By Reuters Staff (Adds details) JOHANNESBURG, Aug 4 (Reuters) - South Africa’s third-biggest telecom company Telkom said on Wednesday it has appointed the head of its consumer business, Serame Taukobong to be group Chief Executive Officer designate with effect from Oct. 1. Taukobong, who is also a group Executive Committee Member, replaces Sipho Maseko who will step down at the end of June next year. Taukobong joined Telkom in June 2018 and has extensive experience in telecommunications having spent about 10 years at rival MTN Group, where he held several senior roles which included Chief Operating Officer and later CEO of MTN Ghana, Telkom said.