212 



ONTOGENY AND SYSTEMATICS OF FISHES -AHLSTROM SYMPOSIUM 



last elements being rarely visible in larvae less than 20 mm. 

 Apart from the length at metamorphosis varying between 25 

 and 45 mm among species, pigmentation pattern is usually the 

 only useful character for specific identification. Once established 

 these pigment patterns, mostly restricted to the tail, are retained 

 throughout the larval stages, although a few species are known 

 to be unpigmented throughout all or part of the larval period. 



Scopelarchidae (see R. K. Johnson, this volume). 



Bathysauhdae (Fig. 1 1 IC).— This deep-water benthic family 

 consists of two species of synchronous hermaphrodites, Bathy- 

 saurus mollis and B. ferox (=B. agassizi) (Sulak, pers. comm.; 

 Wenner, 1978). 



Pelagic eggs are unknown. Maximum size of mature ovarian 

 eggs in B. ferox is 1.2 mm in diameter (Wenner, 1978). So- 

 called "Macristium" forms are now proved to be larval Bath- 

 ysaunis (Rosen, 1971; Johnson, 1974a); at least several of the 

 five known "Macristium" larvae (20-83 mm) are positively 

 identified with B. mollis. Morphology and osteology of these 

 specimens have been closely studied, revealing many charac- 

 teristic features such as unusually elongated fins, anterior place- 

 ment of dorsal and pelvic fins, raised bases of dorsal and anal 

 fins, long gut (coiled or uncoiled) terminating just in front of 

 anal fin origin, six peritoneal saddle-shaped pigment sections 

 all evenly spaced, and development of a pattern of lateral bars 

 in some specimens. Besides this last feature, meristic differences 

 serve to distinguish two species despite considerable variation. 



Metamorphosis may take place gradually at exceptionally large 

 sizes (more than 83 mm). Accompanying changes include short- 

 ening of fins, expansion of the gape with necessary associated 

 changes in head bones and associated anatomy, backward shift 

 of the dorsal fin origin, and darkening of the body surface, oral 

 cavity and peritoneum. 



Harpadontidae (Fig. 1 1 ID-E). — Two genera are recently in- 

 cluded here (Sulak, 1977; Johnson, 1982). Harpadon comprises 

 at least four species living in nearshore waters, estuarine and 

 relatively deep continental shelf waters of the Indo-Pacific. Crit- 

 ical systematic revision of this genus is now in progress (Schmitz, 

 pers. comm.). A pelagic egg referred to H. nehereus in Delsman 

 ( 1929c) appears invalid (Delsman and Hardenberg, 1934). Early 

 developmental stages are poorly studied; only two specimens 

 of//, nehereus (25.2, and ca. 40 mm) have been illustrated and/ 

 or briefly described (Delsman and Hardenberg, 1934; Okiyama, 

 1979b). A juvenile of 55 mm is the smallest specimen of the 

 deep water congener, //. microchir, available in ORI collections. 

 Early stages are readily discriminated from most other myc- 



tophiform larvae by the exceptionally high numbers of bran- 

 chiostegal rays (16-27) and the following characters: elongate 

 compressed body with large head and mouth, short snout (due 

 to the forward shift of eyes), scant pigmentation except seven 

 pairs of peritoneal pigment sections, the last two closer together 

 than the others, and extension of the lateral line scales onto the 

 caudal fin. Of these rather advanced developmental features, 

 pigmentation pattern may be common to the earlier stages. 

 Apparently, long pectoral and pelvic fins are peculiar to //. 

 nehereus. Also, //. microchir is more lightly pigmented than //. 

 nehereus at similar lengths. 



Metamorphosis seems gradual. If the occurrence of melano- 

 phores over the stomach is of significance in defining this pro- 

 cess, transformation is completed by 35 mm in //. nehereus. 



There are about 1 5 species of Saurida with highest diversity 

 in the Western Pacific. Planktonic eggs are known for S. elon- 

 gata, S. wanieso. and S. tumbil besides several unidentifiable 

 species (Mito, 1961a; Zvjagina, 1965a; Venkataramanujan and 

 Ramanoorthi, 1981). These are spherical, 1.0-1.3 mm in di- 

 ameter, transparent, without oil globules and with a narrow per- 

 ivitelline space. Hexagonal sculpturing on the chorion (0.03- 

 0.05 mm in mesh size) is either present (S. wanieso and S. 

 tumbil) or absent (S. elongata). Early developmental stages are 

 known for 9 species. Of these, complete developmental series 

 are available for at least 4 Pacific species, S. tumbil, S. elongata. 

 S. wanieso and S. gracilis (Dileep, 1977; Ozawa, 1983) and the 

 Atlantic species, 5. brasiliensis (K\x(i.omtX]f.ma.. 1980). These lar- 

 vae are extremely similar to those of Harpadon. except for the 

 lower numbers of branchiostegals and invariably short fins. 

 Complete absence of the preanal finfold in the early stages is 

 peculiar to this genus (Ozawa, 1983). Except for S. brasiliensis. 

 however, these are divided into two types on the basis of pig- 

 mentation pattern. One of these consisting of S. gracilis and 

 probably some Atlantic congeners is characterized by evenly 

 spaced peritoneal pigment sections of similar size and simul- 

 taneous differentiation. In addition, prominent pigment along 

 the anal fin base and on the caudal fins may be diagnostic for 

 this type. 5. gracilis larvae uniquely develop a small choroid 

 mass on the ventral side of narrow eyes (Ozawa, 1983) while 

 nothing is mentioned in this regard for Hawaiian larvae (Miller 

 et al., 1979). Remaining larvae belong to the second type in 

 which the terminal pigment section is smaller and later-ap- 

 pearing than the anterior sections. Other pigment is also scarse 

 or absent in this latter type, where specific differences are known 

 in the size of pigment sections and vertebral numbers. Meta- 

 morphosis occurs fairly gradually with considerable variation 

 in size among species, but is usually complete before 40 mm 

 (Gibbs, 1959). 



Fig. 110. (A) Ipnops agassizi. 13.9 mm SL, from Okiyama (1981); (B) Balhytyphlops manonae. 13.1 mm, from Okiyama (1972); (C) 

 Bathymicrops brevianalis. 70.0 mm, from tropical central Pacific, ORI collection; (D) Bathypterois sp. (pigmented type), from northeast of 

 Australia, Southwest Fisheries Center (SWFC) collection; (E): Bathypterois viridensts (unpigmented type), from Fahay (1983). 



Fig. 111. (A) Scopelosaurus smilhii. 1 3.4 mm SL, from southwestern Pacific, ORI collection; (B) the same, dorsal view of head; (C) Bathysaurus 

 ferox. 33.0 mm, from Marshall (1961); (D) Harpadon nehereus. 25.2 mm, from East China Sea, ORI collection; (E) Saunda undosquamis. 15.6 

 mm, from Okiyama (1974b); (F) Synodus lucioceps. 10.5 mm, from California current region. SWFC collection; (G) Trachinocephatus myops. 

 21.3 mm, from Zvjagina (1965a). 



Fig. 112. (A) Atepisaurus brevirostris. 12.1 mm, from Rofen(1966b);(B)/l./era>:. 10.0 mm, from central Pacific near Hawaii, SWFC collection; 

 (C) Anotopterus pharao, 14.2 mm, from California current region, SWFC collection; (D) Omosudis lowei (central western Atlantic specimen), 

 11.8 mm, from Rofen (1966b); (E-F) O. lowei. 22.5 mm, from tropical western Pacific, ORI collection, showing dorsal view of head. 



