LEIBY: OPHICHTHIDAE 



105 



5mm 



Fig. 57. (Upper.) Anterior portion of Ophichthus gomesi larva depicting typical ophichthin gut morphology. Abbreviations: LL|_2. liver lobes 

 1-2; GB, gall bladder. (Lower.) Middle portion of Ophichthus gomesi larva depicting position of nephros relative to anus in some members of 

 the Ophichthus lineage of the tribe Ophichthini. Abbreviations: N, nephros; A, anus. 



The dorsal fin of known myrophin lai^ae has well-developed 

 pterygiophores and fin rays prior to the onset of metamorphosis 

 and migrates only a few myomeres anteriorly (4-6) during meta- 

 morphosis to reach its adult position. The dorsal fin of known 

 ophichthin larvae, which is weakly developed having only pte- 

 rygiophores and rudimentary rays in its anterior portion prior 

 to metamorphosis, must migrate 5-20 myomeres anteriorly dur- 

 ing metamorphosis in species having the dorsal fin antenor to 

 the branchial aperture as adults, and 20-50 myomeres in species 

 having the dorsal fin posterior to the branchial aperture as adults, 

 and is resorbed m species which are finless as adults. 



The subfamily Myrophinae contains two tribes (sensu 

 McCosker, 1977), the Myrophini and the Benthenchelyini. Os- 

 teological examination of adults in the tribe Myrophini indi- 

 cated the presence of three lineages consisting of Pseudomyro- 

 phis and Neenchelys; Myrophis, Ahlia. and a currently 

 undescribed genus; and Muraemchlhys and its allies. The My- 

 rophis and Muraemchlhys lineages share a common ancestor 



(Fig. 55). Larval morphology oi Myrophis, Ahlia and Muraen- 

 ichthys is very similar and supports the determination of a close 

 relationship for the two lineages. Larvae of these three genera 

 have three unconnected liver lobes, similar gut and opistho- 

 nephros morphology, and similar body length to depth ratios 

 (Fahay and Obenchain, 1978; Leiby, 1979b; Ochiai and No- 

 zawa, 1980). Pseudomyrophis larvae have three unconnected 

 liver lobes and a body length to depth ratio which is similar to 

 that of the Myrophis and Miiraenichthys lineages, but gut and 

 opisthonephros morphology is significantly different from that 

 seen in the Myrophis and Muraemchthys lineages and supports 

 the conclusion drawn from adult data that the Pseudomyrophis 

 lineage is distinct from the Myrophis and Muraenichthys lin- 

 eages. Nelson ( 1 966a) suggested that Pseudomyrophis micro- 

 pinna, the type of the genus, was congeneric with Neenchelys 

 hiutendijki, but that P. nimius, while belonging to the same 

 lineage, was separable at the generic level from either of the 

 other two species. Dean (1972) also felt that the differences 



