SYSTEMATICS AND ZOOGEOGRAPHY OF THE PORCUPINEFISHES 



(DIODON, DIODONTIDAE, TETRAODONTIFORMES), WITH 



COMMENTS ON EGG AND LARVAL DEVELOPMENT^ 



Jeffrey M. Leis^ 



ABSTRACT 



The porcupinefish genu.s Diodon is composed of five species: D. hystrix Linnaeus and D. eydouxii 

 Brissout de Bameville are closely related species, each of which has a relatively elongate body, spines 

 on the caudal peduncle, and high dorsal and anal fin ray counts; D. holocanthus Linnaeus and D. 

 Uturosus Shaw form a second species pair, each of which has a round body, no caudal peduncle spines, 

 and moderate dorsal and anal fin ray counts; D. nicthemerus Cuvier is a round-bodied species but 

 differs from D. holocanthus and D. Uturosus in meristic characters and spination. 



Diodon hystrix. D. holocanthus. and D. eydouxii are distributed circumtropically. The Atlantic 

 population of D. holocanthus has diverged from the Indo-Pacific (including eastern Pacific) popula- 

 tions. Diodon eydouxii is pelagic, and both D. hystrix and D. holocanthus have pelagic juvenile stages. 

 Diodon Uturosus is found in the Indo-West Pacific, and D. nicthemerus is limited to Tasmania and 

 southern Australia. It is not known whether the latter species have pelagic stages. 



The egg and larval stages of D. hystrix and D. holocanthus (the latter identified by rearing) are 

 similar. The pelagic eggs are 1.6-2.1 mm in diameter and hatch in about 5 days at 25°C. The larvae 

 metamorphose to spiny juveniles at ca. 4 mm in about 3 wk. Both species have pelagic juvenile stages of 

 long duration: D. hystrix remains pelagic to ca. 200 mm standard length, thus providing ample time for 

 dispersal. Eggs and larvae of the other species are unknown. 



The identities of the species of the genus Diodon 

 have been confused since the time of Linnaeus. 

 The most recent description of a valid "new" 

 species was in 1846, but, unfortunately, time has 

 done little to clarify the situation. Twenty-eight 

 nominal species attributable to Diodon have been 

 described since 1758, and most contemporary au- 

 thors recognize two or three species. However, Le 

 Danois (1959), in the only recent review of the 

 genus as a whole, recognized six species. 



The present study grew out of attempts to iden- 

 tify juvenile Diodon that resulted from rearing of 

 pelagic eggs taken in Kaneohe Bay, Oahu, Hawaii 

 (Watson and Leis 1974). These juveniles could not 

 be identified using existing keys. While current 

 literature recognized only two species of Diodon in 

 Hawaiian waters, examination of museum speci- 

 mens revealed that three were present there. This 

 discovery, together with the encouragement of 

 J. E. Randall of the Bernice P. Bishop Museum, led 

 to the present study clarifying the identities of all 

 of the species of Diodon and the description of their 



'Hawaii Institute of Marine Biology Contribution No. 548. 



^Department of Oceanography, and Hawaii Institute of 

 Marine Biology, University of Hawaii, Kaneohe, Hawaii; pres- 

 ent address: Marine Ecological Consultants, 533 Stevens Av- 

 enue, Solana Beach, CA 92075. 



Manuscript accepted December 1977. 

 FISHERY BULLETIN: VOL. 76, NO. 3, 1978. 



development. An attempt was made to obtain in- 

 formation on existing type-specimens and this, 

 along with the examination of a large number of 

 specimens, has led to the conclusion that the genus 

 is composed of five species, three of which are dis- 

 tributed circumtropically. Further, it is shown 

 that the present taxonomic confusion is attributa- 

 ble to inadequate original descriptions, reliance 

 on poor characters for differentiation, the close 

 similarity of several of the species, and unusual 

 aspects of the life histories of the species of Diodon . 

 All of the nominal species could be distinguished 

 with some certainty with two exceptions: the type 

 of Diodon echinii.s Rafinesque 1810 could not be 

 located and the original description provides no 

 clue to its identification; the holotype of Trichocy- 

 clus ennaceus Giinther 1870 (BMHN 1976.2.23.1) 

 is a small fish in especially poor condition, giving 

 the appearance of having been obtained from a 

 stomach of some predator, and, while it is cer- 

 tainly a Diodon, more specific identification could 

 not be made. Diodon dussumieri Bibron (see Le 

 Danois 1959, 1961) is a nomen nudum, but exami- 

 nation of the "type" (MNHN 1306) by J. E. Randall 

 of the Bernice P. Bishop Museum indicates that Le 

 Danois was correct in placing D. dussumieri in 

 synonomy with D. holocanthus. 



535 



