Figure 1. — Tetrapturus angustirostris Tanaka, 1914 (from Hirasaka and Nakamura, 1947). 



T. belone, T. pfluegeri, T. albidus, and T. audax form 

 a series of equally distinct species. They also point out 

 that the placement of T. albidus and T. audax in 

 Makaira is not in accordance with their relationship 

 because they must be more closely associated with T. 

 angustirostris and T. belone and indeed with 

 Istiophorus than with any of the Makairinae ( = 

 Marlinae). These authors feel that the characters 

 separating the above five species do not deserve even 

 subgeneric rank and conclude that all should be 

 placed in the genus Tetrapturus. 



Morrow (1964) agrees with Robins and de Sylva 

 (1960, 1963) in placing T. angustirostris nearer to the 

 Atlantic and Pacific billfishes, the striped marlin, and 

 the white marlin than to the blue marlin and the 

 black marlin in the phylogeny of the Istiophoridae. 



The basic dichotomy in recognizing the 

 Istiophoridae, viz. the Tetrapturus type and Makaira 

 type (Makaira as constituted by Robins and de Sylva, 

 1960), is also supported by Ueyanagi (1963b). He con- 

 firms that, for the growth of the snout, Tetrapturus 

 and Istiophorus have a positive allometry during the 

 larval stage 2 and a negative allometry after the young 

 stage, 2 while Makaira has a positive allometry after 

 the young stage. The same subdivision, according to 

 Ueyanagi, is also true of the morphological change in 

 the dorsal fin. 



Howard (in Howard and Ueyanagi, 1965) mentions 

 that Nakamura's divisionary characters may have 

 some phylogenetic value and feels that the hierarchy 

 proposed by Robins and de Sylva, which takes into 

 consideration the only presently known characters 

 which may have phylogenetic significance, is the most 

 usable and practical offered so far. 



Nakamura, Iwai, and Matsubara (1968) include 

 three genera, Istiophorus, Tetrapturus, and Makaira, 

 in the Istiophoridae. They separate Istiophorus from 

 the other two by its much higher, saillike first dorsal 

 fin and considerably elongated ventral fins with well- 

 developed fin membrane. The distinguishing 



Tor these definitions, see Ueyanagi (1963a). 



characters between Tetrapturus and Makaira are the 

 height of the first dorsal fin, the degree in lateral com- 

 pression of the body and the dorsal profile from the 

 preocular region to the first dorsal origin. They place 

 in Tetrapturus not only the spearfish group of the 

 world, but also the Indo-Pacific striped marlin and 

 white marlin, and thus agree with Robins and de 

 Sylva (1960, 1963). 



The generic concept of Tetrapturus has, as seen 

 above, changed from what originally referred only to 

 the spearfish group to where it now includes species 

 ranging from the shortbill spearfish to the Indo- 

 Pacific striped marlin. Most authors have used the 

 form of the dorsal fin and the nature of the ventral fins 

 in separating Istiophorus from Tetrapturus. The 

 dichotomous system discussed above puts Istiophorus 

 nearer to Tetrapturus rather than to Makaira, but it 

 appears that there is current agreement that these fin 

 characters deserve generic rank although the form of 

 the first dorsal fin changes considerably with growth. 



The diagnostic characters of Tetrapturus, especial- 

 ly for adults, given by Nakamura et al. (1968) are as 

 follows: 



The first dorsal fin is slightly higher than the body depth. The 

 ventral fin rays are rather long, its fin membrane not well devel- 

 oped. The body is laterally compressed. The dorsal profile is 

 straight from the preocular region to the origin of the first dorsal 

 fin, except for the striped marlin and the white marlin. The cra- 

 nium is narrow in width and slender. The neural and haemal 

 spines on the central vertebrae nearly form a parallelogram. The 

 number of vertebrae are 12 + 12 = 24. The lateral apophysis is 

 not well developed. 



Specific 



Species Tetrapturus angustirostris 

 Tanaka, 1914. (Fig. 1) 



(Original combination) 



Identity of type specimen: 



Length: 2,000 mm measured from tip of spear to 

 upper lobe of caudal. 



40 



