Delphon (species)

The Delphon were a species which communicated using the movement of their eyebrows. This was because the Fendahl Predator, a memeovore that fed on concepts, ate their ability to communicate. (PROSE: The Taking of Planet 5) The TARDIS' translation circuits were unable to translate non-verbal languages such as theirs. (AUDIO: The Havoc of Empires)

The Doctor was able to say the phrase "How do you do?" in their language. (TV: Spearhead from Space, AUDIO: ...ish) During the early portions of his Third incarnation, the Doctor couldn't say anything beyond that phrase. (AUDIO: The Blame Game) He apparently learned the full language sometime later on Alpha Centauri Five, and was then fluently able to translate their communication. (AUDIO: The Havoc of Empires)

Biology
They are described as being grey creatures with two rows of red eyes running down from forehead-to-chin with dark, spikey hair above each eye. (AUDIO: The Havoc of Empires) This species also found the amputation of limbs to be sexually attractive. (PROSE: Lucifer Rising)

History
During the diplomatic marriage between the leader of Chalnoth Hegemony and the director of the Teklarn Incorporation, the Delphon were suspected of attempted sabotaging the ceremony. This culminated in a Delphon fleet approaching Harmony Station, where the wedding was taking place. With the help of the Doctor, it was determined that the Delphon were invited to the wedding by diplomat Janus Perel, the real saboteur. (AUDIO: The Havoc of Empires)

The Third Doctor encountered the Delphons with Liz Shaw at some point after they had defeated the Nestenes. (PROSE: The Scales of Injustice)

During the War in Heaven, Homunculette incited the locals of Delphon into an attack against the enemy. It ended disastrously. (PROSE: The Taking of Planet 5)