. Bulletin of the British Museum (Natural History) Zoology. 152 no LAP G. J. HOWES & AYANOMIYA FUMIHITO ET pal. Fig. 20 Ompok bimaculatus: cranial musculature. Dashed lines indicate underlying DO and A2 muscles. The circular dashed line covering A2 muscle indicates the position of the eye (BMNH :171-8). and shared with other genera of the Siluridae. The mono- phyletic nature of the Siluridae has been shown by Bornbusch (1990) who recognises five synapomorphies. These are the reduced palatine; the occlusion of the frontal margin by the lateral ethmoid and sphenotic; the compressio
. Bulletin of the British Museum (Natural History) Zoology. 152 no LAP G. J. HOWES & AYANOMIYA FUMIHITO ET pal. Fig. 20 Ompok bimaculatus: cranial musculature. Dashed lines indicate underlying DO and A2 muscles. The circular dashed line covering A2 muscle indicates the position of the eye (BMNH :171-8). and shared with other genera of the Siluridae. The mono- phyletic nature of the Siluridae has been shown by Bornbusch (1990) who recognises five synapomorphies. These are the reduced palatine; the occlusion of the frontal margin by the lateral ethmoid and sphenotic; the compression of the transcapular ligament of the posttemporosupracleithrum and the absence of dorsal fin radials and posterodorsally shifted anal fin pterygiophores. In addition to these synapomorphies we recognise a further three, viz; the modification of the frontal sensory canal system (p. 140); the vertical LAP crest on hyomandibular and the longitudinally aligned extensor tentaculi muscle. In addition to these basic silurid synapomorphies Belodontichthys possesses the following derived features with; All Siluridae apart from Silurus: 1. Occipital canals elevated (p. 141) 2. Exoccipital contributes to cranial roof; vagus foramen re- located to posterior face (p. 141) 3. Dorsoanterior process of hyomandibular reduced or absent (p. 145; discussed in Bornbusch, 1988) Exclusively with Silurus, Wallago and Ompok; 4. Raised lateral border of pterotic (p. 140) 5. Muscle A2 aligned vertically to jaw insertion (p. 149) 6. Dilatator operculi originating from the lateral ethmoid (p. 150) 7. Lateral parasphenoid shelf meeting similar ptcrosphenoid shelf (p. 140; see also Character 20) 8. Continuous row of long, recurved inner teeth in both jaws (p. 142) 9. Partially excavated frontals covered posteriorly with epaxial muscle (p. 139) Exclusively with Wallago and Ompok; 139) 10. Upwardly angled vomer and ethmoid (p. 11. Thick, blunt ethmoid cornua (p. 138) 12. Reduced anterior fontanelle (p. 139) 1
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