INTEGUMENTARY STRUCTURE AND ITS RELATIONSHIP TO WIPING BEHAVIOR IN THE COMMON INDIAN TREE FROG, POLYPEDATES MACULATUS

Skin of the Indian tree frog, Polypedates maculatus (Rhacophoridae), w as studied in the context of self-wiping behaviour which functions to expel and distribute cutaneous secretions recently shown to retard eva porative water loss. The secretions contain both mucus and lipids and are derived from a common gland considered to be homologous with chara cteristic anuran mucous glands. The glands are bipotent and secrete bo th mucus and lipoid products which are evidently mixed within the glan dular lumen. Another type of gland resembling characteristic anuran se rous (or granular) glands is found in dorsal but not ventral skin, whe reas the lipid-secreting mucous glands are found in skin associated wi th all body surfaces. There is no distinct, lipid-secreting gland pres ent in the skin of this species other than the mucous glands. These hi stochemical data complement the earlier finding that resistance to eva porative water loss in this species is relatively small compared with phyllomedusine 'waterproof' frogs which also exhibit wiping behaviour associated with secretion of lipids. Thus, wiping behaviour may have e volved in association with mucous secretions before dominant lipoid se cretions resulted from strong selection for water conservation.