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
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