Xenotilapia sp. 'ochrogenys ndole' male displaying for a female in the aquarium - Photo by Christophe Drone.
The existence of a Xenotilapia species in the southern part of Lake Tanganyika with a close resemblance with X. ochrogenys has been known for a long time, as Max Poll already in 1956 mentioned a southern form of X. ochrogenys, which according to his description matches the cichlid we know today as X. sp. 'ochrogenys ndole'. Poll recorded Sumbu and Mbete in Zambia as find places (Poll 1956).
The German Walther Eysel found Xenotilapia sp. 'ochrogenys ndole' in Ndole Bay, Zambia in 1983, and in 1986 he successfully brought it back to Germany, introducing it to the aquarium hobby for the first time - in 1989 he also found X. sp. 'ochrogenys ndole' in Isanga Bay, Zambia (Eysel 1987; 1990).
Other localities where Xenotilapia sp. 'ochrogenys ndole' has been found are Kalambo at the border between Zambia and Tanzania and Utinta Bay in Tanzania (Forsberg 1997); recently a variant labelled Mzuri has been exported, that probably stems from southern Tanzania. Thus the distributional range of X. sp. 'ochrogenys ndole' properly encompasses most of the Zambian and part of the Tanzanian shoreline up to Utinta Bay, just north of Cape Mpimbwe.
Eysel noted that there is some geographical variation in Xenotilapia sp. 'ochrogenys ndole'; the males from Ndole Bay have a broad black margin on the ventral fins which are missing in the variant from Isanga Bay (Eysel 1990).
Xenotilapia sp. 'ochrogenys ndole' differ from X. ochrogenys in growing bigger, 14 cm vs. 11-12 cm in the latter, having a larger head with a steeper forehead and most conspicuous, the 3-5 black blotches along the flank of the fish, sometimes with additional black blotches in the dorsal fin and a broad black margin in the anal fin.
Xenotilapia sp. 'ochrogenys ndole' is here regarded as a potentially un-described species, but whether it’s in fact a new species, only time will tell, when somebody has examined and compared it with X. ochrogenys. The different distribution together with the morphological differences between the two is a topic that needs further investigation and until this has been done, I consider it best to refer to it as un-described species.
Addendum: After an examination of one of the syntypes of Stappersia singularis, which for a long time has been considered a synonym of Xenotilapia ochrogenys, it was clear that X. sp. "ochrogenys ndole" corresponded with Stappersia singularis. It was further shown that it represents a distinct species, reproductively isolated from X. ochrogenys, and was thus revalidated under the name of Xenotilapia singularis (Andersen, 2007). The distributional range encompass the southern part of lake Tanganyika between Kilewa Bay (D.R. Congo) and Kayla (Tanzania].
Link to Xenotilapia singularis in the CRC Catalogue.