BRUCE: LARVAL DEVELOPMENT OF BLUE GRENADIER 



Additional 

 Haemal Spine 



Figure 3. — Caudal osteology of a juvenile Macruronus novaezelandiae (181 mm SL). 

 X = X bone, Y = Y bone, EP = epural, SH = superior hypural (hypurals 3 + 4), IH 

 = inferior hypural (hypurals 1 + 21, PH = parhypural, U = ural centra, PU = preural 

 centra. 



form. The pectoral fin in Macruronus larvae is 

 more markedly stalked than in Merluccius. 

 Fahay and Markle ( 1984) suggested that this pec- 

 toral modification in larvae with delayed caudal 

 development may be a compensatory response as- 

 sociated with swimming. 



Although the larvae of the remaining mer- 

 lucciid genera (Lyconus and Lyconodes) are cur- 

 rently unknown, fin structure and position should 

 be useful in separating these from Macruronus. 

 Based on adult features, pelvic insertion should 

 distinguish Macruronus (pelvics inserted behind 

 pectorals) from Lyconus (opposite) and Lyconodes 

 (abdominal). Additionally, Lyconus has only a 

 single dorsal fin and no caudal fin. 



The caudal fin of M. novaezelandiae is similar 

 to Muraenolepis in its confluence with dorsal and 

 anal fins (Fahay and Markle 1984). This similar- 

 ity extends to the undifferentiated X and Y bones 

 and the total caudal fin ray count (12 or 13) re- 

 ported by these authors. However, unlike Mu- 

 raenolepis, M. novaezelandiae has radials fused to 

 the spines of the first preural centrum, which is 

 the more typical gadoid condition. 



Variability in the structure and appearance of 

 bones associated with the caudal fin has been re- 

 ported for other Macruronus species. Marshall 

 ( 1966) observed double neural arches and "super- 

 numary elements" in M. magellanicus. Indeed, 

 variability in gadiform caudal structure ap- 

 pears not to be unusual with examples in several 

 taxa (Markle 1982). Unfortunately, insufficient 

 specimens in the appropriate 35-150 mm size 

 range were available to assess developmental 



characteristics of these variations in blue 

 grenadier. 



ACKNOWLEDGMENTS 



I thank R. Thresher, J. Gunn, J. Leis, and A. 

 Miskiewicz for their reviews of the manuscript. I 

 also thank D. Furlani for sorting the samples and 

 for her considerable patience in the laboratory. 

 This work was supported by a grant from the 

 Fisheries Industry Research Trust Account. 



NOTE: Since the acceptance of this paper, the 

 embryological work by A. Patchell (see section on 

 Development) has been published in New 

 Zealand Journal of Marine and Freshwater Re- 

 search Vol. 21, No. 2. That paper includes a simi- 

 lar larval developmental sequence to that re- 

 ported here. 



LITERATURE CITED 



Ahlstrom. E H , J L Butler, and B Y Sumida 



1976. Pelagic stromateoid fishes (Pisces, Perciformes) of 

 the eastern Pacific: kinds, distributions and early life 

 histories and observations on five of these from the north- 

 west Atlantic. Bull. Mar. Sci. 26:285-402. 

 Badcock, J R . AND N R Merrett 



1976. Midwaterfishes in the eastern North Atlantic. I. 

 Vertical distribution and associated biology in 30° N, 23° 

 W, with developmental notes on certain myctophids. 

 Frog. Oceanogr. 7:3-58. 

 Baker. A C, M R Clarke, and M. J Harrls 



1973. The N.I.O. combination net (RMT 1 + 81 and further 

 developments of rectangular midwatertrawls. J. Mar. 

 Biol. Assn. U.K. 53:167-184. 



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