COHEN: GADIFORMES 



265 



Family Merlucciidae 

 Subfamily Merlucciinae (including "Protocodus," Rhi- 

 nocephalus. Palaeogadus, Merluccius. Macruronus, 

 and Lyconus) 

 Subfamily Steindachneriinae 

 Family Gadidae 

 Family Lotidae 



Family Phycidae 

 Family Moridae 

 Family Melanonidae 



Life Sciences Division. Los Angeles County Museum of 

 Natural History, 900 Exposition Boulevard, Los 

 Angeles, California 90007. 



Gadiformes: Development and Relationships 

 M. P. Fahay and D. F. Markle 



AS treated herein, the Gadiformes includes about 63 genera 

 and 400+ species (Nelson, 1976) divided into eight fam- 

 ilies (Gosline, 1968; Marshall and Cohen, 1973); (but see Cohen, 

 this volume). They are primarily marine with familial distri- 

 bution "centers" as follows: Muraenolepididae— high latitudes, 

 southern hemisphere; Bregmacerotidae — tropical and sub- 

 tropical, world-wide; Melanonidae— tropical and sub-tropical, 

 world-wide; Moridae— world-wide; Macrouridae— deep sea, 

 world-wide; Steindachneriidae— tropical W. Atlantic; Merlucci- 

 idae— mid-latitudes, both hemispheres; and Gadidae— high lat- 

 itudes, northern hemisphere with minor freshwater and south- 

 em hemisphere components. 



Meristic characters of genera within each family are presented 

 in Table 72 (except that macrourid characters will be found in 

 Table 75). Gadiforms characteristically have relatively high ver- 

 tebral counts, with caudal centra outnumbering precaudal cen- 

 tra, usually by a wide margin. The first two centra lack ribs and 

 parapophyses. Vertical fins have numerous rays and long bases, 

 with posterior dorsal and anal rays separate from caudal fin rays 

 except in Miiraenolepis and macruronines. Pectoral fins are typ- 

 ically high on the body and pelvic fins typically thoracic or 

 jugular in position. Mental barbels are found in many genera 

 and mouth position ranges from terminal to inferior. 



Present State of KnowLedge and 



Characters of Early Life 



History Stages 



Literature on gadiform eggs and larvae is heavily weighted 

 towards gadids and merlucciids. within which the commercially 

 important gadines and Merluccius have received most attention. 

 Gadine larvae were among the first marine fish larvae to be 

 described. In fact. G. O. Sar's discovery, early in the 1860's, 

 that cod eggs and larvae were pelagic, helped initiate fisheries- 

 oriented ichthyoplankton surveys. In addition to their com- 

 mercial importance, gadines and Merluccius are found in shelf 

 waters where their early stages are more accessible than those 

 of other gadiforms which are largely residents of slope and oceanic 

 waters. 



Published descriptions of gadiform early life history stages 

 are listed in Table 73. We especially note the seminal work on 

 young gadids done by Johannes Schmidt in the early 1900's. 

 Although he stressed pigment patterns over other develop- 



mental features. Schmidt was one of the first to look at several 

 species in a systematic fashion. 



In the following review, we summarize gadiform characters 

 in brief family synopses as well as through a limited survey of 

 the ontogeny of selected characters. Our purposes are, respec- 

 tively, to point out what appear to be easily observed diagnostic 

 early life history characters and to contribute to discussions of 

 gadiform phylogeny. 



Gadiformes.— The gut of gadiform larvae coils early in ontogeny 

 and combined with a tapering postanal region and rounded 

 head, contributes to an overall tadpole-like appearance. These 

 features are, in part, a reflection of vertebral and vertical fin ray 

 elements (Table 72) and are not diagnostic. Although it has not 

 been documented in all families and is not always easily ob- 

 served, yolk-sac and first-feeding gadiform larvae have an anus 

 that exits laterally through the finfold rather than medially as 

 is usual in teleost larvae. Some secondary caudal rays develop 

 before some primary in forms with a caudal fin. 



In Table 74 we summarize some developmental features of 

 each family. A rather widespread trend is for the pelvic fin to 

 be the earliest forming fin. There does not seem to be any char- 

 acter unique or diagnostic for young gadiforms. The features of 

 body shape, anus morphology and pelvic fin development in 

 combination with specific familial characters appear to be the 

 most useful for initial identification. Transformation is gradual 

 and direct with no striking changes in ontogeny. 



Muraenolepididae. — \ single planktonic juvenile (see discus- 

 sion of planktonic juveniles below) of Muraenolepis sp. is shown 

 in Fig. 138 A. The distinctive first dorsal fin, composed of one 

 or two rays, the confluent vertical fins, meristic characters (Ta- 

 bles 72 and 76), chin barbel, restricted gill opening and capture 

 locality (53°48.7'S, 38°18.7'W) preclude all other teleosts and 

 agree with characters described for Muraenolepis (Svetovidov, 

 1948). The lateral premaxillary spines (Fig. 138A) were not 

 shown in a schematic illustration of an early Muraenolepis (North 

 and White. 1982) or in larvae described by Efremenko (1983b) 

 and are not reported for adults. It is possible that they are not 

 found in larvae of all species of Muraenolepis, but for present 

 purposes we consider them a unique and diagnostic larval spe- 

 cialization of the family. 



