30 



G.J. HOWES 



laterally (Howes, 1988; 1991b). 



Melanonids have a small intercalar, a bone which in other 

 gadiforms contributes to a substantial part of the lateroposte- 

 rior cranial wall. In size the melanonid intercalar approaches 

 that of Percopsis. Whether in Melanonus the bone is plesio- 

 morphically small or whether there has been reduction sec- 

 ondarily can only be assessed against the distribution of 

 other, known derived features (Fig. 18). An intercalar is 

 absent in lophiiforms and batrachoidiforms, an assumed 

 secondary loss (Patterson & Rosen, 1989). 



The single dorsal fin is probably a plesiomorphic feature 

 (p. 26). Among paracanthopterygians, an elongate second 

 dorsal fin is assumed to be synapomorphic for anacanthines 

 (sensu Patterson & Rosen, 1989). Melanonids share with 

 ophidiiforms (including carapids and bythitoids), two gadoid 

 genera (Lyconus and Brosme) and Macrouroididae a single 

 dorsal fin which must be seen as resulting from either the 

 'loss' of the first dorsal with anterior encroachment of the 

 second, or the amalgamation of the two fins. It is impossible 

 to distinguish between such phylogenetic events although 

 either way the condition is seen as derived. Iwamoto (1989) 

 considered the single dorsal fin of macrouroidids to be 

 derived but that of the gadoid Brosme as plesiomorphic 

 retention. Judging by the incongruent distribution of the 

 character it is almost certainly homoplastic. The further 

 partitioning into three fins in Gadidae represents a further 

 derived state. 



In jaw musculature melanonids are little different from 

 morids and bathygadids (Howes, 1988). Howes (1990; 1991b) 

 noted a medial shift of adductor muscle Alb which would 

 suggest a close phylogenetic relationship with supragadoids. 

 This shift, however, is apparently induced by the presence of 

 a unique transverse ligament which runs from the palatine to 

 the inner face of the second infraorbital and which constricts 

 and turns Alb inwards. This is not the same condition as the 

 entire medial shift of an unconstricted Alb in 'supragadoids'. 



Melanonids have an unusual condition of the hyoid muscu- 

 lature whereby the pharyngohyoideus (= rectus communis) 

 attaches to the third hypobranchial as well as the urohyal 

 (Howes, 1988). Urohyal attachment of the pharyngohyoideus 

 is shared with macrouroids, two gadoid families and all other 

 ctenosquamates (Lauder, 1983; Howes, 1988); in remaining 

 gadoids the pharyngohyoideus is mediated by the sternohyoi- 

 deus. It is assumed that the two exceptional gadoid families 

 (Muraenolepididae and Ranicipitidae) have lost the sternohy- 

 oideus attachment, the pharyngohyoideus being attached to 

 the tip rather than the lateral face of the urohyal keel as it is 

 plesiomorphically in melanonids. 



The melanonid caudal fin musculature (p. 26) lacks those 

 features regarded as synapomorphic for gadoids (since mac- 

 rouroids lack caudal fin skeletons and associated musculature 

 it cannot be known whether this derived form of muscle 

 arrangement was a gadiform feature subsequently lost in 

 macrouroids). Melanonids have a caudal fin muscle arrange- 

 ment only slightly modified from that present in other para- 

 canthopterygians and in acanthopterygians. 



Although it cannot be doubted that the Melanonidae 

 belongs among Gadiformes there is no evidence to suggest 

 that it be regarded as a member of the Gadoidei. To be 

 included within the Gadoidei, the elongate toothed palatine, 

 lack of X and Y bones, reduced intercalar and single dorsal 

 fin must be regarded as reversal and loss characters. The 

 caudal fin skeleton demonstrates an advanced condition to 

 that of the Moridae (the plesiomorphic gadoid taxon) in 



having, in adults, almost complete fusion of the upper 

 hypurals which alone, would signify inclusion within the 

 'supragadoids'. Indeed, I have argued elsewhere (Howes, 

 1991b: caption to fig. 35) that the reported separation of 

 hypurals in young ranicipitids (which I place amongst the 

 'supragadoids') is a character reversal; a conclusion drawn on 

 what appears to substantial support from other synapomor- 

 phies. In the case of melanonids the principal evidence 

 against the caudal fin skeleton being a character reversal is 

 that the associated musculature has a plesiomorphic arrange- 

 ment, lacking those derived elements found in the muscula- 

 ture of morids and other gadoids, including ranicipitids (as an 

 adult, Raniceps has the typically symmetrical gadoid caudal 

 fin skeleton, lacking in Melanonus). Thus the fusion or partial 

 fusion of the upper hypurals in melanonids is considered to 

 have occurred independently to that in gadoids above the 

 morid level. 



Taking into account these arguments and the anatomical 

 evidence presented herein, the Melanonidae is regarded a 

 basal gadiform taxon, representing, as Markle (1989) had 

 previously hypothesised, the sister-group to both gadoids and 

 macrouroids (Fig. 18). Such a phylogenetic arrangement 

 leads to a higher level re-classification of the Melanonidae. 

 Following Markle (1989) and recognising the family as being 

 phylogenetically coordinate with the Macrouroidei and 

 Gadoidei, it is placed in the suborder Melanonoidei. Those 

 taxa which I have previously recognised as a monophyletic 

 group termed 'supragadoids' are equivalent to Markle's 

 (1989) Superfamily Gadoidea. The Moridae and Euclichthy- 

 idae are regarded by Markle (1989) as sister taxa on the basis 

 of asymmetry of procurrent caudal fin rays; I know of no 

 supporting osteological synapomorphies for this relationship 

 but provisionally accept it. Together these taxa form the 

 sister-group to the Gadoidea and as such must be regarded as 

 the Superfamily Moridoidea (= Moriformes, 



part,Schwarzhans, 1984). The 'infragadoids', Steindachneri- 

 idae and Bathygadidae have no such status since they form an 

 unresolved polychotomy with the Gadoidei + Moroidei and 

 Macrouroidei. 



Acknowledgements. My thanks are due to Douglas Markle, Nigel 

 Merrett and Colin Patterson for their helpful and critical comments 

 on the manuscript of this paper. Since this is the final research project 

 carried out while employed at The Natural History Museum I take 

 this opportunity to thank all members of staff, associates and 

 students past and present of the Fish Section for their advice, 

 assistance, patience, generosity and friendship over the past twenty- 

 five years. I am particularly indebted to my mentors, P. Humphry 

 Greenwood and Ethelwynn Trewavas. 



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Fahay, M. P. 1989. The ontogeny of Sleindachneria argentea Goode & Bean, 

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