén Province, Argentina, collected by M. Christie, 15-11-1983. MIC-1185, adult female, in Zapala Station, Zapala Department, Neuquén Province, Argentina, collected by M. Christie 15-11-1995. MIC-1196, 1202, adult females, Los Lagos Department, Neuquén Province, Argentina, collected by M. Christie 9-III-1995.


Recibido: 06.08.09

Aceptado: 25.05.10