CASTLE: NOTACANTHIFORMES, ANGUILLIFORMES 



63 



Leptocephalus giganteus 390mm TL 



'Tilurus" 



"Tiluropsis' 



Fig. 29. The three major forms of notacanth leptocephali showing in upper two the elongate snout, distinct dorsal (arrow), and ventral 

 melanophore series; in lower left the myoseptal pigment; and in lower right the oval eye. 



superfamily Saccopharyngoidea (gulpers), a small group of 3 

 families, 4 genera and 8 species of highly modified mid-water, 

 oceanic eels, unmistakeable in body form and possessing a lep- 

 tocephalus of distinctive type. Although they are currently ac- 

 cepted to be true eels, they are so highly aberrant in form and 

 osteology that a case could be made for their retention in a 

 separate suborder, as indeed was proposed by Greenwood et al. 

 (1966). Other eel families have been studied in some detail, 

 notably the Congridae (Smith. 1971), Synaphobranchoidea 

 (Robins and Robins, 1976), Ophichthidae (McCosker, 1977), 

 Nemichthyidae (Nielsen and Smith, 1978) and others, but there 

 are several major gaps and the order has never been compre- 

 hensively reviewed. 



With some exceptions, the families and genera of eels occur 

 worldwide (Table 9) while eel species have a more restricted 

 distribution in one or other of the major oceans. Some meso- 

 pelagic, slope/abyssal species and just a few shelf species are 



known from both Indo-west Pacific and Atlantic. As for many 

 other teleosts. the Indo-west Pacific is richest in genera and 

 species, despite relatively limited collecting there, and infor- 

 mation is scattered (Alcock. 1889 e/.yf(7!/.: Fowler, 1934;Asano, 

 1962; Karrer, 1982). The eel fauna of the Atlantic is rather better 

 known (Blache, 1977; Bohlke, 1978) but by comparison the 

 group is rather poorly represented in the East Pacific. 



Characters.— The families and genera of Anguilliformes are dis- 

 tinguished principally by external characters, including mor- 

 phometries (Table 10) but the limits are not yet firmly estab- 

 lished for all families in the order. Osteological characters, which 

 mostly reflect these external modifications are also of value at 

 family and generic levels (Table 1 1 ) but are inadequately known, 

 especially in the Congridae and related families, and the Mu- 

 raenidae. Too few genera have been identified in their larval 

 form for ontogenetic characters to have been used extensively 



