The members of the genus Synodontis, commonly known as the squeaker catfishes of Lake Tanganyika, evolved from a single common ancestor according to a paper* published in a recent issue of the Journal of Evolutionary Biology.

synodontis catfish

Researchers Day, Bills and Friel** analysed 1697 base-pair sequences consisting of nuclear (ribosomal protein-codin gene S7), mitochondrial (cytochrome b) and transfer RNA gene fragments in 65 samples (representing about 40 species) of squeaker catfishes to study the evolutionary relationships of the group.

Through their research, the authors were able to track down a single origin for the Lake Tanganyika species flock. The members of the genus Synodontis all evolved within the last 5.5 million years which makes them a comparatively new addition to this Great Rift Valley Lake which is believed to be at least 9 million, perhaps even 12 million, years old.

Day, Bills and Friel also recovered a monophyletic group of southern African riverine species which seems to have diversified very rapidly (during the last 890,000 years). This group was believed to have been formed due to adaptive radiation within Lake Makgadikgadi; a lake which is now extinct.

* Day, JJ, R Bills & JP Friel (2009) Lacustrine radiations in African Synodontis catfish. Journal of Evolutionary Biology 22, pp. 805–817.

**Julia Day, Roger Bills and John Friel

New species of catfish from the Ngounié River

Belgian and French scientist[1] have now described and named an African catfish sporting a striking pattern of irregular whitish lines and dots over a black background. The fish has been given the name Synodontis ngouniensis after its type locality, the Ngounié River drainage. The Ngounie River is the last and second most important tributary of the famous Ogowe River and flows through the country Gabon in west central Africa. The species can also be found in the Nyanga River drainage in Congo. (Nyanga is a smaller coastal river that runs through southern Gabon and northern Congo.)

The researchers collected Synodontis ngouniensis from a turbid part of the Ngounié River, where the temperature was 24°C (roughly 75°F) and the pH-value 8.4 (very alkaline).

Synodontis ngouniensis is a mochokid catfish. Its dorsal spine has a smooth anterior margin except for 1-4 feeble serrations that can be seen on the distal part. The species also has a maxillary barbel with a smooth membrane which is proximally at least as broad as the barbel thread and located on the posterior basal two third of the barbel. The fish is equipped with 12-19 mandibular teeth, 10-13 gill rakers on the ceratobranchial of the first branchial arch, and a triangular humeral process.

If you want to learn more, you can find the description of the fish in Ichthyological Exploration of Freshwaters 19[2].

New species of catfish from the Woleu River

This new species of mochokid catfish has long been confused with another similar species, Synodontis batesii, but has now been recognized as a species in its own right thanks to the work of researchers John Friel and John Sullivan. The new species has been given the name Synodontis woleuensis after the river Woleu and has is known to be present in the Woleu/Mbini/Uoro and Ntem basins of Gabon and Equatorial Guinea in west central Africa.

Synodontis woleuensis sports a dark background colour decorated with numerous small light spots of irregular shapes. A pair of light spots can be seen anterior and posterior to the adipose fin, and a narrow depigmented curved band runs along the anterior margin of the caudal fin. Another notable feature is the serrations on the anterior edge of the dorsal spine of the fish. 

If you wish to learn more about this new species, you can find the description in the latest issue of Proceedings of the Academy of Natural Sciences of Philadelphia[3].