(a) The surname of a limited partner shall not appear in the partnership name, unless:

(1) It is also the surname of a general partner; or

(2) Prior to the time when the limited partner became such, the business had been carried on under a name in which his surname appeared.

(b) A limited partner whose name appears in a partnership name contrary to subsection (a) of this Code section is liable as a general partner to partnership creditors who extend credit to the partnership without actual knowledge that he is not a general partner.