Richard K. (Dick) Stoneburner resigned as a director of Cub Energy Inc., the company said after he informed the board of directors Feb. 12. His resignation was effective immediately.

The announcement comes as Yuma Energy Inc. and privately held Davis Petroleum Acquisition Corp. said Feb. 12 that they have entered into a definitive merger agreement for an all-stock transaction. Stoneburner will be a non-executive chairman of Yuma after it merges with Davis Petroleum, Houston-based Yuma said.

"We thank Dick for contributions to our board and company. We wish him well," said Mikhail Afendikov, chairman and CEO of Cub Energy, which operates in the Black Sea and has offices in Houston, Calgary, Alberta, and Kiev, Ukraine.

Stoneburner has spent nearly four decades in the industry, including serving as president of BHP Billiton’s North America shale production division. He also led Petrohawk Energy Corp. from 2007-11 as president and COO.