Description of Morphological Abnormalities in Rhinella Arenarum (ANURA: BUFONIDAE)

THIEME 44 Original Article

Description of Morphological Abnormalities in Rhinella arenarum (ANURA: BUFONIDAE)

P.D. Chilote1 L.E. Bozzolo2 F.R. Gutierrez1 L.E. Moreno1,2,Ã

1 Zoology Department, Faculty of Chemistry, Biochemistry and Address for correspondence L.E. Moreno, National University of Pharmacy, National University of San Luis – UNSL, Chacabuco y San Luis – UNSL, Chacabuco y Pedernera, San Luis, 5700, Argentina Pedernera, San Luis, Argentina (e-mail: [email protected]). 2 Vertebrate Functional Morphology, Zoology Department, Faculty of Chemistry, Biochemistry and Pharmacy, National University of San Luis – UNSL, Chacabuco y Pedernera, San Luis, Argentina

J Morphol Sci 2018;35:44–47.

Abstract The rise of anatomical abnormalities in anurans over recent years has increased the interest in producing more and better information about the abnormalities observed in specimens within natural environments that are currently being altered. The aim of this work was to identify and describe la osseous abnormalities found in Rhinella arenarum. Four samplings were conducted between March 2009 and February 2010 in the Claro river, located in San Francisco in the Ayacucho Department in the province of San Luis. Specimens of R. arenarum with visible abnormalities were observed and collected manually. They were euthanized in the laboratory, preserved in 10% formaldehyde, and stored in the Herpetological Collection Unit of the National University of San Luis (CH- UNSL). The Alizarin-Alzian technique was also applied to the specimens. Photographs of Keywords the abnormalities were taken, and observations were made with a stereoscopic

► abnormalities microscope. The following abnormalities were identiﬁed and described: femur ectro- ► rhinella arenarum melia, tibial and ﬁbular ectromelia, ectrodactylia and brachydactyly. Further work ► brachydactyly could focus on determining the causes of the abnormalities observed in this species, ► ectrodactylia conducting an integrated study, and attempting to link this with the worldwide ► ectromelia phenomenon of amphibious declination.

Introduction development, traumatic factors, and particularly, knowledge regarding the variation in abnormality rates across species, Amphibians are considered good indicators of healthy envir- life stages, types of habitat, and geographical areas remain – onments.1 3 Reports on amphibian deformations have unexplained, thus making the identification of differences increased dramatically in recent years.4 The causes and between natural and artificial abnormalities problematic.11 implications of these abnormalities remain poorly explained, There is evidence of anuran specimens with supernumer- but several researchers have suggested they may indicate an ary extremities in Argentina.24 The interest in dealing with emerging threat for populations of amphibians and other this issue has grown in recent years in Argentina due to the – – forms of life.5 7 increasing number of anurans with abnormalities.20,25 30 Several causes or groups of causes are proposed as origi- These findings have also occurred in the province of San – nators of abnormalities in amphibians, including UV-B radia- Luis.31 33 Consequently, the objective of this work was to – – – tion,8 10 trematodes(,11 14 retinoids,6 pesticides,15 17 other identify and describe the abnormalities found in Rhinella – chemical pollutants18 21 and predation.22,23 However, arenarum from a natural environment in the province of San knowledge about the abnormalities resulting from heredity, Luis.

received DOI https://doi.org/ Copyright © 2018 by Thieme Revinter December 6, 2016 10.1055/s-0038-1660489. Publicações Ltda, Rio de Janeiro, Brazil ISSN 2177-0298. Morphological Abnormalities in Rhinella arenarum Chilote et al. 45

Materials and Methods Description of the Site and Natural History The work was conducted in the Claro river, one of the main tributaries of the San Francisco river, in the town of San Francisco (S 32° 36.7771 - WO 66° 08.0357), Ayacucho Department, province of San Luis. San Francisco del Monte de Oro is located to the North of the province, in a valley framed by the Sierras Centrales and the Socoscora hills. One of the characteristics of this area is the presence of Caranday palms (Trithrinax campestris), surviving in the Southern most habitat for this species. The climate is dynamic, with strong daily and seasonal temperature ﬂuctuations. During summer, the temperature ranges between 17°C and 38°C. Nights are often cold in winter, with minimal temperatures below 0°C. However, daytime temperatures are temperate, ranging between 15°C and 20°C.

Sampling Method Four nocturnal samplings were made between March 2009 and February 2010, and six abnormal specimens of Rhinella Fig. 1 Juvenile specimen with ectromedia. arenarum (2 juveniles and 4 adult individuals) were observed and collected. Specimens were collected using the Collection by Visual Encounters method (CVE), described traces were also observed. The ﬁbula presents a slight 34 by Crump and Scott Junior. curvature in relation to the left limb (►Fig. 3). CH-UNSL0434 Adult specimen: Brachydactyly and ectro- Laboratory dactylia of the right hindlimb. Digit I presents one pha- Specimens were taken to the laboratory, euthanized with an lanx, and digit IV presents 2 phalanxes. Complete absence MS-222 solution, ﬁxed with 10% formaldehyde, and stored in of digit V. The prehallux is cartilaginous in both limbs the Herpetological Collection Unit of the National University (►Fig. 4). of San Luis (CH-UNSL: 0431; 0432; 0433; 0434; 0435 and CH-UNSL0435 Adult specimen: Brachydactyly of the right 0436). Differential staining of cartilage, bone and subsequent hindlimb. Digit III has 2 phalanxes, the last of which is diafanization these animals was apply according to the technique developed by Wassersug.35 All observations were made using a stereoscopic microscope (Olympus SZ51). Photographs of the abnormalities found were taken with a digital camera (Canon EOS Rebel T5).

Morphological Analysis and Terminology The abnormalities observed were described according to the terminology proposed by Meteyer.36 We adhered to Fabrezi and Goldberg37 for the description of skeletal structures.

Results and Discussion

CH-UNSL0431 Juvenile specimen: Ectromelia of the right hindlimb (►Fig. 1). CH-UNSL0432: Juvenile specimen: Ectrodactylia of the left hindlimb. Absent metatarsal bone in digit V, curved digit III and digit II, and merged cartilages. It is not possible to differentiate digit I from digit II, although associated with these there are two phalanges and an ossiﬁed distal phalanx with a more robust appearance than that observed in the right limb with normal development. Absence of prehallux (►Fig. 2). CH-UNSL0433 Adult specimen: Ectrodactylia of the right back limb. Complete absence of metatarsal bones and digits, except for the prehallux. Undetermined ossiﬁed Fig. 2 Young specimen with ectrodactylia.

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Fig. 3 Ectrodactylia of the right back limb.

Fig. 6 with ectromelia in the tibiaﬁbula of the left back limb.

natural areas.6,7,12 However, the causes of these morpholo- Fig. 4 Detail of the right back limb with brachydactyly and gical abnormalities have not yet been identified. This makes ectrodactylia. it difficult to determine the difference between natural abnormalities and anthropogenic abnormalities.11 We have examined unilateral abnormalities in the hind extremities in this study, which coincides with findings of

studies conducted by Ouellet et al.7 and Johnson et al.12 However, while the most frequent abnormalities reported in the literature are additional extremities (polymelia),6,7,38 or reduced limbs (hemimelia),11 we did not observe these abnormalities. The variation of abnormalities in the limbs recorded in this study suggest etiological heterogeneity.

Conclusion

These cases may represent the first documented report of morphological abnormalities in an anuran population of San Luis North area, in Argentina. We believe it is important to establish precedents for abnormalities in different anuran Fig. 5 Adult specimen with brachydactyly. populations to document the increase of occurrence rates and abnormality recurrence. forked; digit IV has 2 phalanxes, and the last one is forked, swollen and cartilaginous (►Fig. 5). Collection Permission CH-UNSL0436 Adultspecimen: Ectromelia in the tibiofibula The collection of the Rhinella arenarum specimens that were of the left hindlimb, where only the proximal portion of the used to conduct this study was authorized by Resolution N° ossified and strong tibial and fibular traces are observable. 2525 of the Biodiversity Program of San Luis Province. The basal portion of the tibiofibula in the lateral view is swollen and shorter than the normal tibiofibula (►Fig. 6). Acknowledgments This work was funded by the PROICO 2–3514, National All the abnormalities observed were located in the hindlimbs. University of San Luis. The authors want to thank Romina The most common abnormality was ectrodactylia, followed by Marti and Juan Manuel Pérez Iglesias for their help in the brachydactyly and ectromelia. Multiple abnormalities in a samplings; we likewise want to thank Susana Trípole and singlelimbwere observed in one specimen. The cases recorded Patricia Garelis for promoting discussion and providing us present different forms in a single abnormality. with unconditional support. The authors appreciate the The abnormalities in the hindlimbs of the captured speci- comments and suggestions of anonymous reviewers who mens are the most common abnormalities observed in substantially improved the manuscript.

Journal of Morphological Sciences Vol. 35 No. 1/2018 Morphological Abnormalities in Rhinella arenarum Chilote et al. 47

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