Tail Bifurcation Incidence in Liolaemus Lizards Assessed through Citizen Science and Naturalist Notes

Abstract. Tail bifurcation in lizards is caused by an anomalous regeneration process after tail autotomy. A recent review shows that nearly half of the records came from social media and one of the less represented families was Liolaemidae (one case). The genus Liolaemus is mostly distributed along countries in the southern Andes, which have low numbers of tail bifurcation reports. Is the low incidence of tail bifurcation in Liolaemus a real biological phenomenon, or just a sampling artifact? Due to the lack of targeted searches and the large number of species on this group, we expect that an extensive survey will significantly increase the number of cases. We reviewed the scientific literature, internet sites, and social media (Instagram, Facebook, Flickr, and iNaturalist, 2020) using search terms in Spanish, Portuguese, and English. We found 16 tail bifurcation events corresponding to seven species, including a novel field observation. All bifurcations occur on the distal half of the tail congruently with described trends. Liolaemus tenuis was the most commonly recorded species, which could be explained by its presence in urban and natural areas. The same oversampling bias might affect the geographic distribution of all records. Our field observation might correspond to the first documented re-sight of a lizard with bifurcated tail. With the majority of records from social media, this study exemplifies the relevance of citizen science to document rare events. But, at the same time, it is a warning call for the need of more academic validation of the natural history and museum-based work.