EARLY DEVELOPMENT OF 

 THE LOPHIID ANGLERFISH, LOPHIUS GASTROPHYSUS 



Yasunobu Matsuura and Nelson Takumi Yoneda 1 



ABSTRACT 



Using larval specimens collected in bongo nets in southern Brazilian waters (between lat. 23° and 29 °S), 

 early development of the lophiid anglerfish, Lophius gastrophysus, is described and compared with other 

 lophiid species. Larval morphology of L. gastrophysus is very similar to that of L. americanus, having 

 three conspicuous melanophores on the trunk and caudal region, but the former can be easily distinguished 

 from the latter by the presence of two melanophores on the preopercular and suborbital regions and 

 positions of the melanophores on the elongate ventral fin. 



The peculiar larvae of Lophius have been known 

 since the description of the early developmental 

 stage of L. americanus by Agassiz (1882). Their 

 characteristic form with elongate dorsal and ven- 

 tral fin rays makes them easily identifiable. Of the 

 25 species of the Lophiidae (Caruso 1981), larvae 

 have been repeatedly described and discussed for 

 L. piscatorius (Prince 1891; Williamson 1911; 

 Stiasny 1911; Allen 1917; Lebour 1919, 1925; Bow- 

 man 1920; Taning 1923; Arbault and Boutin 1968 

 Russel 1976) and for L. americanus (Agassiz 1882 

 Connolly 1920, 1922; Taning 1923; Berrill 1929 

 Dahlgren 1928; Procter et al. 1928; Bigelow and 

 Schroeder 1953; Martin and Drewry 1978; Fahay 

 1983; Pietsch 1984). The larvae of two other species 

 also have been described: L. budegassa (Stiasny 

 1911; Padoa 1956) and L. litulon (Tanaka 1916; Mito 

 1966). There is no literature on larval morphology 

 of L. gastrophysus. 



During ichthyoplankton surveys along the south- 

 ern Brazillian coast, many Lophius larvae were col- 

 lected and identified as L. gastrophysus. This report 

 gives a detailed comparative description of larval 

 development based on 136 specimens collected dur- 

 ing the past 13 years. 



MATERIALS AND METHODS 



Larval specimens used in this report were ob- 

 tained from the collections of ichthyoplankton at the 

 Instituto Oceanografico da Universidade de Sao 

 Paulo. These samples were collected from the south- 

 ern Brazillian coast using a 61 cm bongo net follow- 

 ing the sampling method of Matsuura (1979) and 



preserved in 10% Formalin 2 solution. Notochord 

 length (NL) was taken from the tip of the upper jaw 

 to the tip of the notochord. A total of 136 larvae 

 (3.3-15.7 mm NL) of L. gastrophysus was used in 

 this study. Specimens were measured with a 

 micrometer in a stereoscopic dissecting microscope 

 and illustrations were made with the aid of a camera 

 lucida. 



MORPHOLOGY OF LARVAE 



The smallest identified specimens which were col- 

 lected with plankton nets as free-living forms were 

 about 3.3 mm NL, but they still had a large yolk sac. 

 Fahay (1983) showed that the newly hatched larvae 

 of L. americanus was as small as 2.5 mm long, and 

 they were still encased in the egg veils (Fahay 3 ). The 

 reported size of newly hatched larvae of L. pisca- 

 torius was 4.5 mm TL (Lebour 1925). 



Since the 3.3 mm larvae were not in perfect con- 

 dition, we used larger specimens for the morpho- 

 logical description. Preflexion larvae of L. gastro- 

 physus have a slender body (Fig. 1A, B, C, D), but 

 they later become robust form (Fig. IE, F). This 

 change of body shape is partly a result of increase 

 in body depth and partly due to enlargement of 

 subepidermal space (Fig. 1C, D, E, F), which ap- 

 pears, firstly, on the head region and later becomes 

 larger and extends posteriorly, giving the larvae a 

 balloonlike appearance. This subepidermal space 

 consists of transparent, gelatinous connective tissue 

 and is considered an adaptation to planktonic life 



'Instituto Oceanografico da Universidade de Sao Paulo, Butanta, 

 Sao Paulo 05508, Brasil. 



2 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



3 M. P. Fahay, Northeast Fisheries Center Sandy Hook Labora- 

 tory, National Marine Fisheries Service, NOAA, Highlands, NJ 

 07732, pers. commun. July 1985. 



Manuscript accepted August 1985. 



FISHERY BULLETIN: VOL. 84, NO. 2, 1986. 



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