"The angle from which this photo has been taken makes it a bit difficult to see if there is a sharp ridge in the neck region (which would make it Ceratosoma trilobatum) or no ridge (which would make it Ceratosoma gracillimum). However there is at least some indication of a ridge, so I am more inclined to call it Ceratosoma trilobatum."
Comment from Richard Willan
The angle from which this photo has been taken makes it a bit difficult to see if there is a sharp ridge in the neck region (which would make it Ceratosoma trilobatum) or no ridge (which would make it Ceratosoma gracillimum). However there is at least some indication of a ridge, so I am more inclined to call it Ceratosoma trilobatum.