Kora

According to Eric Charry,

West African harps are spike harps, wherein the neck is spiked all the way through the resonator. Using the resonator as a distinguishing feature there are two main kind of W. A. harps: those with clabash (gourd) resonators, which are primarily found in the savannah region, and those with wooden box resonators, primarily found farther south in the forest regions.

Using the social function of a harp as a distinguishing feature, three kinds of calabash resonator harps may be distinguished:

From your description it sounds like you have a bolon or maybe one of the hunters' harps.

I'm especially fond of the donso ngoni clip above...

Kora sound example

Kora instrument photos

21-string:

 

22-string:

Cora Schematic Diagram:

Some Still Pictures of Kora players:

Kausu Kuyateh and Dembo Konte. Kuyateh adds extra bass strings to the kora, making a version with 23 strings. He plays in the Yeyengo style, which originated in the Kabou tradition and is played in the kora tuning know as Tomora Ba, which is a sort of blues version of the Dorian mode.

 

Toumani Diabiate (in addition to his traditional recordings) has recorded with a Spanish Flamenco group "Ketama".

Some Kora Links 

Gambia (21 string) Cora Connection: Kora Pictures
 Music catalog (with sound example and a movie)  Cora Connection: West African Music Catalog
Buying a calabash to make a new Kora Jali Madi Suso goes to market
Tuning the Kora  Tuning The Kora
Sound examples  Cora Connection: Discover The Mandinka Kora
discussion with examples West African Music 
Jaliba Kuyateh  Jaliba Kuyateh
Kora samples & CD info  ARP Music - Two Kora Players of the Gambia
Toumani Diabate  Music From Mali's Grand Prince of Kora
Moussa Kanoute (audio)  Dance of the Kora