234 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



Hygophum. — Fig. 1 17A-C; diagnostic pattern of melanophores 

 at the cleithral symphysis and isthmus region consisting of paired 

 pigment dashes that form a median Hne as the series extends 

 forward on the isthmus; Br, photophore forms late in larval 

 period; three morphs. H. proximum-H. hygomi-H. benoiti-H. 

 hanseni-H. brunni: Fig. 1 1 7A; eye moderately narrow with con- 

 ical choroid tissue; pigment sparse in most species with some 

 lateral gut spots in all species; some species may have pigment 

 on hypaxial myosepta, jaws, lateral cleithral region, base of cau- 

 dal rays. H. atratuin-H. reinhardti: Fig. 1 1 7C; body very slen- 

 der; head flat; eyes very narrow, on short stalks; elongate conical 

 choroid mass; gut almost straight, small diameter; pigment se- 

 ries along lateral gut and hypaxial myosepta; pigment at caudal 

 fin base; pigment on lower jaw symphysis in H. atratum. H. 

 macrochir-H. taaningi: Fig. 117B; body and head deep and 

 laterally compressed; eyes large, relatively wide; no choroid tis- 

 sue; anterior gut section narrow in diameter, opening dorsally 

 into somewhat saccular posterior section; H. macrochir has pig- 

 ment on upper and lower jaw and a patch of melanophores on 

 posterior gut section; H. taaningi has pigment on gular region 

 and lateral surface of cleithrum. 



Symbolophorus. — Fig. 1 17D; head broad, somewhat flat; eyes 

 slightly stalked, conical choroid mass; pectoral fin large with 

 supernumerary rays, base wing-shaped, rays ossify early; pelvic 

 fin large, early-forming in some species; dorsal finfold well de- 

 veloped with fin base forming in it; pigment series on lateral 

 gut and postanal ventral midline in preflexion larvae; pigment 

 on snout, hindbrain, lateral cleithral region, isthmus, paired fins. 



Myctophum.— Figs. 1 17E, F and 1 18A-E; at least five distinct 

 morphs, all but M. aurolaternatum with enlarged fan-shaped 

 pectoral fins, some with supernumerary rays and early ossifi- 

 cation; conical choroid mass. M. aurolaternatum: Fig. 117F; 

 body very slender; head somewhat flat; eyes small, on elongate 

 stalks; gut straight, at midbody becomes trailing, extending to 

 well beyond caudal fin; dorsal finfold well developed, fin base 

 forms at its margin; pigment series on lateral gut, evenly dis- 

 tributed on trailing section, except heavier near terminus; pig- 

 ment on jaws, isthmus, opercle, branchiostegal membrane, pec- 

 toral fin, anal fin base, caudal fin. M. nitidulum-M . punctatum: 

 Fig. 1 1 7E; body moderately slender to slightly deep; head broad, 

 somewhat flat in preflexion stage; eyes on short stalks; numerous 

 small melanophores on snout, jaws, brain, isthmus, branchio- 

 stegal membrane; two rows of melanophores on ventral surface 

 of gut; opposing melanophores on postanal dorsal and ventral 

 midline; pigment on pectoral fin base and blade and at base of 

 caudal rays. M. phengodes: Fig. 1 1 8 A; body and head moder- 

 ately deep; similar to M. nitidulum, except pigment sparse and 

 eyes not stalked; pigment at base of pectoral fin rays. M. spi- 

 nosum-M. lychnohium: Fig. 1 18E; head with convex dorsal pro- 

 file and long snout giving the larva a fusiform appearance; long 

 axis of eye rotated towards horizontal; photophores (Table 62); 

 head heavily pigmented on jaws, brain, postorbital and oper- 

 cular regions; pigment above gut on trunk, embedded in my- 

 osepta in M. spinosum; opposing dorsal and ventral midline 

 blotches, larger and more deeply embedded in M. spinosum 

 with embedded myoseptal pigment along horizontal septum; 

 blotch at base of caudal rays. M. asperum-M . brachygnathum- 

 M. obtusirostre-M. selenops: Fig. 118B-D; body deep, robust; 

 head broad, deep with convex dorsal profile and large snout; 

 eye relatively larger than in other morphs; choroid tissue broadly 



conical, except in M. selenops where it is elongate and pigmented 

 at tip; photophores (Table 62); head pigment similar to M. 

 spinosum; most species have heavy pigment lateral to cleithra 

 and on pectoral fin bases; all species lack trunk and tail pigment, 

 except M. asperum which has extensive embedded myoseptal 

 and dorsal/ventral midline blotches. 



Loweina. — Fig. 1 1 9 A; body and head moderately deep, laterally 

 compressed; dorsal and anal fins displaced far posteriad; dorsal 

 and ventral finfolds greatly enlarged and conspicuously pig- 

 mented to produce a disc-shaped profile; eyes large; gut with 

 expanded anterior section and enlarged terminal section; pec- 

 toral fin large with lower-most ray elongate, ornamented with 

 pigmented spatulations; interorbital pigment band; pigment at 

 lateral cleithral surface, dorsal fin origin, and opposing midline 

 blotches at caudal peduncle region. 



Tarletonbeania. — Fig. 1 198; similar to Loweina. except median 

 fins displaced less posteriad; eye narrower and with lunate cho- 

 roid mass; four melanophores on periphery of brain, two me- 

 lanophore series on ventrum of gut. 



Gonichthys. — Fig. 1 1 9C; body and head deep and laterally com- 

 pressed, leaf-like; snout large, angulate in profile; eye small with 

 elongate conical choroid mass, pigmented at tip; enlarged dorsal 

 and ventral finfolds; pectoral fins moderately large; pigment on 

 snout, jaws, midline of brain, postorbital and opercular regions; 

 pigment on lateral hindgut and on trunk above gut; series of 

 embedded blotches on dorsal midline of body, opposing blotch- 

 es on postanal ventral midline; large pigment patch on lateral 

 caudal peduncle region in G. tenuiculus; heavy embedded pig- 

 ment streak along horizontal septum in G. coccoi. 



Centrobranchus. — Fig. 119D; morphology similar to Gonich- 

 thys except snout markedly blunt and rounded and terminal gut 

 flexure less acute; two morphs. C. choerocephalus-C. breviros- 

 tris-C. nigroocellatus: Fig. 1 19D; eye very narrow with unpig- 

 mented choroid mass that exceeds it in length; pigment sparse; 

 some at postorbital-opercular region, branchiostegal membrane, 

 ventral surface of liver. C. andrae. eye wider than in above 

 morph and with short conical choroid mass; pigment extensive, 

 on snout, upper jaw, dorsal brain, opercle, branchiostegal mem- 

 brane, lateral hindgut, ventral surface of liver, pectoral fin base; 

 embedded spots along dorsal midline with opposing spots along 

 postanal ventral midline; embedded spots along horizontal sep- 

 tum in caudal peduncle region. 



Lampanyctinae 



Notolychnus. — Fig. 1 20A; head relatively large with moderately 

 elongate snout; eyes usually narrow, often irregular in shape; gut 

 short, more so in preflexion stage; no photophores, even Br, 

 lacking; pigment on lateral hindgut, gas bladder, base of caudal 

 rays; a persistent but sparse postanal ventral midline series. 



Lobianchia. — Fig. 120B, C; body deep, robust; head broad with 

 large snout; pectoral fins large; blade wing-shaped with upper 

 rays longer than others; photophores (Table 62); head unpig- 

 mented; pigment on trunk, on gut below pectoral fin base, on 

 pectoral fin base and blade, embedded in gut region anterior to 

 pectoral fin base, along anal fin base, and at base of caudal rays; 

 embedded melanophores in myosepta above pectoral fin be- 

 coming extensive in postflexion stage; two morphs. L. dofleini: 

 Fig. 120B; eye small, narrow, with lunate to squarish choroid 



