372 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



Table 99. Some Characteristics of Eggs of Lampriform Fishes. 



Table 100. PatternsofPterygiophoreInterdigitationin Anteri- 

 or Interneural Spaces of Young Lampriform Fishes. Within inter- 

 neural spaces, P indicates a predorsal element and numerals indicate 

 numbers of pterygiophores. 



highly pigmented serial swellings; stout, well developed pelvic 

 eleinents often with fleshy sheaths and highly pigmented ter- 

 minal swellings; and snout to vent lengths approximately 40- 

 60% NL (Figs. 193, 195). Larvae of Metavelifer and Lampris 

 are slender at small sizes but Lampris larvae (and presumably 

 veliferids) rapidly increase in body depth (Fig. 196). By 10.6 

 mm SL (Fig. 197), larval Lampris have assumed the character- 

 istic adult, deep-bodied form. Larvae of the remaining genera 

 are also slender at hatching but become rapidly elongate with 

 growth. In these taxa, gut length may vary during ontogeny, 

 increasing to 80-90% SL in Lopholus. Eumecichthys and Re- 

 galecus. Gut length at transformation distinguishes these genera 

 from 7ai. Trachipterus, Dcsmodema and Radiicephalus. 



Anterior dorsal rays are supported by a fleshy base in early 

 larval stages (Figs. 193, 195) and by modified radials first ap- 

 pearing as cartilage. The fleshy base and associated radials sup- 

 porting these rays are sometimes damaged in capture and torn 

 away from the cranium. This artifactual condition is occasion- 

 ally referenced in older literature as a "nuchal lobe"" (Hubbs, 

 1925:475) and "nuchal pennant" (Walters and Fitch, 1960:442- 

 443). In larval trachipterid, lophotid and regalecid fishes, the 

 first two dorsal elements are supported by elongate, stout radials, 

 the second of which serially supports succeeding radials of vary- 

 ing number (Table 100). These elements interdigitate in inter- 

 neural spaces and pterygiophore interdigitation patterns vary at 

 the generic level (Rosenblatt and Butler, 1977; Table 100). Law- 

 pris and Metavelifer possess a predorsal element which inter- 

 digitates in the first neural space. These genera (and presumably 

 Velifer) are unique in the possession of this character (Table 

 100). In addition, the morphology of the anterior modified ra- 

 dials varies with ontogeny. The rostrum or "horn" of Eume- 

 cichthys e\ongaies duringgrowth to twice its original length (Far- 



Inlemeural space 



Species 



Z. cristatus 

 Trachipterus sp. 

 R. glesne 

 Desmodema spp. 

 R. elongatus 

 M. muitiradiatus 

 L. gultatus 



in and Pokhil'skaya, 1968). Oelschlager (1976a) considers the 

 lophotid "horn'" to be supported by modifications of the frontals 

 and the supraoccipital (termed the "fronto-occipital carina"), 

 however these highly modified dorsal rays are likely supported 

 by dorsal fin radials which may fuse to cranial bones in adults. 

 In Dcsmodema. anterior dorsal rays are elongate in juveniles 

 but lost at transition (Rosenblatt and Butler, 1977). Presumably, 

 pterygiophores supporting these rays and interdigitating anterior 

 to the first neural spine (Table 100) are retained in adults. 



Development of pelvic fin elements is precocious in all known 

 larval Lampriformes (Figs. 193, 195-200) and characterized by 

 reduction of ray number, length or both in some genera. In S. 

 chordalus (Figs. 199 and 200), a single elongate pelvic element 

 in early larvae becomes increasingly long and stout with de- 

 velopment, persisting until around 70 mm SL. Adult 5. chor- 

 datus (Regan, 1924; Table 98) lack a pelvic fin. A similar de- 

 velopmental sequence may occur in Desmodema which loses 

 pelvic elements by 173 mm SL (Rosenblatt and Butler, 1977) 

 and in R. elongatus (Harrison and Palmer, 1968). In Regalecus 

 and Agrostichthys {Oe\sch\a.ge:v, 1978a) the pelvic fin is retained 

 as a persistent larval floatation device that also serves in loco- 

 motion and taste perception. 



The pectoral fin is the last to complete difTerentiation in larval 

 lampriformes. In our material, pectoral rays are incompletely 

 developed at 18.4 mm SL in R. elongatus (Fig. 198); 21.4 mm 

 SL in 5. chordatus (Fig. 200); and 29 mm SL in Trachipterus 

 sp. Pectoral development is most rapid in L. gultatus which 

 possesses adult counts by 10.6 mm SL (Fig. 197). Adults ofthis 

 species possess a strongly developed, lunate pectoral (Rosenblatt 

 and Johnson, 1976) which may also be important in locomotion 

 of larvae. Pectoral morphology and insertion vary consider- 

 ably among lampriform genera and are of systematic value, 

 although no comprehensive treatment exists. 



Among lampriform genera, caudal morphology exhibits the 

 greatest potential for taxonomic and systematic evaluation. Ro- 

 senblatt and Butler (1977) have demonstrated the utility ofthis 

 character in distinguishing juvenile and adults of Trachipterus 

 and Desmodema and the details of caudal morphology (Table 

 98 and see Gosline, 1961; Hulley and Rau, 1969; Oelschlager, 

 1974; Patterson, 1968; Pietsch, 1978a; and Rosen, 1973 for 

 illustrations of caudal skeletons in various lampriform genera) 

 clearly delimit all other taxa, with the possible exception of 

 Agrostichthys {OehcMager, 1978b). Diff"erentiation of caudal 

 elements occurs early in development, rendering caudal mor- 

 phology an important larval identification criterion. Although 

 full developmental series are not available for most forms, the 



