ANATOMY OF THE MELANONIDAE 



23 



branchial arch of Melanonus which he considers, due to the 

 presence of a large and chondrified interarcual ligament, to 

 be plesiomorphic for gadiforms. In his cladogram, however, 

 he mistakenly ascribes to Melanonus the loss of the second 

 pharyngobranchial. The lower gill-arch is also plesiomorphic 

 in that the basibranchials are unexpanded and there is no 

 forward ventral elongation of the third hypobranchial as in 

 macrouroids and ophidiiforms; the first hypobranchial is 

 typically long as in gadiforms but lacks an expansion where 

 the ligament running to the dorsohyal attaches. Spinous 

 gill-rakers of both the clustered- and triple-spine type are 

 widespread amongst 'infragadoids' and macrouroids. 



Pectoral girdle (Fig. 12) 



The vertical and horizontal limbs of the cleithrum (Fig. 12A) 

 are nearly equal in length; the medial cleithral lamina is thin 

 and only prominent near the cleithral tip. Markle (1989) 

 noted that the foramen which notches medial borders of both 

 the scapula and coracoid is present only in the former 

 (Fig. 12A). Markle (1989) and Howes & Crimmen (1990) 

 commented on the variability of this feature; plesiomorphi- 

 cally the foramen lies entirely within the scapula, a condition 



almost entirely confined to 'infragadoids' although it is also 

 recorded in the 'supragadoid' Lota. The supracleithrum 

 (Fig. 12B) is a lanceolate bone with a slightly expanded 

 dorsal articulatory surface which contacts the posttemporal. 

 There are four actinosts and 12 or 13 pectoral rays in the M. 

 zugmayeri specimens examined (Norman, 1930, gives 13 for 

 M.zugmayeri and 12-14 for M. gracilis; Fahay & Markle, 

 1984, give a range for the genus of 10-16). The single 

 postcleithrum (Fig. 12A) has a broad head and slender, 

 slightly upwardly curved stem. It articulates in a cleft oppo- 

 site or slightly above the coracoid-scapula junction (see also 

 Markle, 1989, fig. 10). 



The posttemporal (Fig. 12B) is V-shaped, its upper limb 

 broad proximally and tapering distally; its lower limb, which 

 is firmly united with the intercalar is thin, rod-like and 

 completely ossified. 



The extrascapulars (Figs 4A, 5A,B, 6C) number four, each 

 having upturned borders and containing a neuromast. The 

 lateral extrascapular covers the posterior corner of the 

 pterotic, two lie in contact with one another along the medial 

 part of that bone and the innermost lies along the lateral part 

 of the parietal. In large specimens of M. zugmayeri the 



ac 



wt 



Fig. 12. Melanonus zugmayeri: A, pectoral girdle in medial view; B, posttemporal and supracleithrum in lateral views; C, pelvic girdle in 

 dorsal view. 



