GORDON ET AL.: OPHIDIIFORMES 



313 



Table 86. Meristic Variation in Eastern North Pacific Species of Cusk-Eels. Sample size is indicated in parentheses below the range. 



Fig. 14; plate XLV, Figs. 3 and 4) with C. acus (plate XLV, Fig. 

 5). 



Prejuveniles. —Ophidiine lai^ae are pelagic, and the develop- 

 ment of most species proceeds directly without an abrupt tran- 

 sition period. The larvae of Ophidian selenops, however, are 

 extremely elongate and attain a length of 40 mm SL before 

 reduction of intervertebral spaces causes a reduction in total 

 length to about 24 mm (Gordon, 1982). Soon after this trans- 

 formation the body shape approaches the juvenile form and the 

 larvae become benthic. Elongate larvae identified here as O. 

 nocomis have a similar morphology (Fig. 1 59D). Most ophidiine 

 species probably become benthic at about 25-30 mm SL. Chi- 

 lara taylori and Farophidion, however, have extended nektonic 

 prejuvenile stages (Lea, 1980). The prejuvenile stage of C tay- 

 lori reaches 80 mm SL and was described as Ophidion nova- 

 culum by Harry (1951). 



A specialized prejuvenile stage, known as a tenuis larva, has 

 been described for some Carapus species and Echiodon dawsoni 

 and is characterized by the absence of a vexillum and an initial 

 lengthening and subsequent reduction in total length (Emery, 

 1880; Arnold, 1956; Padoa, 1956j; Strasburg, 1961; Hipeau- 

 Jacquotte. 1967;Gustato, 1976;Trott, 1981; Williams and Shipp, 

 1982). The stage is poorly known and has been reported as an 

 obligate inquiline parasite (Trott, 1981), a free-living benthic 

 form (Trott. 1981), and a pelagic form sometimes attracted to 

 nightlights (Smith et al., 1981). 



Meristic characters. — MensUc characters that are observable in 

 ophidiine larvae include myomere number, vertebral formula 

 (precaudal plus caudal vertebrae), dorsal fin ray number and 

 anal fin ray number. Pectoral fin ray number and gill raker 

 development, which are important taxonomically in adults, can- 

 not be considered complete in pelagic larvae. Meristic characters 

 show large variation within species. In many cases, published 

 ranges for these characters are based upon too few specimens 

 to accurately depict the range of variation. In addition, meristic 

 data show broad range overlap between several species and 

 caution should be employed. Positive identification of larvae 

 based solely on meristic characters, however, can be made for 

 some western Atlantic species, including Ophidion selenops. O. 

 nocomis, Otophidium omostigmum. Oto. dormitator. Oto. 

 chickcharney and Lepophidium staurophor. In the eastern Pa- 

 cific, larvae of Chilara taylori and Otophidium indefatigabile 

 are identifiable based on meristics. Ranges of meristic characters 

 for western Atlantic ophidiines are given in Table 85 and for 

 eastern Pacific ophidiines in Table 86. Several species of the 

 genera Ophidion and Lepophidium from the western Atlantic 

 are presently undescribed. and taxonomic questions remain to 

 be resolved (C. R. Robins, pers. comm.). 



Development of the ophidiine vertebral column and fins was 

 described by Gordon ( 1 982). Total myomeres in larvae compare 

 closely with total vertebrae in adults. The number of preanal 

 myomeres present prior to coiling of the gut is usually greater 

 than the number of precaudal vertebrae in adults, because the 



