ceratobranchials 



epibranchials 



pharyngobranchials 



CDQ C=~> basibranchials 



hypobranchials 



Figure 285.— Diodon holocanthua: 

 dorsal view of branchial arches 

 (extended on lower side); lateral 

 (above) and medial (below, upside down) 

 views of hyoid arch; composite based 

 on several specimens 12.3-124 mm SL, 

 Gulf of Mexico and Caribbean. 



those species in which all of the spines have massive tri- 

 or quadriradiate bases and are nonerectile and Diodon 

 for those species in which at least some of the spines have 

 less massive and only biradiate bases and are erectile. 

 However, in the two most recent revisions of diodontid 

 systematics, three genera have been recognized by 

 Fraser-Brunner (1943) and Le Danois (1959), entirely on 

 the basis of the nasal apparatus and spines, and none of 

 the three genera are entirely comparable between the two 

 works. 



Fraser-Bruner ( 1943) recognized Diodon for those spe- 

 cies with two nostrils and with at least some of the spines 

 erectile (principally hystrix, holocanthus, jaculiferus, 



calori), Dicotylichthys for those with a bifid nasal tenta- 

 cle and with at least some of the spines erectile (princi- 

 pally nicthemerus, pilatus, punctulatus, and diuersi- 

 spinis), and Chilomycterus for those with two nostrils 

 (the division between which might be fragile and easily 

 broken) and with all of the spines three rooted and non- 

 erectile (numerous species). 



Two or three subgenera were recognized by Fraser- 

 Brunner (1943) in each of the three genera but these have 

 not been used by subsequent workers. The three subgen- 

 era of Diodon and Dicotylichthys have exactly the same 

 characters, one subgenus in each for those species all of 

 whose spines are two rooted and erectile and two sub- 



