. Bulletin of the British Museum (Natural History) Zoology. 158 G. J. HOWES & AYANOMIYA FUMIHITO. Fig. 27 Cladogram of Siluridae constructed from the synapomorphies discussed in the text (p. 00). Monophyly of the Siluridae follows Bornbusch (1990) with the addition of three other synapomorphies (1-3) involving frontal sensory canals, hyomandibular crest and extensor tenatculi muscle (p. 00). Characters 1-3 are absent in Silurus (see Discussion). The 'other Siluridae' lineage comprises Hemisilurus, Ceratoglanis, Kryptopterus, Silurichthys and Ompok sensu lato (see text). infraorbital sensor
. Bulletin of the British Museum (Natural History) Zoology. 158 G. J. HOWES & AYANOMIYA FUMIHITO. Fig. 27 Cladogram of Siluridae constructed from the synapomorphies discussed in the text (p. 00). Monophyly of the Siluridae follows Bornbusch (1990) with the addition of three other synapomorphies (1-3) involving frontal sensory canals, hyomandibular crest and extensor tenatculi muscle (p. 00). Characters 1-3 are absent in Silurus (see Discussion). The 'other Siluridae' lineage comprises Hemisilurus, Ceratoglanis, Kryptopterus, Silurichthys and Ompok sensu lato (see text). infraorbital sensory canals. According to Lundberg (1982) the anterior displacement of the temporal canal branching point into the frontal is the result of jaw muscle insertion on to the cranium. In the Siluridae the development of the lateral branch of the frontal canal was also possibly initiated by encroachment of muscle onto the cranium, in this case, however, epaxial rather than jaw adductor muscle. The sequence of phylogenetic changes culminating in the derived condition of the Belodontichthys cranium are evident in the successively derived sister-taxa Wallago and Ompok in which the lateral branch of the frontal sensory canal occurs transversely in the former and backwardly curved in the latter, with correlated anterior shifts of the cross-commissure, truncation of the anterior fontanel and posterior lengthening of the frontal crest. Concomitant with these changes in frontal topography is the forward encroachment with epaxial musculature on to the bone. In no other teleost known to us has the forward extension of the epaxial musculature produced such a profound modification to the frontals. Among otophysans only two cyprinids Macrochirichthys and Pelecus display similar modifications. In both these taxa the frontals are concave but principally in the transverse and only slightly in the axial plane; in neither is there a median frontal crest. In both taxa the epaxial muscle extends to the an
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