612 



ONTOGENY AND SYSTEM ATICS OF FISHES- AHLSTROM SYMPOSIUM 



Class intervals of numbers of coincident characters 

 state between pairs of genera 



Group B 



Fig. 330. Dendogram depicting larval relationships among 12genera 

 of Scombrinae (from Okiyama and Ueyanagi, 1978: fig. 2). 



snout is greatest in the larval period. In the case of T. audax, 

 however, the snout/body length value is not so high among 

 Tetraplurus, and it is thought to be intermediate between Ma- 

 kaira and Tetraptums. The pattern of morphological change in 

 snout length with ontogeny in various genera corresponds to the 

 classification of adult fishes and is thought to reflect phylogeny 

 among the genera of istiophorid fishes (Ueyanagi, 1963b). 



Table 1 58. Present Status of the Larval Fish Taxonomy of the 

 Family Scombridae (Modified after Okiyama and Ueyanagi, 1978: 



TABLE 1). 



Table 159. Presumed Phylogenetically Important Larval 

 (Chiefly Advanced Postlarval or Early Juvenile Stages) Char- 

 acters as Coded State for Comparison of 12 Genera of the 

 Subfamily Scombrinae. (After Okiyama and Ueyanagi, 1978: table 2). 



Subfamily, tnbe. 

 and genus 



Present state of the lai^al fish taxonomy 



Genenc level 



Species level 



Scombrinae 



Scombrini 



Scomber well established 



RastreUiger well established 



Scomberomorini 



Grammatorcynus well established 

 Scomberomorus well established 



Acanthocybium 

 Sardini 



Orcynopsis 

 Cybiosarda 

 Sarda 



Gymnosarda 

 Thunnini 



Allothunnus 



AlLXlS 



Euthynnus 



Katsuwonus 



Thunnus 



well established 



no information 

 no information 

 rather well estab- 

 lished 



well established 



well established 

 well established 

 well established 

 well established 

 well established 



well established 

 well established 



well established 

 incomplete or none 

 for many species 

 well established 



no information 



no information 



no problem in identi- 

 fication but poor 

 information 



well established 



well established 



incomplete 



well established 



well established 



established for most, 

 but identification 

 very difficult to ac- 

 complish 



Xiphiidae 



Hypural plate mostly covered by caudal fin rays; caudal fin 

 supported by only two centra (urostyle and preural centrum 2); 

 long depressed rostrum formed only by united premaxillae; na- 

 sals not forming part of the bill; predentary bone absent; su- 

 pratemporal absent; one postcleithrum; anteriormost dorsal pte- 

 rygiophore inserts in second (rather than third) intemeural space; 

 no teeth in adult; pectoral fins placed low; scales lost in adult; 

 pelvic fins and pelvic girdle absent; vertebrae few, 15-1- 11 = 

 26; neural and haemal spines not expanded; ribs present on only 

 the first four centra and the last two precaudal vertebrae (Regan, 

 1909; Gregory and Conrad, 1937; Potthofl'and Kelley, 1982; 

 G. D. Johnson, pers. comm.). Monotypic, contains only Xiphias 

 gladius. 



Development 



Xiphias gladius (Fig. 323). — Eggs and larvae of Xiphias have 

 been described by a number of authors during the 1 9th and 20th 

 centuries as summarized by Richards (1974). The most recent 

 and complete description is by Arata (1954) and drawings of a 

 developmental series are by Taning (1955). Osteological devel- 

 opment was studied by Potthoffand Kelley (1982). 



Early larvae of swordfish are distinguished by having overall 

 body pigmentation and lacking the strong pterotic and pre- 

 opercular spines so characteristic of the istiophorids (Richards, 

 1974). Late preflexion larvae to juveniles acquire prickly squa- 



