FAHAY AND MARKLE: GADIFORMES 



279 



transient; larval pigmentation, lateral maxillary fangs, pterotic 

 spines, pedunculate pectoral fin bases, sequence of develop- 

 mental events and the presence of a pelagic juvenile stage. Many 

 of these characters are incompletely known for the order and 

 only tentative phylogenetic statements can be made. 



Embryonic and larval pigmentation patterns are quite vari- 

 able. In gadoids there appears to be widespread occurrence of 

 postanal bands, usually one or two, and melanophores at the 

 notochord tip. Similar patterns occur in Merlnccius bilinearis 

 (Merlucciidae), Physiculus capensis (Moridae) and Coelorhyn- 

 chus sp. (Macrouridae). However, even within one subfamily 

 such as the gadines, there are genera without any banding (e.g., 

 Melanogranuniis) as well as much variation in number of bands 

 (Pollachius. Gadus). Eye pigmentation at hatching varies de- 

 pending on development stage at hatching, for example, unpig- 

 mented in Pollachius and pigmented in Gadus. Embryonic and 

 larval pigmentation seems variable in the well studied gadids 

 as well as in other gadiforms so that an evaluation of phylo- 

 genetic significance seems premature at this time. 



Lateral premaxillary spines are only known in Muraenolepis 

 (Fig. 1 38A) and larval pterotic spines are only known in Phycis, 

 Gaidropsarus (Demir, 1982; Markle, 1982) and Ciliata (Dunn 

 and Matarese, this volume). Both characters appear to be apo- 

 morphies, providing phylogenetic information at the generic 

 level at least. The western Atlantic Phycis. P. chesteri, lacks 

 larval pterotic spines and may, in fact, belong in Urophycis 

 (David Methven, pers. comm.). 



The lack of developmental series outside the gadoids pre- 

 cludes discussion of many developmental sequence characters. 

 However, it does seem possible to make some tentative state- 

 ments about the first fin to form rays. On the basis of our 

 examination of a larval series provided by A. W. North of the 

 British Antarctic Survey, Muraenolepis does not form pelvic 

 rays first. This contrasts with most gadiforms where the pelvic 

 is the first fin to form (Table 74). Other exceptions seem to be 

 in gadines and merlucciids where the caudal or dorsal and anal 

 fins form before the pelvic. The latter condition may represent 

 a derived character state. However, the tail-less macrourids are 

 precluded from showing this character. 



The pectoral fin base is strongly pedunculate (stylopterous) 

 during the larval period in macrourids and steindachneriids, 

 moderately pedunculate in morids and narrow-based (but less 

 pedunculate) in bregmacerotids, Meriuccius and gadids (Fig. 

 143A-D). Strong expression of this character is associated with 

 loss of the caudal fin (macrourids. steindachneriids) or delayed 

 caudal fin formation (morids) and may reflect a compensatory 

 response of larvae associated with larval locomotion. 



In the life history of most gadiforms there is a benthic or 

 engybenthic adult phase. In all of these groups (muraenolepi- 

 dids, morids, most gadids, merlucciids, most macrourids) as 

 well as in pelagic gadiforms there is a prolonged pelagic juvenile 

 stage which, in some cases, includes symbiotic association with 

 jellyfish (Mansueti, 1963). In phycines, for example, this stage 

 is neustonic, includes a pigmentation pattern different from both 

 larval and benthic juveniles, and is characterized by a dense 

 concentration of melanophores on the dorsal surface. In morids, 

 some pelagic juveniles have been described as new genera, such 

 as Svetovidovia Cohen, 1973 (=Gargilius Koefoed, 1953). 



We are not aware of any gadiform that can be shown not to 

 possess a pelagic juvenile. In fact, it appears that life-history 

 neoteny has occurred several times and adults have retained the 

 pelagic habitat (bregmacerotids, melanonids, the gadines Gad- 

 iculus and Micromesistius, and some macrourids). The pelagic 



adult has clearly evolved independently more than once. Even 

 within a single family, Macrouridae, it has apparently happened 

 at least three times and Hubbs and Iwamoto (1977) have called 

 attention to this form of neoteny with the generic name, Me- 

 sobius ("middle life"). 



Pelvic fins.— The gadiform pelvic fin shows two major ontoge- 

 netic sequences. In the phycines, Urophycis and Phycis, larvae 

 initially form 3 or 4 rays and ontogenetically reduce or resorb 

 the innermost ray to produce the adult count of 2 or 3 (Markle, 

 1982). During the course of this study, we have also found 

 ontogenetic pelvic fin ray reduction in the morid Svetovidovia 

 vitellius. One transforming specimen, 55 mm SL (MCZ 59773), 

 has two large pelvic fin rays and 2 or 3 very minute remnants 

 of inner pelvic fin rays. Smaller specimens have as many as 1 1 

 rays (Table 72). Cohen (1979) has previously suggested that 

 Lotella ma.xillaris (10 pelvic fin rays) may be the young of 

 Laemonema (1-3 pelvic fin rays). Gadiforms may be pre-adapt- 

 ed for this type of metamorphosis since even in species with 

 numerous pelvic fin rays, such as the morid Physiculus, the 

 external fin ray nerves appear restricted to the outer two rays 

 (Freihofer, 1970; Fig. 12). 



In the other, presumed ancestral, ontogenetic sequence, pelvic 

 fin rays increase in number. Variation is seen in this sequence 

 in the speed at which the adult complement is formed. The rays 

 form very quickly in Meriuccius, somewhat more slowly in Ele- 

 ginus. and over a protracted size range in Ga/^ropsarw,? (Markle, 

 1982; Dunn and Vinter, 1984, MS). 



In many gadiforms, such as some macrourids, Meriuccius, 

 many gadids and morids, the pelvic fins also change allometri- 

 cally. In the Krohnius and several other types of macrourid 

 larvae as well as in morids, the pelvics are greatly expanded 

 over their relative size in any known adult. In some phycines 

 the pelvics are not necessarily relatively longer, but are wider 

 and fan-like as opposed to filamentous in adults. This allometry 

 favoring a relatively large, fan-like pelvic in the young would 

 seem to be a device to aid flotation. It is noteworthy, however, 

 that only bregmacerotids among the pelagic gadiforms have 

 retained enlarged pelvic fins as adults. 



In addition to elongation, prominent pigmentation of pelvic 

 fins characterizes many genera, including most phycines. The 

 precise extent and location of pigment on the pelvic fin is often 

 an important identifying feature in these larvae. For example, 

 it is absent in Urophycis regia, restricted to the tips of the fins 

 in most other Urophycis and densely covers the fin membrane 

 in U. tenuis, Enchelyopus, Gaidropsarus and Raniceps. 



Gadines, as previously mentioned, show a clear departure in 

 the sequence of fin formation. Instead of forming first, pelvic 

 fins form last. In Meriuccius, whose condition may be an evo- 

 lutionary precursor to the gadine condition, pelvic fins form 

 second in the sequence after the caudal (Table 74). 



Pectoral fins. — \s is the case with most teleosts, pectoral fin rays 

 form late, although they may form before the late-forming cau- 

 dal in morids. As with the pelvic fin, the pectoral fin is often 

 elongate and/or fan-shaped in some morids and macrourids (i.e., 

 Gadella and Hymenocephalus) but this fin is not prominently 

 pigmented in any member of the order except some species of 

 Meriuccius. 



Dorsal and anal fins. — \n the development of all gadiforms de- 

 scribed, vertical fins form in their adult positions and there is 

 no evidence of fin base migration. The dorsal fin origin in gad- 



