Moq setup for a method that takes base class parameter

gistfile1.cs

public class when_car_was_stolen: claim_fixture
        {
            Because of = () =>
            {
                model.Risk = RiskTypes.Theft;
                responsibleGuid = responsibleId;
                workitemRepo.Setup(x => x.Add(MockIt.Is<SendEmailWorkItem>(wi => wi.ResponsibleId == responsibleGuid))).Verifiable();
                workitemRepo.Setup(x => x.Add(MockIt.Is<WorkItem>(wi => wi.TaskType == (int)TaskTypes.CreateClaim && wi.ResponsibleId == responsibleGuid))).Verifiable();
                controller.DamageClaim(model);
            };

            private It should_add_new_claim_workitem = () =>
            {
                workitemRepo.Verify(x => x.Add(MockIt.Is<WorkItem>(wi => wi.TaskType == (int)TaskTypes.CreateClaim)), Times.Once());
            };
            private It should_add_security_service_notification_workitem_with_same_responsible_as_new_claim = () =>
            {
                workitemRepo.Verify(x => x.Add(MockIt.Is<SendEmailWorkItem>(wi => wi.ResponsibleId == responsibleGuid)), Times.Once());
            };

            private static Guid responsibleGuid;
        }