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Fishery Bulletin 101(2) 



Both H. melanochir and H. regularis share charac- 

 ters common to other described hemiramphid larvae. 

 They are generally characterized by their lack of 

 head or fin spines; elongate body; long straight gut; 

 extended lower jaw; a main pigmentation pattern con- 

 sisting of rows of melanophores on the dorsal, lateral, 

 and ventral surfaces of the body; and advanced state 

 of development at hatching (Collette et al., 1984; 

 Watson, 1996; Trnski et al., 2000). Although the size 

 at which fins develop varies slightly between H. mela- 

 nochir and H. regularis, the sequence of development 

 for both species is the same as that for most hemiram- 

 phids, i.e. C -> D. A -► P, -► P.^ (Collette et al., 1984). 



Hyporhamphus melanochir larvae are distinguish- 

 able from H. regularis by 1) having 58-61 vertebrae 

 (vs. 51-54 for H. regularis); 2) having 12-15 mela- 

 nophore pairs in longitudinal rows along the dorsal 

 margin between the head and origin of the dorsal 

 fin (vs. 19-22 for H. regularis); and 3) the absence 

 of a large ventral pigment blotch anteriorly on the 

 gut and isthmus which is present in H. regularis. 

 Despite the difficulty in counting myomeres, either 

 the number of vertebrae in cleared and stained specimens 

 or the number of myomeres between the pectoral-fin base 

 and anus (usually three less than the number of precaudal 

 vertebrae; see Tables 2 and 4) revealed a consistent differ- 

 ence between both species. 



Figure 4 



Pigmentation of an 8.7-mm Hyporhamphus regularis larva. (Al 

 Dorsal view; arrows indicate the margins of the 19-22 melano- 

 phore pairs in longitudinal rows. ( B ) Ventral view; arrow indicates 

 the ventral pigment blotch. 



The geographic distributions of larval H. melanochir 

 and H. regularis were separate in most samples; only three 

 H. melanochir were found among H. regularis from Barker 

 Inlet, whereas no H. regularis were among H. melanochir 

 from the Bay of Shoals or Gulf St. Vincent. Larvae of other 



