A MAYFLY FROM TROPICAL BRAZIL CAPABLE OF TOLERATING SHORT-TERM DEHYDRATION

The mayfly Cloeodes hydation (Baetidae, Ephemeroptera) inhabits epheme ral, rain-filled rock pools as well as pools, springs, and brooks of l onger duration in savanna woodlands of the northern Pantanal region, B razil. Larvae have the ability to tolerate repeated exposure to air fo r up to 9 h at a time, as confirmed by laboratory experiments. This to lerance is apparently advantageous in the highly dynamic, unpredictabl e habitat conditions, especially when pools are successively wet and d ry almost daily during the end of the rainy season. Survival of larvae depended on the presence of sediment, and was always followed by moul ting. Inducible and repeated moulting showed that numbers of moults an d instars were not always indicative of development. We present data o n C. hydation abundance in 2 rock pools throughout 1 y. From these dat a, larval development was estimated to require between 19 and 25 d (24 -29 degrees C).