. Bulletin of the British Museum (Natural History) Zoology. . Fig. 11 Insertion of adductor mandibulae muscle to upper jaw in: a. Onychostoma sima b. Scaphiodonichthys burmanicus c. Cyprinion macrostomus d. Varicorhinus beso to be the plesiomorphic condition. Only Scaphiodonichthys and Schizothorax (Fig. 13k,1) share the supposedly derived infraorbital morphology of Onychostoma and Scaphesthes. Vertebral column and dorsal fin In Onychostoma sima (Fig. 14a) the neural complex is tall and axe-shaped with a forwardly inclined anterior border and widely separated from the supraoccipital as in most
. Bulletin of the British Museum (Natural History) Zoology. . Fig. 11 Insertion of adductor mandibulae muscle to upper jaw in: a. Onychostoma sima b. Scaphiodonichthys burmanicus c. Cyprinion macrostomus d. Varicorhinus beso to be the plesiomorphic condition. Only Scaphiodonichthys and Schizothorax (Fig. 13k,1) share the supposedly derived infraorbital morphology of Onychostoma and Scaphesthes. Vertebral column and dorsal fin In Onychostoma sima (Fig. 14a) the neural complex is tall and axe-shaped with a forwardly inclined anterior border and widely separated from the supraoccipital as in most barbins. The posterior border of the neural complex is slightly concave and widely separated from the posteriorly inclined 4th neural spine, which is less than a half its height. There are 7 supraneurals between the neural complex and the first dorsal pterygiophore. Each supraneural is a lamellar, triangular, poorly ossified bone narrowly separated from each of those adjacent, their dorsal borders forming an almost continuous bony ridge along the midline of the body. The anterior neural spines are tall and slender. In Scaphesthes barbatulus (Fig. 14b) the neural complex is low with irregular anterior and posterior borders. The 4th neural spine is short and widely separated from the posterior border of the neural complex. There are 8 stick-like supra- neurals of irregular size between the neural complex and the first dorsal pterygiophore. These two morphotypes of the vertebral column are present in species of Onychostoma, Scaphesthes and Cyprinion. That described for O. sima is also found in O. gerlachi, O. rhomboides, S. lepturus, C. macrostomus and C. watsoni; that for S. barbatus is also found in S. macrolepis and O. lini. Howes (1982) described the anterior vertebral column of Semiplotus semiplotus and Scaphiodonichthys burmanicus. In the former, the supraneurals are enlarged, articulating with each other and overlapping the neural complex and the first dorsal pterygiophore
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