“43rd Annual Academy of Country Music Awards” (8 p.m., CBS): Reba McEntire brings her

“43rd Annual Academy of Country Music Awards” (8 p.m., CBS): Reba McEntire brings her country charm and humor to center stage as she returns for the 10th time to host the awards show, airing live from the MGM Grand in Las Vegas. Among those scheduled to perform: Trace Adkins, Brooks Dunn, Kenny Chesney, Rascal Flatts, Miranda Lambert, Brad Paisley, George Strait, Taylor Swift, Carrie Underwood and Keith Urban.

“Expedition: Guyana” (8 p.m., Discovery): With oversize wildlife and a habitat that includes rain forests and savannas, Guyana remains one of the planet’s most biodiverse regions. A team of filmmakers and scientists visited the South American country to document its rare and unique species, some previously unknown to mankind. This special looks at the team’s mission, which the explorers hope will demonstrate the need for conservation, even as Guyana may open 1 million acres of its territory to logging.

“Mystery of the Crystal Skulls” (9 p.m., Sci Fi): The legends and lore surrounding a group of quartz crystal skulls — as featured in the “Indiana Jones” film hitting theaters this week — are explored in this new special, hosted by NBC’s Lester Holt. Legend has it that the scattered skulls — which have been linked to Mayan and Aztec ruins — supposedly will reveal secrets crucial to humankind’s survival if they ever are united. The special looks at scientific tests and an expedition to Belize in search of the missing skulls. Before the special, Sci Fi will air the first three “Indiana Jones” films beginning at 1 p.m.

“Carlos Mencia: Performance Enhanced” (9 p.m., Comedy Central): Funnyman Carlos Mencia is back with a new stand-up special. Filmed in Hollywood, Fla., “Carlos Mencia: Performance Enhanced” is fortified with his irreverent takes on politics, race and culture.