FISHERY BULLETIN VOL 76. NO 3 



DIODON EYDOUXII BRISSOUT DE 

 BARNEVILLE 



Pelagic Porcupinefish (Figure 7) 



Diodon cyduuxii Brissout de Barneville 1846:142 



(eastern Pacific); Troschel 1847:364; Dumeril 



1855:278. 

 Diodon melanopsis Kaup 1855:228 (no locality 



given). 

 Diodon spinosissimu.s (not of Cuvier): Giinther 



1870:307 (Cape of Good Hope, Siam). 



Diagnosis. — A slender-bodied Diodon , head width 

 0.25-0.30, peduncle length 0.16-0.22. Caudal 

 peduncle armed dorsally with short spines. Body 

 spines long and slender, moderate in number, S-D 

 spines 13-17, S-A spines 10-14. Pectoral axil 

 spines 0. 11-0.16, usually longer than longest fron- 

 tal spines. A short, fixed tribase spine im- 

 mediately above gill opening. D 16-18, A 16-18, P 

 19-22. Nasal tentacle with a pair of lateral open- 

 ings. No barbels or fleshy tentacles. Dorsal and 

 anal fins falcate (rounded in juveniles). Color pat- 

 tern dominated by small (ca. = to pupil) dark 

 spots dorsally and laterally. These often as- 

 sociated with the spine axils. A dark gular band 

 starting from below the eyes and continuing under 

 the chin, usually with a branch extending dorsally 

 between eye and gill opening. 



Descn'p^/o/;.— (35 specimens) D 16-18, A 16-18, the 

 first two or three rays unbranched; P 19-22. Head 

 width 0.25-0.30 (.v = 0.27; SD - 0.01), body width 



0.25-0.35 (.V = 0.30; SD = 0.02), peduncle length 

 0.16-0.22 (.V = 0.19; SD = 0.02), eye 0.05-0.10 

 (X = 0.08; SD = 0.01). Dorsal and anal fins falcate, 

 not rounded. Nasal tentacles with a pair of lateral 

 openings. 



S-D spines 13-17, S-A spines 10-14, about 12 

 spine rows over the dorsum between pectoral fin 

 bases, about 21 spine rows over the ventrum be- 

 tween pectoral fin bases. Four or five frontal 

 spines. Longest frontal spine 0.07-0.15 ix = 0.11; 

 SD =0.05), pectoral axil spines 0.11-0.16 

 ix = 0.14; SD = 0.01). Pectoral axil spines usually 

 the longest on the body, 0.61-1.03 ix = 0.78; 

 SD = 0. 1 1 ) in frontal spines. Spines long and slen- 

 der. Frontal, middorsal, and ventral spines of 

 about the same length. Pectoral axil spines and 

 those dorsolateral spines from over eye to over 

 pectoral fin among the longest on body (ca. 0.8 in 

 frontal spines). Spines on caudal peduncle short 

 (ca. 1.5 in frontal spines) and fixed due to a rather 

 long shaft extension (ca. 2 in shaft). Shaft exten- 

 sion on other spines reduced, never more than 159f 

 of the shaft length. Subdermal bases moderate in 

 extent, and, except for spines around fin bases and 

 caudal peduncle, always shorter than shaft. No 

 spines markedly reduced other than on caudal 

 peduncle; the latter spines generally arranged in 

 one or two bilateral pairs along the dorsolateral 

 edge of the peduncle. Approximately 40^^ (14 of 

 36) of the specimens examined also possess a 

 single dorsomedial spine on the caudal peduncle. 

 A short, fixed tribase spine immediately above the 

 gill opening and a second slightly posterior to it 

 above the pectoral base. Three short, flat spines 



Figure l.— Diodon eydouxii, 128 mm SL, central Pacific (NMFS H CHG 55-71) 



542 



