Xenocharax is a characin or tetra, a member of the order Characiformes. Characins, along with minnows, carps, catfishes and knifefishes, belong to the clade Otophysi. Otophysans make up nearly 75% of the freshwater fishes of the world, comprising more than 10,000 named taxa. The 1500+ characin species are divided into a large number of families (typically 14-16) with most of the representation in the Neotropics, but 200+ species (2-4 families) occur in Africa.
The higher-level classification of characins is notoriously unstable, with no complete phylogeny published in recent years. Most workers place the African families throughout the order, suggesting that characins began to diversify prior to the split between Africa and South America during the Cretaceous. Xenocharax is a member of the family (or sometimes subfamily) Distichodontidae, a basal clade of Characiformes. The images and animations here provide good anatomical detail for understanding morphological evolution within the order.
About the Species
This specimen was collected in the Lékoli River, Odzala National Park, Republic of Congo by J. P. Friel and S. Lavoué on 10 August 2002. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning courtesy of Dr. Julian Humphries of The University of Texas at Austin. Funding for scanning and image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.
Lateral view of the scanned specimen.
About this Specimen
The specimen was scanned by Matthew Colbert on 24 June 2003 along the coronal axis for a total of 960 slices. Each 1024x1024 pixel slice is 0.134 mm thick, with an interslice spacing of 0.134 mm and a field of reconstruction of 63.0 mm.