WHITE ET AL.: ATHERINIFORMES 



357 



with some minor exceptions. The larva of /. hawaiiensis (Fig. 

 188B) has a deeper body than any other known atheriniform 

 larva and A. msidarum (Fig. 188C) lacks the ventral melano- 

 phore series typical of the order. The ventral melanophore series 

 is also absent in Odontesthes regia (Fischer, 1963) which has 

 only sparse midlateral pigment at hatching. 



In Menidia. dorsal pigmentation can be sparse or even lacking 

 (Hildebrand, 1 922). In M. memdia. it has been reported that a 

 double row of dorsal melanophores occurs in older larvae (ca. 

 11 mm) (Lippson and Moran, 1974). However, in a smaller 

 flexion specimen (8 mm), we found a double row of melano- 

 phores in the area of the dorsal fin, but only a single row anterior 

 to the fin. The dorsal melanophore row is interrupted by the 

 dorsal fin in other atheriniform larvae as well. This pattern also 

 occurs in the melanotaeniid genus, Psendomugtl (Foster, pers. 

 comm.). It is not unusual for single melanophores to be divided 

 by a developing fin in other fishes and it is assumed here that 

 the more complex distribution of dorsal pigment in Menidia 

 and Pseudomugil is a variation on the simpler pattern seen in 

 Atherinomorus, Iso, Odontesthes and most other atheriniform 

 larvae. In Melanotaenia, a single dorsal row develops. The larval 

 morphology of Melanotaenia and Pseudomugil closely resem- 

 bles that of the other atheriniform fishes (Foster, pers. comm.). 



Larval Dentatherina mercen differ from all other known ath- 

 eriniform larvae but resemble larval Oryzias in having a double 

 row of melanophores on the nape. The melanophores on the 

 dorsal surface of the trunk are unpaired except where they are 

 interrupted by the developing dorsal fins. The larva of Bedolia 

 geayi (Fig. I88D) has the single dorsal melanophore row and 

 short gut typical of the Atheriniformes. Interestingly, the ventral 

 pigment series of Bedotia is paired, with a row of melanophores 

 flanking both sides of the anal finfold (Foster, pers. comm.). 



The early life history stages of phallostethid fishes follow closely 

 the atheriniform pattern. In both Gulaphallus mirahilts (Villa- 

 dolid and Manacop, 1934) and G. /a/a/f'r (Manacop, 1936) the 

 preanal length is short and a median series of melanophores 

 develops middorsally. The exact disposition of the dorsal me- 

 lanophores has not been described nor can it be assessed from 

 published illustrations. 



Relationships 



Two ontogenetic character states suggest that the atheriniform 

 fishes are a monophyletic group compwising an order, the Ath- 

 eriniformes, of equal standing with the Beloniformes and Cy- 

 prinodontiformes. First, the preanal length of all known ath- 

 eriniform flexion larvae, except Odontesthes dehueni, is short; 

 being approximately one-third of body length. Preanal length is 

 variable in the other two atherinomorph orders but the preanal 

 lengths of few, if any, beloniform or cyprinodontiform species 

 are this short between hatching and early flexion. The Perco- 

 morpha is thought to be the sister group of the Atherinomorpha 

 (Rosen and Parenti, 1981). In almost all primitive percomorphs, 

 preanal length exceeds that of the Atheriniformes through flex- 

 ion and approaches as much as 50-70% of body length (Ahl- 

 strom and Moser, 1976). The same can be said of the paracan- 

 thopterygian, myctophiform and aulopiform fishes (sensu Rosen; 

 1973, 1982). Preanal length is reduced in gadid fishes (Dunn, 

 this volume), but the short gut typical of the cods is always 

 looped and therefore is considered here to be nonhomologous 

 with the condition seen in the atheriniforms. Outgroup com- 

 parison thus suggests that the reduced larval preanal length can 



Fig. 1 86. (A) Atheriniform eggs. Mature egg, Atherinops affinis. San- 

 ta Catalina Island, California. LACM field no. IP-77-43; (B) Ovarian 

 egg. Euryslole enarcha. LACM 31784-5; and (C) Atherinopsis califor- 

 niensis. egg. LACM 43446-1. 



