COLLETTE ET AL.: BELONIFORMES 



341 



do (Evans, 1962— Hirundichthys affinis; Vijayarghavan, 1973 — 

 H. coromandelensis; Vijayaraghavan, 1975 — Cypselurus spilop- 

 terus and Kovalevskaya, 1965 — Cheilopogon katoptron) are of 

 embryos or newly hatched larvae and, except for Kovalevskaya 

 (1965), were hatched in the laboratory (Fig. 177H). In these 

 examples the preanal finfold was small and soon lost. We have 

 examined field-collected yolk-sac Cheilopogon (pTes\imab\y Ch. 

 pinnatibarbatus californicus) without finding a preanal finfold 

 (Fig. 177G). Perhaps some exocoetids have a preanal finfold, 

 but lose it soon after hatching. If so, most field-collected spec- 

 imens may have already lost the preanal finfold by the minimum 

 sizes typically illustrated. 



Fin formation generally begins during the embryonic stages 

 or soon after hatching. In fact, flexion of the caudal fin precedes 

 hatching in flyingfishes (Ahlstrom and Moser, 1980). In the 

 scomberesocids, belonids and hemiramphids, caudal, dorsal and 

 anal fins generally form first followed by the pectorals and lastly 

 the pelvics. Pectoral and pelvic buds as well as dorsal and anal 

 anlagen are typically present at hatching in exocoetids. Pectoral 

 fins form last in exocoetids, after the pelvic fins. 



Belonids, scomberesocids and exocoetids generally hatch with 

 heavy, uniform pigmentation formed or forming over essentially 

 the entire body (Fig. 1 778, C, and G). Exceptions are the fresh- 

 water needlefish Xenentodon cancila. which has 9-10 saddle- 

 shaped dorsal aggregations plus a ventrolateral stripe (Fig. 1 77D) 

 and some exocoetids of the genera Parexocoetus and Cheilo- 

 pogon. which have patterns somewhat reminiscent of the hem- 

 iramphids (compare Fig. 177E and H). This pattern consists of 

 three rows of melanophores on each side of the body, one dorsal, 

 one lateral and one ventral. Two hemiramphids reported to be 

 exceptions to this are Hyporhamphus quoyi and Hemiramphus 

 marginatus. These species hatch with pigment over the entire 

 body; a pattern reminiscent of most other beloniforms. The 

 pigment pattern in adrianichthyids resembles that in hemiram- 

 phids except dorsally where the adrianichthyids have a single 

 middorsal row of melanophores (Fig. 181 A), similar to the con- 

 dition observed in Atheriniformes (see White et al., this volume) 

 rather than the double row typical of most hemiramphids (Fig. 

 177F). 



Specialized Ontogenetic Stages 

 During post-embryonic development, beloniform fishes 

 undergo a number of complex changes.Their larvae differ fairly 

 strongly from juveniles and the juveniles are frequently unlike 

 adults. Juveniles of related species frequently differ more from 

 each other than do larvae or adults. In this section, notable 

 ontogenetic changes are described for several character suites 

 in the four families of the Exocoetoidei. Adrianichthyoids lack 

 specialized ontogenetic stages. 



Jaws, beaks, and barbels 



Scomberesocidae.— Juveniles (20-40 mm SL) have slightly 

 elongate upper and lower jaws but no prominent beaks (Fig. 

 18 IB; Hubbs and Wisner, 1980: fig. a). At about 60 mm 

 SL, both upper and lower jaws, but especially the lower jaw, 

 elongate in Scomberesox and Namchthys. Elongation continues 

 in both taxa to 100-120 mm SL. Both jaws elongate almost 

 equally in Scomberesox; the lower jaw exceeds the upper in 



Fig. 176. Exocoetidae eggs. (A) Exocoetus volilansAM) t'odiator acu- 

 lus pacificus: (C) Hirundichthys coromandelensis. (From: A. Parin and 

 Gorbunova, 1964. B. Breder, 1938. C. Vijayaraghavan, 1973.) 



