MARINE SILVER HATCHETFISHES — SCHULTZ 643 



Polyipnus japonicus, new species 



Figure 19 



Holotype: SIO H53-367, Kii Strait, Japan, Oct. 23-24, 1953, 

 midwater trawl by S. F. Baird, standard length 12.5 mm. 



Description: Measurements made on the holotype, the only 

 known specimen, are given in table 7, p. 638; the counts made are given 

 in table 6, p. 636. 



Color: The color pattern is shown in figure 19, p. 631. 



Range: This species is known only from Japan. 



Remarks: This species along with P. fraseri is characterized by 

 having only four anal photophores, fewer than any other species of 

 Polyipnus. P. japonicus is most closely related to P. fraseri but 

 differs from that species as follows : 



The posttemporal spine in P. japonicus is simple, very small, and 

 without spines arising from its side or the base whereas the post- 

 temporal spine in fraseri is long, strong, and has two strong basal 

 spines; the posterior edge of both the supracleithrum and bony prc- 

 opecle are serrated in fraseri whereas they are smooth in japonicus ; 

 the lower bony edge in both species is serrated. Although there are 

 a few minor differences in body proportions between the two species, 

 these might result from the great differences in size. The length of 

 the posttemporal spine, however, is usually proportionately longer in 

 small specimens of Polyipnus than in the larger specimens of the 

 same species; hence, I conclude that the spine of japonicus, only 16 

 thousandths of the standard length, is significantly shorter than 

 that of fraseri, which is 160 thousandths. 



The first two pair of abdominal photophores in fraseri are out of 

 line with the others, whereas in japonicus all abdominal photophores 

 are in line, as is usual in Polyipnus. I presume the unusual arrange- 

 ment of abdominal photophores in fraseri may be an abnormality. 



Radiographs of this species did not show vertebrae clearly to enable 

 me to make a count; therefore, this species is not included in table 1. 



The species is named japonicus in reference to the region where the 

 holotype was collected. 



Polyipnus unispinus Schultz 



Figure 20 



Polyipnus unispinus Schultz, Proc. U.S. Nat. Mus., vol. 86, p. 137, fig. 43, 1938 

 (Philippines) . 



Study material: Holotype, USNM 103153, Albatross station 

 5451, lat, 13°22'22" N., long. 124°00'48" E., depth 380 fathoms, 

 June 5, 1909, 20.5 mm. standard length. Para types, USNM 103029, 

 same data as holotype, 5 specimens, 16 to 19 mm. Nontypes, 



