April 23 (Reuters) - German biotech firm Evotec said on Tuesday it has appointed Christian Wojczewski as its chief executive officer, succeeding Werner Lanthaler who left after spending almost 15 years with the company.

Wojczewski, whose appointment is effective July 1, has more than 20 years of experience in various management positions, most recently as CEO of Dutch healthcare company Mediq and at Germany's Linde Healthcare.

The firm, which works in drug development with partners including Novo Nordisk, Bayer and Bristol-Myers Squibb, had said in January that Lanthaler would resign for personal reasons.

Later that month, the firm said it had immediately reported trades in its shares by its former CEO as soon as it was informed of the transactions that he had kept under wraps for up to three years.

After the issue was reported, German daily Handelsblatt said the country's financial regulator was looking into whether the former chief executive breached transparency obligations.

Mario Polywka, who has led Evotec as interim CEO since Jan. 3, will retire from his position at the end of June. (Reporting by Urvi Dugar in Bengaluru; Editing by Shilpi Majumdar)