Query WTPart using SUBTYPE NAME

I previously queried WTPart using subtype reference:-

TypeDefinitionReference typeDefRef = TypedUtility.getTypeDefinitionReference("subtypename"));

  sc = new SearchCondition(WTPart.class,  "typeDefinitionReference.key.id", SearchCondition.EQUAL,  typeDefRef.getKey().getId());

however i now have a requirement to query this using subtype name directy as in:-

sc = new SearchCondition(WTPart.class, -----  WTPart.Subtype ------, .......);

is it possible?