Fungus spider (possible Beauveria sp. or Sugar Icing Fungus)
A spider caught by fungus. After a little research it would appear that this is likely to be a highly specific fungus, which only attacks the one species of spider – and it may be as specific as a species of huntsman (which this is). This is possible a species of Beauveria fungus which is similar to Metarhizium anisopliae. This is used to, among other things, attack the Australian plague locust. It seems likely that the spider gets infected by the fungus which then takes 10-14 days to kill it. It then continues to grow (like this) and will presumably produce some fruiting bodies. These may not be very prominent as a large mushroom growing out of a spider would probably have been noted by now.
Minyan falls, June 2009