Xenotilapia sp. 'fluorescent green' was previously thought to be a potentially undescribed species from the southern part of lake Tanganyika, but is now considered to represent X. nasus. A female from Chituta Bay [Zambia] in the aquarium is here shown Photo by Thomas Andersen. Determiner Thomas Andersen.
Xenotilapia sp. 'fluorescent green' was first discovered in 1993 by the well-known German aquarist and ichthyologist Heinz Büscher, while diving at the locality known as Tembwe II on the Congolese coast. It has since then been found in Zambia on several localities, the most well-known being Chituta Bay, where it lives sympatrically with X. nigrolabiata (Andersen 2005).
The closest relative of X. sp. 'fluorescent green' is properly X. nasus, that has been found in the extreme north of Lake Tanganyika and with which X. sp. 'fluorescent green' shares some characteristics with, among other things a protruding snout and the numbers of hard and soft spines in the anal and caudal fins. Some things differ though, as it seems that X. sp. 'fluorescent green' has a larger head and eyes (Andersen 2005).
Addendum: Xenotilapia sp. 'fluorescent green', was previously thought to be a potentially undescribed species occurring in the southern part of Lake Tanganyika (Andersen 2005), it is now considered to belong to X. nasus, described from the northernmost part. After an examination of the types of X. nasus at the Africa Museum, Tervuren [Belgium] it became evident that X. sp. “fluorescent green” were very similar to X. nasus, as only minor differences in morphology were detected, and with an identical coloration (Andersen 2012). Further direct observations of X. nasus at Kigoma has shown that the two are indeed almost identical (van Ammelrooy 2008), and the minor morphological differences between them could be better explained by ecological reasons. As a consequence the distribution range of X. nasus is enlarged considerably and it is now regarded as being lake-wide (Andersen 2012).
Link to Xenotilapia nasus in the CRC Catalogue.