Non-Specialized Caudal Pseudoautotomy in the Emerald Racer Snake Drymobius Rhombifer (Günther, 1860)
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Herpetology Notes, volume 8: 567-569 (2015) (published online on 06 December 2015) Non-specialized caudal pseudoautotomy in the Emerald Racer snake Drymobius rhombifer (Günther, 1860) Dylan J. Padilla-Pérez1,2, Juan D. Murillo-Monsalve1, Edgar J. Rincon-Barón3 and Juan M. Daza1,* Tail breakeage among reptiles has been documented The long-tailed racers of the genus Drymobius have in sphenodonts, amphisbaenids, lizards but rarely in high frequencies of tail breakage, ranging between snakes (Arnold, 1984; Bellairs and Bryant, 1985). 14.3% in D. chloroticus and 21.7% in D. margaritiferus The ability to lose a body part grasped by an attacking (Mendelson, 1991). However, in the other two predator is an unambiguous antipredator mechanism species within Drymobius, tail breakage has not been (Formanowicz et al., 1990). This strategy in reptiles documented. occurs through one of two distinct form of urotomy: intravertebral breakage or intervertebral separation. For As part of an ongoing research program with the example, some lizards lose the tail spontaneously and aim of inventorying the herpetological diversity in the break is intravertebral, but the tail grows back, this northwestern Colombia (Ortiz-Yusti et al., 2015), method of tail loss is known as autotomy (Slowinski amphibians and reptiles have been collected and and Savage, 1995). In contrast to snakes, where the tail processed using standard protocols. In February 2015, breakage results from intervertebral separation requiring during a fieldwork in an area known as ‘‘La Arenosa’’, mechanical resistance and without tail regeneration, a pre-montane wet forest located at 1,278 m asl in the a condition known as pseudoautotomy (Todd and municipality of Alejandría, Department of Antioquia, Wassersug, 2010). Pseudoautotomy is further divided Colombia (6.39058°N, 75.03704°W), a male of D. either as specialized (having morphology that facilitates rhombifer was collected (MHUA-R 15012). The capture breakage), or non-specialized (where long and fragile occurred at 18:30 on the forest floor, crossing a muddy tails can break). High incidence of tail breakage has been zone. The specimen was collected with the intact tail observed in Coluber, Coniophanes, Dendrophidion, and kept alive overnight, in a thin cloth bag. In a photo Drymobius, Enulius, Natriciteres, Nerodia, Pliocercus, session the next day in a grass field, the specimen was Psammophis, Rhadinaea, Scaphiodontophis, very agitated after the photographer was holding it by the Sibynophis, Thamnophis (Mendelson, 1991; King, tail for a better place to take the photographs. The snake 1987; Broadley, 1987; Duellman, 1979; Hoogmoed and was observed to rotate quickly along its longitudinal Avila-Pires, 2011). axis in an attempt to escape from the observer causing the detachment of the tail (Figure 1). In this case, the tail twitched for approximately one minute after it became detached and the wound at the part attached to the body showed minimal bleeding (a small amount of blood 1 Grupo Herpetológico de Antioquia, Instituto de Biología, was visible at both wounds, but no blood was spilled). Universidad de Antioquia, Calle 67 # 53–108, Bloque 7–121, The break occurred between subcaudal pairs 64 and 65 A.A. 1226, Medellín, Colombia. and did not show the characteristic conical pieces of 2 Grupo de investigación Biodiversidad del Caribe Colombiano, muscle (segmented myomeres) that are present at the Programa de Biología, Facultad de Ciencias Básicas, anterior end of recently autotomized lizard tails (Zug et Universidad del Atlántico, Ciudadela Universitaria, Km 7, al., 2001; Pianka and Vitt, 2003:76). The tail fragment Antigüa vía a Puerto Colombia, Colombia. 3 Instituto de Biología, Universidad de Antioquia, Calle 67 # was preserved in 90% ethanol and stored for subsequent 53–108, Bloque 7–226, A.A. 1226, Medellín, Colombia tissue staining. The detached tail was lightly stained * Corresponding author e-mail: [email protected] with Alizarin red for bones, Alcian blue for cartilage 568 Dylan J. Padilla-Pérez et al. Figure 1. Tail breakage observed in an individual of Drymobius rhombifer (MHUA-R 15012). Site of tail breakage (A). Tail stained. Note that the anterior surface of the tail show the break point occurred between the vertebrae (B). Photos by DJ Padilla- Pérez (A) and JD Murillo-Monsalve (B). and partially cleared in KOH:Glycerol solutions of Auto 186 of 2014. We thank R.W. Henderson for his pre-review 25%, 50%, 70% proportions for 24 hours at each step. and comments to the manuscript. We also thank the Grupo Finally, it was transferred to 100% glycerol for imaging Herpetológico de Antioquia for its assistance in the field. to determine the break point that, in this case, was between the vertebrae (Figure 1). References The phenomenon of tail breakage in snakes has Arnold, E.N. (1984): Evolutionary aspects of tail shedding in lizards often been commented in the literature (Henderson, and their relatives. Journal of Natural History 18: 127-169. 1984; Savage and Crother, 1989) but the available Arnold, E.N. 1988. Caudal autotomy as a defense. 235–273. In: information concerning different species is far less Biology of the Reptilia. Volume 16. Gans, C. and R.B. Huey. than that available for lizards (Arnold, 1988). Within Eds. Alan R. Liss. New York. the genus Thamnophis, it has been observed that T. Bellairs, d’A., Bryant, S.V. (1985): Autotomy and regeneration in sirtalis do not tend to pseudoautotomize their tail unless reptiles. In: Biology of the Reptilia, p. 301-410. Development B, they are gripped by the tail alone, at which time they vol. 15. Gans, C., Billet, F., Eds. Wiley, Inc., New York. quickly rotate along their longitudinal axis. This rolling Broadley, D.G. (1987). Caudal autotomy in African snakes of the genera Natriciteres Loveridge and Psammophis Boie. Journal of behaviour and subsequent twitching of detached tails the Herpetological Association of Africa 33:18-19. has also been reported for T. cyrtopsis (Cooper and Cooper, W.E., Alfieri, K.J. (1993): Caudal autotomy in the Eastern Alfieri, 1993). Garter Snake, Thamnophis s. sirtalis. Amphibia-Reptilia 14: Partial tail loss during capture suggests that D. 86-89. rhombifer employs non-specialized pseudoautotomy Duellman, W.E. (1979). The biology of an equatorial herpetofauna as an anti-predator defense. Prolonged twitching of in Amazonian Ecuador. University of Kansas publications, a recovered tail supports this hypothesis (Todd and Museum of Natural History 65:1-352. Wassersug, 2010). Examination of the detached and Henderson, R.W. (1984). Scaphiodontophis (Serpentes: Colubridae): Natural history and test of a mimicry hypothesis, stained tail showed breakage was intervertebral. Although pp. 185-194. patterns of frequent tail loss have been described for D. Hoogmoed, M.S. and T.C.S. Avila-Pires. (2011). A case of chloroticus and D. margaritiferus (Mendelson, 1991), voluntary tail autotomy in the snake Dendrophidion dendrophis to our knowledge this is the first time pseudoautotomy (Schlegel,1837) (Reptilia: Squamata: Colubridae). Boletim do has been documented in D. rhombifer. Museu Paraense Emílio Goeldi. Ciências Naturais 6 (2): 113- 117. Acknowledgments. Fieldwork was funded by Isagen-UdeA King, R.B. (1987). Color pattern polymorphism in the Lake Erie under project 47/146. 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Slowinski, J.B., Savage, J.M. (1995): Urotomy in Scaphiodontophis: evidence for the multiple tail break hypothesis. Herpetologica 51 (3): 338-341. Todd, J. and R. Wassersug. (2010). Caudal pseudoautotomy in the Eastern Ribbon Snake,Thamnophis sauritus. Amphibia-Reptilia 31 (2010): 213-215. Zug, G.R., L.J. Vitt and J.P. Caldwell. (2001). Herpetology. An introductory biology of amphibians and reptiles: i-xiv, 1-630. Academic Press, San Diego. Accepted by Anamarija Zagar.