A taxonomic revision of Parachela with descriptions of two new species (Cypriniformes: Xenocyprididae).

The taxonomy of the Parachela-Oxygaster-Macrochirichthys clade of Xenocyprididae has been confused since the original descriptions of Parachela oxygastroides and Parachela hypophthalmus in the mid-19th century. The confusion seems attributable to the substantial intraspecific variation in color and other morphological characteristics of species of Oxygaster and Parachela. Morphological data on 401 specimens from throughout the range of Parachela and molecular phylogenetic analyses indicate that six available species names for Parachela are valid: Parachela cyanea, P. hypophthalmus, Parachela ingerkongi, Parachela johorensis (removed from the synonymy of P. oxygastroides), P. oxygastroides, and Parachela williaminae. In addition, two new species of Parachela, Parachela melanosticta and Parachela microlepis, are described. Chela pointoni is a synonym of P. oxygastroides, not a valid species of Oxygaster as previously hypothesized, and Parachela maculicauda is a synonym of Parachela johorensis. Considerable morphological and genetic variation is present in all well-sampled species of Parachela.