22 



G.J. HOWES 



Fig. 10. Melanonus zugmayeri hyoid bar of 100mm SL specimen: 

 A, medial view; B and C, urohyal in lateral and dorsal views. 



one not shared by ophidiiforms or lophiiforms (Howes, 

 1992). 



Other hyoid arch bones are much like those of the majority 

 of gadiforms; the posterior half of the anterohyal =ceratohyal 

 auct. (Figs 10A, 11 A) is deep and in this respect resembles 

 that bone in some macrouroids (eg. Nezumia, Abyssicola, 

 Coelorhynchus, Coryphaenoides; Okamura, 1970), more 

 closely than gadoids. However, this feature is variable and a 

 similar range of morphotypes can be found among ophidii- 

 forms (Markle & Olney, 1990, fig. 13). As in most gadiforms 

 and ophidiiforms there are 7 branchiostegal rays which 

 appears to be the plesiomorphic paracanthopterygian num- 

 ber, (six occur frequently in lophiiforms). The urohyal 

 (Figs 10B,C) bears a closer resemblance to that of gadoids 

 rather than macrouroids in having a shallow dorsal keel and a 

 long, prominent anterodorsal (basibranchial) process 

 (Howes, 1990, fig. 16B). 



The basihyal (Fig. 11 A) is a dumbbell-shaped bone lying 

 between the dorsohyals and crossed by a ligament which 

 connects them; anteriorly a thick cartilaginous 'tongue' pro- 

 trudes forward, posteriorly, the basihyal is slightly over- 

 lapped by the first basibranchial(see below). The interhyal 

 (Fig. 9A) is typically gadiform, being long and slender, 

 contacting the symplectic cartilage dorsally and the posterior 

 socket of the posterohyal ventrally. Markle (1989, fig. 6A) 

 shows a common ligamentous connection between the 

 interhyal-posterohyal and interopercle. I find this to be one 

 involving thick connective tissue although a discrete ligament 

 runs from the medial side of the interhyal to the medial 

 posterior tip of the posterohyal. 



Opercular bones (Fig. 9A) 



The opercular bones are relatively generalised except that the 

 suboperculum has a straight to concave leading edge rather 

 than the common gadiform condition of a rounded to pointed 

 margin. The interopercle is shallow and nearly oblong with 

 rounded dorsoposterior and anteroventral borders; it is 

 widely separated from, and ligamentously connected to the 

 subopercle. In general, macrouroids have the interopercle 

 orientated horizontally (e.g. Okamura, 1970, figs 26; 27) 

 whereas in gadoids the bone is angled, sometimes steeply as 

 in Melanonus. Melanonus lacks the interopercular fossa 

 present in a subgroup of 'supragadoids' (Howes, 1990). The 

 opercle is relatively large for a gadiform and overlaps most of 

 the subopercle. The preopercle has a short lower, anteriorly 

 directed limb and a narrow laminate (symplectic) process 



which, plesiomorphically, contacts the symplectic cartilage. 

 In its derived form the symplectic process of the preopercle 

 contacts the lateral face of the hyomandibular (Howes, 1990). 



Branchial arches (Fig. 11) 



There are three basibranchials (Fig. 11 A), the first and 

 second ossified, the third cartilaginous. The posterior margin 

 of the first overlies the the anterior border of the diamond- 

 shaped second which is separated from the small diamond- 

 shaped third. The first and second hypobranchials (Fig. 11 A) 

 are long with marked posterior curvature, both contacting the 

 first basibranchial and bear gill-rakers on their outer and 

 inner margins; the third is short and lacks gill-rakers. The first 

 and second ceratobranchials (Fig. 11 A) bear five or six 

 clustered-spinous rakers on their outer and the same number 

 of slender, triple-spine rakers on their inner margins; the 

 third has seven outer and inner shorter rakers and the fourth 

 has four short rakers on its outer margin only. The anterior 

 tips of the fifth ceratobranchials are apposed but not firmly 

 united in the midline and are ligamentously connected to the 

 third basibranchial; a narrow tooth patch bears ca 25 slender 

 pointed teeth. 



The epibranchials (Fig. 11B) are 30% the length of the 

 ceratobranchials. A strong uncinate process on the first 

 epibranchial is connected by a chondrified ligament to a large 

 interarcual cartilage; the third epibranchial bears a long tooth 

 plate bearing ca 20 sharp pointed teeth. There are four 

 pharyngobranchials (Fig. 11B), the first being an ossified 

 element; the second-third pharyngobranchial tooth plates 

 bear strong, pointed teeth. 



Markle (1989) has described and commented on the upper 



bM-3 



pbb1-3 



Fig. 11. Melanonus zugmayeri branchial arches of 130mm SL 

 specimen: A, dorsal view of lower arch elements; B, ventral view 

 of upper arch elements. In A, basihyal is also shown in lateral 

 view. 



