604 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



angustirostns belone 



/ 



Ibidus oudox several species'^/ mdica nigricans 



Table 157. 



Comparison of Characters among Juveniles of 



.\'/PH/4S AND IsTIOPHORIDAE. 



Fig. 32 1 . Phylogenetic relationships within the family Isliophoridae 

 (from Robins and de Sylva (I960: fig. 5), names in quotations not 

 employed by Robins and de Sylva). 



anal finlets and consequently have 6 or 7 middle radials. One 

 of us (Potthoff) obtained vertebral counts from late larval and 

 juvenile specimens from the Atlantic and Indo-Pacific oceans. 

 Total counts are higher for the Atlantic and lower for the Indo- 

 Pacific with a definite separation which may indicate that there 

 are separate species. 



Diplospinus multisthatus (Fig. 318). — The larvae of Diplospi- 

 ntts are very well known, but some earlier researchers described 

 them under other names. The 1 mm specimen figured as Thyr- 

 sites prometheus in Gunther (1889) is Diplospinus because of 

 the anteriorly protruding spines on the tip of the lower jaw and 

 because of the distinct flatness of the ventral gut, although the 

 first dorsal fin spine count is too low for Diplospinus. Voss ( 1954 

 and 1 957) described Gempylus type A larvae, which definitively 

 are Diplospinus. Strasburg (1964) and Yevseyenko and Sere- 

 bryakov (1974) correctly identified and described Diplospinus 

 larvae. 



The larvae of Diplospinus (Fig. 318) superficially resemble 

 those o{ Gempylus. but the larvae of Gempylus lack the following 

 characters present in Diplospinus: two horizontal spines at the 

 lower jaw tip, serrate preopercular spine, absence of pelvic fin 

 rays, flatness of ventral gut due to posterior process of basip- 

 terygium, and pigmented gular membrane. Larval Diplospinus 

 lack the lateral body pigment stripe characteristic oi Gempylus. 

 Diplospinus juvenWes lack dorsal and anal finlets and supporting 

 middle radials, features present in Gempylus. 



Paradiplospinus gracilis.— Thelarvae of Paradiplospinus are not 

 well known. One of us (Nishikawa) has an unpublished manu- 

 script on the larval description. 



Trichiuridae 



Body elongate, strongly compressed; maxilla sheathed by 

 preorbital; anterior canine teeth strong; spinous dorsal not long- 

 er than soft dorsal (very slightly longer in occasional specimens 

 of .Aphanopus): two anal spines immediately posterior to the 

 vent; pelvic fins reduced to 1,1 or absent; caudal fin greatly 



Xtphias 



Istiophondae 



Dorsal and anal fin 

 development, ad- 

 dition 



First dorsal fin pte- 

 rygiophore inserts 

 in intcmeural 

 space number 



Dorsal and anal stay 

 posteriorly bifur- 

 cated or not 



Middle radial pres- 

 ent or absent for 

 posteriormost dor- 

 sal and anal pte- 

 rygiophore 



Number of post- 

 cleithra 



Pelvic fin and basip- 

 terygium present 

 or absent 



Caudal fin rays sup- 

 ported by how 

 many rentra includ- 

 ing urostyle 



Number of autog- 

 enous haemal 

 spines in hypural 

 complex 



One pair of ribs on 

 centra 



from a center in an 

 anterior and pos- 

 terior direction 



not bifurcated 



mostly from anterior 

 in a posterior di- 

 rection 



1 



bifurcated 



absent 



present 



absent 



present, fin ray num- 

 ber reduced 



1-4 and 13-14 



1-12 



reduced or absent; dorsal spines and intemeurals correspond to 

 vertebrae, dorsal soft rays correspond to or are slightly more 

 numerous (in .Aphanopus and Benihodesmus) than vertebrae 

 (Table 155); vertebrae numerous, 98-99 (.iphanopus) to 192 

 (Eupleurogrammus) (Table 1 54); nbs feeble, sessile (Regan, 1 909; 

 Tucker, 1956). The family contains 9 genera and at least 18 

 species (Parin and Mikhailin. 1981). Most genera have only one 

 or two species; Benihodesmus has at least 8 valid described 

 species (Parin and Bekker, 1972; Parin, 1976, 1978). 



Tucker (1956) recognized three subfamilies within the Trich- 

 iuridae (Fig. 319); Aphanopinae (Aplianopus, Benihodesmus, 

 and Diplospinus); Lepidopinae {Lepidopus. .Assurger. Tentori- 

 ceps, Evoxymeiopon, and Eupleurogrammus). and Trichiurinae 

 {Trichiurus and Lepturacanthus). Diplospinus and Paradiplo- 

 spinus have been transferred from a primitive position in the 

 Trichiuridae to an advanced position in the Gempylidae by 

 Russo (1983). 



Development 



Information on larval trichiunds is scarce. Of 9 trichiurid 

 genera only 3 species in 3 different genera have been described. 

 The known trichiurid larvae are characterized by very long bod- 

 ies, more than 100 myomeres, pelvic fins reduced or absent, 

 serrate spines in the first dorsal and anal fins and in the pelvic 

 fin if present. The first dorsal fin is the first fin to develop. The 



