I've finally managed to put together enough about an acquisition to be able to comment upon it with some detail. Belonging to the 'Kora" family the Goni is played by Dioula people of Burkina Faso. The instrument is very similar to Kamale Ngoni, though somewhat larger.
I got mine in June from Akili Gnouma a local musician - who treated me to an impromptu performance that day.
The tuning is also pentatonic: D-F-G-A-c-d-f-g left hand: D-G-c-f, right hand: F-A-d-f, there are 8 or 10 strings, expanding the tonal range over more than one octave.
The Goni is played solo for accompaniment of songs or together with the pentatonic Balafon of the region. Like the Kora, the Goni is played with thumbs and forefingers of both hands - played with the left thumb and forefinger and the right thumb. The dampening technique of the right thumb is used to stop the sound immediately after plucking the string.