Map<Id, Schema.RecordTypeInfo> recordTypeByIdMap = Schema.SObjectType.Contact.getRecordTypeInfosById();
Map<String,String> conversionMap = new Map<String,String>();
for(String r:recordTypeByIdMap.keySet())
{
    if(!recordTypeByIdMap.get(r).getDeveloperName().startsWithIgnoreCase('Create_'))
    {
        conversionMap.put('Create_'+recordTypeByIdMap.get(r).getDeveloperName(),r);
    }
}
System.debug('-------------'+conversionMap);