Herpetology Notes, volume 12: 363-364 (2019) (published online on 0April 2019)

Biofluorescent lateral patterning on the mossy bushfrog (Philautus macroscelis): the first report of biofluorescence in a rhacophorid

Russell J. Gray1

Biofluorescence occurs when organic material absorbs communication, and conspecific signalling (Arnold et short-wavelength electromagnetic radiation and re-emits al., 2002; Vukusic and Hooper, 2005; Michiels et al., part of the absorbed radiation at a longer wavelength. 2008; Gerlach et al., 2014; Taboada, 2017). Previous For humans, fluorescence is typically outside of the research on spectral sensitivity of treefrogs, such as visual spectrum and can only be detected with the Hyla cinerea, indicates the ability to perceive spectral assistance of UV-A light. Biofluorescence is well wavelengths of fluorescent emission under low-light documented in fauna throughout marine ecosystems; conditions (King et al., 1993). there are relatively few accounts of terrestrial fauna As the common name “Mossy Bushfrog” suggests, exhibiting biofluorescence. Recently, biofluorescence Philautus macroscelis are characterised by their green, has been a topic of interest among herpetofauna after the moss-like camouflage. If the can perceive discovery of fluorescence in sea turtles and chameleons fluorescent emissions under lowlight conditions, (Gruber and Sparks, 2015; Prötzel, et al., 2018). In other recent studies, biofluorescence was reported for the first time in an anuran through means of lymph and gland emissions in pigmentary cells (Taboada et al., 2017a). Shortly after, fluorescent emissions were also reported in Boana atlantica (Tabaoda et al., 2017b), and B. rufitelus (Deschepper et al., 2018). Here I document biofluorescence in another anuran: Philautus macroscelis (Boulenger, 1896). While surveying Kinabalu Park, Sabah, Malaysia for reptiles and on the nights of 4-7 November 2018 (6.0176 °N, 116.5373 °E, approx. 1649 m elevation), a Defiant UV LED handheld flashlight (395 nm) was used to shine each to check for signs of fluorescence. When Philautus macroscelis were illuminated, fluorescent markings on the sides of the body and inner thigh (Fig. 1) became visible. Although the significance of biofluorescence in is still not completely understood, many studies have concluded its potential for enhanced visual

Figure 1. Philautus macroscelis shown at night under (A) a flashlight, and (B) under UV light. Biofluorescent patterning 1 705 Alligator Ranch Rd., New Smyrna Beach, Florida, U.S.A., can be seen on the sides of the body and inner thigh. Photos 32168; author e-mail: [email protected] by Imran Khimji 364 Russell J. Gray the lateral patterning may serve as a visual signal to drives seasonal patterns of host use in mosquitoes. PLoS supplement acoustic signalling, while still remaining One 6:3 e17681. camouflaged from the dorsal view. Acoustic signalling Deschepper, P., Jonckheere, B., Matthys, J. (2018): A light in the dark: the discovery of another fluorescent frog in the Costa in increases risk of falling prey to predators, Rican rainforests. Wilderness & Environmental Medicine 29: parasitoids, and vector insects (McKeever, 1977; Tuttle 421–422. and Ryan, 1981; Bernal et al., 2006, 2007; Burkett- Gerlach, T., Sprenger, D., Michiels, N.K. (2014): Fairy Cadena et al., 2011). Non-acoustic signals could be wrasses perceive and respond to their deep red fluorescent beneficial for avoidance of these potential threats while coloration. Proceedings of the Royal Society B: Biological attracting a mate. Sciences 281: 1–7. Although the sex of frogs was not determined during Gruber, D.F., Sparks, J.S. (2015): First observation of fluorescence in marine turtles. American Museum Novitates 1: (3845) 1–8. the survey, both male and female Philautus macroscelis King, R.B., Douglass, J.K., Phillips, J.B., Baube, C.L. (1993): are known to have lateral patterning. If both males Scotopic spectral sensitivity of the optomotor response in and female P. macroscelis exhibit biofluorescence, the green treefrog Hyla cinerea. Journal of Experimental the characteristic could also be used as an additional Zoology 267: 40–46. morphological trait of the species. However, other McKeever, S. (1977): Observations of Corethrella feeding on tree than P. macroscelis, fluorescence in other species of frogs (Hyla)[Insect pests]. 0osquito News. Philautus was not examined during these surveys. Michiels, N.K., Anthes, N., Hart, N.S., Herler, J., Meixner, A.J., Schleifenbaum, F., et al. (2008). Red fluorescence in reef fish: a Taboada et al. (2017b) predicted that other potentially novel signaling mechanism?. BMC ecology 8: 16. biofluorescent species of frogs would likely exhibit Prötzel, D., Heß, M., Scherz, M.D., Schwager, M., van’t Padje, fluorescence based on high concentration of biliverdin, A., Glaw, F. (2018): Widespread bone-based fluorescence in translucent skin, and white peritonea. Although the chameleons. Scientific reports 8: 698. frogs examined during these surveys were not tested for Taboada, C., Brunetti, A.E., Pedron, F.N., Neto, F.C., Estrin, D.A., concentration of biliverdin, the species does have clear, Bari, S.E., et al. (2017a): Naturally occurring fluorescence in translucent patches on its side which do not exhibit frogs. Proceedings of the National Academy of Sciences 114: 3672–3677. florescence; the peritonea was not examined though Taboada, C., A. E. Brunetti, C. Alexandre, M. G. Lagorio, and it can be disqualified as the source of fluorescence in J. Faivovich. (2017b): Fluorescent frogs: A herpetological this particular species because the fluorescent portion of perspective. South American Journal of Herpetology 12: 1–13. the frog was opaque. Furthermore, the genus Philautus Tuttle, M.D., Ryan, M.J. (1981). Bat predation and the evolution of was not included as part of the Taboada et al. (2017b) frog vocalizations in the neotropics. Science, 214: 677–678. rhacophorid predictions. It is worth noting that this is the Vukusic, P., Hooper, I. (2005): Directionally controlled fluorescence first instance of biofluorescence exhibited in the family emission in butterflies. Science 310: 1151. , and the first documented instance of bioluminescent frog outside of the neotropics.

Acknowledgements. I would like to thank Imran Khimji for providing photos of frogs found on our surveys, including the two used in this note. I would also like to thank Antoine Pelletier, Kayden Phan and Imran Khimji for their assistance in surveys.

References

Arnold, K.E., Owens, I.P., Marshall, N.J. (2002): Fluorescent signaling in parrots. Science 295: 92. Bernal, X.E., Page, R.A., Rand, A.S., Ryan, M.J. (2007): Cues for eavesdroppers: do frog calls indicate prey density and quality? The American Naturalist 169: 409–415. Bernal, X.E., Rand, A.S., Ryan, M.J. (2006): Acoustic preferences and localization performance of blood-sucking flies (Corethrella coquillett) to túngara frog calls. Behavioral Ecology 17: 709– 715. Burkett-Cadena, N.D., McClure, C.J., Ligon, R.A., Graham, S.P., Accepted by Benjamin Tapley Guyer, C., Hill, G.E., et al. (2011): Host reproductive phenology