ANATOMY OF THE MELANONIDAE 



29 



MELANONOIDEI MACROUROIDEI 



GADOIDEI 



^Bathygadidae Steindachneriidae Moridoidea Gadoidea] 



12. 13 



10:11 



Fig. 18. Proposed relationships of Melanonoidei with other gadiforms. Synapomorphies: 1, absence of pars jugularis, i.e. common aperture 

 for principal cranial nerves (also occurs in some ophidiiforms); 2, loss of intermusculars from vertebrae 1 and 2; 3, scapular-coracoid 

 foramen; 4, attrition of lateral face of hyomandibular; 5, levator arcus palatini covers lateral face of jaw musculature; 10, palatine forming a 

 hinge or butt-joint with pterygoids; 11, enlarged intercalar contributing to posterior wall of cranium; 12, pharyngohyoideus muscle mediated 

 by sternohyoideus; 13, interradiales muscle connected to dorsal and anal fin rays, loss of various caudal fin muscles and entire caudal skeleton 

 in some taxa; 14, palatine contacts mesethmoid; 15, X and Y bones in caudal skeleton (lost in some laxa); 16, complete fusion of upper 

 hypurals and symmetry of hypural plates. Autapomorphies for Melanonoidei; 6, supraoccipital excluded from margin of foramen magnum; 7, 

 cranial neuromas! pattern and innervation; 8, brain position and morphology; 9, enlarged pterosphenoids contacting lateral ethmoids. 

 Synapomorphies 1-5 and 10-11 from Gosline (1968; 1971); Howes (1988; 1989; 1990; 1991b); Markle (1989); Patterson & Rosen (1989). 

 Synapomorphies for macrouroids summarized by Iwamoto (1989) and Howes & Crimmen (1990) and for moridoids by Paulin (1983). 



taxa so excluded are Moridae, Euclichthyidae, Steindachneri- 

 idae and Bathygadidae. The two latter lack a caudal fin 

 skeleton, thus the incomplete fusion patterns of hypural bones 

 possessed by morids, euclichthyids and melanonids cannot be 

 extended to these taxa. The cranial and vertebral osteology of 

 Bathygadidae is plesiomorphic in comparison to other gadoid 

 taxa whereas that of Steindachneriidae is relatively derived 

 (pers. obs. see also Fahay's, 1989, notes on pelvic girdle 

 morphology). 



The Melanonidae lacks a feature common to other 

 gadiforms (macrouroids + gadoids), namely, a short palatine 

 forming a butt or hinge joint with the ento- and ectopterygo- 

 ids. In almost all gadiforms the palatine has a truncated near 

 vertical margin which forms a mobile (laterally expanding) 

 joint with the anterior margins of the pterygoid bones (p. 20). 

 Melanonus has a plesiomorphic palatine where the stem 

 firmly contacts the margin of the ectopterygoid. Moreover, 

 the palatine extends some distance along the ectopterygoid 

 and is toothed. Since no other gadiform has palatine teeth it 

 might be assumed that the melanonid palatine is the primi- 

 tively composite dermo- and autopalatine whereas other 

 gadiforms have lost the dermal component. In other paracan- 

 thopterygians, ophidiiforms and lophiiforms possess the ple- 

 siomorphic, long posteriorly extended and toothed palatine; 



percopsids resemble gadiforms more closely in having an 

 edentulous bone which abuts the straight anterior margins of 

 the ecto- and entopterygoids but which still retains a posteri- 

 orly directed stem (p. 20). 



The Melanonidae possesses three of those characters iden- 

 tified by Patterson & Rosen (1989) and Markle (1989) as 

 gadiform synapomorphies or potential synapomorphies, 

 namely, absence of epipleural ribs from the first and second 

 vertebrae; a scapular-coracoid foramen and absence of a 

 lateral commissure, cranial nerves I— VII exiting through a 

 common aperture. Two other potential synapomorphies 

 listed by Patterson & Rosen (1989) are presence of X and Y 

 bones and liver LDH pattern. X and Y bones are absent in 

 melanonids and can only be judged as a plesiomorphic state 

 or, against the congruence of other synapomorphies, as 

 secondary loss. In the latter case the feature then appears as 

 synapomorphic for a subgroup of gadoids (Fig. 18). LDH 

 liver pattern has not been tested for in this taxon. 



Two other synapomorphies appear to be: 1) the form of the 

 hyomandibular, which in the majority of gadoids and mac- 

 rouroids has attrition of the anterior border and lateral face, 

 fully or partly exposing the pathway of the hyoid branch of 

 the facial nerve (Howes, 1989; 1991b; 1992); 2) the levator 

 arcus palatini covering the adductor mandibulae musculature 



