Chlorurus perspicillatus x C. sordidus, a hybrid parrotfish from the Hawaiian Islands

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1 aqua, Journal of Ichthyology and Aquatic Biology Chlorurus perspicillatus x C. sordidus, a hybrid parrotfish from the Hawaiian Islands Bishop Museum, 1525 Bernice St., Honolulu, HI , USA Accepted: Keywords Marine fishes, hybrids, Scaridae, Chlorurus, Hawai`i Abstract The hybrid of the Hawaiian scarid fishes Chlorurus perspicillatus x C. sordidus is documented from evidence of intermediate colour pattern, cheek scale count, and DNA analysis. Zusammenfassung Dokumentiert wird ein Hybride der hawaiianischen Papageifische (Scaridae) von Chlorurus perspicillatus x C. sordidus. Für die Hybridbildung aus den genannten Arten sprechen das dazwischen liegende Farbmuster, die Zahl der Wangenschuppen und eine DNA- Analyse. Résumé Est documenté ici l hybride de poissons-perroquets Chlorurus perspicillatus x C. sordius sur base des caractéristiques évidentes du patron de coloration intermédiaire, du nombre d écailles sur les joues et de l analyse ADN. Sommario Si documenta l esistenza di una forma ibrida di due pesci pappagallo delle Isole Hawaii Chlorurus perspicillatus x C. sordidus desunta dalla colorazione intermedia, dal conteggio delle scaglie sulla guancia e dall analisi del DNA. The use of scuba and the ichthyocide rotenone during the last 55 years has resulted in large collections of marine fishes, especially from tropical and subtropical seas. Improved photography has provided accurate, lasting images of the colour of these fishes. Molecular technology has aided our ability to discriminate closely related species of fishes. As a result of our increased taxonomic knowledge of fishes, there has been a sharp increase in the discovery of hybrids in recent years, as noted by Schwartz (2001). Among reef fish families, the most hybrids have been reported for the butterflyfishes (Chaetodontidae) and the angelfishes (Pomacanthidae), no doubt due in part to their distinctive colour patterns and their popularity with snorkelers, divers, and aquarists. Schwartz listed the wrasse family Labridae as the third highest for reef fishes in the number of known hybrids. Walsh and Randall (2004) reviewed recent examples of hybrids of the labrid genus Thalassoma, including an intergeneric hybrid with Gomphosus. There seem to be no records of hybrids in the related parrotfish family Scaridae. Liao et al. (2001) published a review of the scarid fishes of Taiwan. Included was a photograph of one specimen of a terminal male that is intermediate in colour pattern to Scarus frenatus and S. prasiognathos. However, their molecular data failed to show that the specimen was in either sister group of S. frenatus or S. prasiognathos. In January 1998 Ken Lee collected a parrotfish 405 mm in standard length while scuba diving at night in 10 m off Sandy Beach, O ahu (Fig. 1). He was unable to identify the fish, so he brought it to the author at the Bishop Museum, who was also perplexed. The size, general morphology, and colour pattern of the body suggested the terminal male of the Spectacled Parrotfish, Chlorurus perspicillatus (Steindachner), endemic to the Hawaiian Islands. However, the bizarre reticular pattern of the head is unlike that of any scarid fish in Hawai`i. The specimen was deposited at the Bishop Museum as BPBM It was decided that the specimen was just a mutant colour morph of Chlorurus perspicillatus. Figure 2 shows the terminal-phase male of this species. In order to get confirmation of this, a tissue sample was taken from Lee s fish, as well as samples from fresh specimens of C. perspicillatus. These samples were sent to James Nelson, then of the National University of Singapore, for DNA comparison. After his analysis, he replied that the specimen was either a hybrid or an undescribed species. Neither option seemed feasible. There are only seven species of parrotfishes in the Hawaiian Islands region, and because scarids are shallow-water fishes and the islands are heavily fished, the chance of finding a new species of this family in Hawai`i is extremely remote. There is only one other Hawaiian species of the genus Chlorurus, the Bullethead Parrotfish, 39

2 Chlorurus perspicillatus x C. sordidus, a hybrid parrotfish from the Hawaiian Islands C. sordidus (Forskål) (terminal phase male shown as Fig. 3). It is a smaller fish and would not seem a likely candidate for spawning with C. perspicillatus (although contiguous spawning of two species could result in the sperm of one fertilizing the ova of the other). More important, there is no obvious suggestion of the colour pattern of sordidus in the puzzling specimen. It was then concluded that Dr. Nelson s results were equivocal. However, underwater photographs of two different terminal males of an unusual parrotfish in Hanauma Bay, O ahu (Figs. 4 and 5) were later provided by Fig. 1. Chlorurus perspicillatus x C. sordidus, O ahu. BPBM 37906, 405 mm SL. Photo by J. Randall. Fig. 2. TP male of Chlorurus perspicillatus, O ahu. Photo by J. Randall. 40

3 John P. Hoover. The two fish could not be collected because the bay is a reserve. The photographs show an amalgamation of colour of the two species. Note that the body and caudal fin coloration is like that of C. perspicillatus, while the head colour pattern, including the blue-green dental plates, is more like that of sordidus. These two photographs therefore seem to confirm the hybrid option of Nelson s DNA comparison. Because the specimen of Figure 1 is so similar to C. perspicillatus, it may be an F2 hybrid, the result of interbreeding of the F1 hybrid (perspicillatus x sordidus) with perspicillatus. Fig. 3. TP male of Chlorurus sordidus, Maui. Photo by J. Randall. Fig. 4. Chlorurus perspicillatus x C. sordidus, O ahu. Photo by J. Hoover. 41

4 Chlorurus perspicillatus x C. sordidus, a hybrid parrotfish from the Hawaiian Islands In January 2005 Kevin F. Sakuda speared a second specimen of the terminal male phase of the hybrid, 343 mm in standard length, at Moku Manu, O ahu and presented it to the Bishop Museum (now catalogued as BPBM 39629). Its photograph is shown as Figure 6. A useful diagnostic feature to separate specimens of Chlorurus perspicillatus and C. sordidus is the number of scales in the second (lower) row on the cheek. Schultz (1958: table 3) recorded 0-3 scales for Chlorurus perspicillatus and 5-8 for C. sordidus. The two hybrid specimens, 343 and 405 mm SL, are much larger than the largest C. sordidus (largest Bishop Fig. 5. Chlorurus perspicillatus x C. sordidus, O ahu. Photo by J. Hoover. Fig. 6. Chlorurus perspicillatus x C. sordidus, O ahu, BPBM 39629, 343 mm SL. Photo by J. Randall. 42

5 Museum specimen of sordidus, 300 mm SL; terminal phase males can be less than 200 mm SL). The size of the two hybrid specimens favors perspicillatus, but the number of scales in the second row on the cheek, 5-7, falls in the count for sordidus. A Bishop Museum specimen of a parrotfish (BPBM 4751, 330 mm SL) collected in the 1920 s from the Honolulu market was initially labelled Scarus troschelii Bleeker. This was puzzling because the species is otherwise known only from the Indo-Malayan region (type locality, Java). No photograph or colour notes were taken of the specimen, which is now uniform museum brown. It was reidentified a few years ago as Chlourus sordidus, but with a question mark, because it measures 330 mm SL, hence larger than any known specimen of sordidus. It has now been identified as an initial phase of the hybrid of C. perspicillatus and C. sordidus. Its size favors C. perspicillatus, but the number of cheek scales in the second row, 6 on one side and 8 on the other, fits the count of C. sordidus. Acknowledgements Thanks are due Ken Lee and Kevin Sakuda for donating the hybrid specimen that each collected to the Bishop Museum, to John Hoover for his two photographs of the F1 hybrid, and to James Nelson for his analysis of DNA. References Liao, Y.-C., Chen, L.-S., Shao, K.-T. & I-S. Chen A review of the parrotfishes (Perciformes: Scaridae) of Taiwan with descriptions of four new records and one doubtful species. Zoological Studies, 43 (3): Schultz, L. P Review of the parrotfishes family Scaridae. United States National Museum Bulletin, 214: v pp. Schwartz, F. J Freshwater and marine fish family hybrids: a worldwide changing scene revealed by the scientific literature. Journal of the Elisha Mitchell Scientific Society, 117 (1): Walsh, F. M. & J. E. Randall Thalassoma jansenii x T. quinquevittatum and T. nigrofasciatum x T. quinquevittatum, hybrid labrid fishes from Indonesia and the Coral Sea. aqua, Journal of Ichthyology and Aquatic Biology, 9 (2): ********************************************************************************************************************************* ERRATA aqua 9 (3): Ninety-one new records of fishes from the Marshall Islands by, Robert F. Myers, Michael N. Trevor, Scott R. and Jeanette L. Johnson, Satoshi Yoshii and Brian D. Greene. P. 120: Fig. 17, change from video by J. L. Johnson to: Photo by M. N. Trevor. P. 127: reverse the captions for Figs. 49 and