CHAETODON AYA AND RELATED DEEP-LIVING BUTTERFLYFISHES: THEIR "ARIA TION, DISTRIBUTION AND SYNONYMY CARL L. HUBBS Scripps Institution of Oceanography University of California, San Diego La Jolla, California ABSTRACT The phyletic line of the Chaetodontidae here treated seems to comprise four species referable to Chaetodon (lalcifer. of the eastern Pacific, from islands off Baja California; aya, of the Gulf of Mexico and the South Atlantic coast of the United States; guyanensis, known from the Antilles and French Guiana; and marcellae, from tropical western Africa) plus the highly modified Prognathodes aculeatus, of the Antillean and Caribbean region, which parallels such Indo-Pacific genera as Forcipiger. Knowledge of this group has been increasing exponentially. All five species live at greater depths than are usually inhabited by chaetodontids. The known captures and observations of these species are tabulated. Their distribution, ecology, meristic variation, and other characters are treated. Seven of the 141 counts of principal caudal rays depart from the normal formula of 9 + 8 = 17: 4 specimens of C. aya and 3 of P. aculeatus have 8 + 8 = 16 rays, and 1 of the 3 counted specimens of C. guyanensis has 9 + 9 = 18 rays, which number is highly aberrant for any percomorph with a forked caudal fin. In having only 4 soft-rays in one pelvic fin, one specimen among 155 counted deviates from the almost invariable pelvic-ray formula, I, 5, that characterizes almost all percomorphs with well-developed pelvics. Direct observations are added on the life ways of Prognathodes aculeatus and of Chaetodon falcifer. INTRODUCTION The group of deep-living chaetodont fishes herein discussed was first treated by Hubbs and Rechnitzer (1958), as an extension to their descrip- tion of Chaetodon falcifer, a new species from Guadalupe Island, in the warm-temperate eastern Pacific off Baja California, Mexico. Since that paper was written I have continued to gather information on this previously little-known group of butterflyfishes, with the generous and extensive aid of many colleagues, listed below under Acknowledgments. Since the first species of this group was described in 1860, knowledge of the series has increased exponentially, with a particularly rapid rise during the past few years. This expansion in knowledge, which reflects the increase in exploratory effort, first slow and lately rapid, can be visualized by graph- ing, for the period of an approximate century (1860 through 1962), the cumulative numbers known in each year of valid species, of nominal spe- cies, and of records (collections and scientific observations) (Figure 1). The recent increase would be still more spectacular, if total numbers of IContributions from the Scripps Institution of Oceanography, New Series. ]34 Bulletin of Marine Science of the Gulf and Caribbean [13(1) 9- r I I I 8- r I I I 80 7- r (/) I W I U , 70 ~ 6- ,---J (/) (/) PROGNATHOOES o I ACULEATUS a: I 60 o o"- 1 u a: ~- r' w w I a: 00 I I ~O :::;: I o"- ~ 4- C MARCELLAE a: Ir-----------------~ w W 00 > I C GUYANENSIS :::;: I ::> ~ 3- r-----.J NOMINAL SPECIES z ...J I w ::> I :::;: I > ::> CHAETOOON AYA >= u ~ ...J ::> :::;: ::> u C FALCIFER 1860 70 80 90 1900 10 20 30 40 ~O 1960 FIGURE 1. Increase in knowledge of the 5 species of chaetodontid fishes herein treated, from the discovery of 1 species in 1860 until 1962; expressed in terms of the cumulative number of valid species known, of nominal species described, and of number of published records. The disjunct column at the right shows the distribution by species of 87 records accumulated by 1962. The records are tallied in Table 6. One record each for C. aya (39a), C. guyanensis (41a) and two records (87 and 90) for P. aculeatus were received too late for inclusion on this figure. known specimens were graphed. A similar demonstration could be shown for many other groups, particularly for those representing species living at moderate to great depths, which are being so effectively collected by the OREGON and other exploratory fishing vessels. It is greatly to the credit of the officials concerned that the rich scientific harvests of the exploratory cruises are being exploited. The advancing knowledge of each of the five species of this group is documented by the chronologically tabulated list of collections (Table 6) and by an annotated synonymy, in which I have attempted to include all pertinent references. By oddly compounded coincidence each of the four Atlantic species was twice named, three of them within a one-year period. This species group was characterized, its relationships discussed, and the constituent species compared, by Hubbs and Rechnitzer (1958), by Durand (1960), and by Bauchot and Blanc (1961). The relationship of 1963] Hubbs: Chaetodon Aya and Related Butterflyfishes 135 Prognathodes aculeatus to this assemblage in Chaetodon rather than to the superficially similar Forcipiger was further noted by Randall (1961). ACKNOWLEDGMENTS As noted above, many colleagues, of various institutions, have greatly and generously assisted me by providing specimens and data for this study. Among these, in alphabetic order, are W. W. Anderson, U. S. Bureau of Commercial Fisheries Biological Laboratory, Brunswick, Georgia; M.-L. Bauchot and Maurice Blanc, Museum National d'Histoire Naturelle Paris; M. Boeseman, Rijksmuseum van Naturlijke Historie, Leiden; James E. Bohlke and Charles C. G. Chaplin, Academy of Natural Sciences of Philadelphia; Harvey R. Bullis, Jr., Pascagoula Fishery Station, U. S. Bureau of Commercial Fisheries; Jean Cadenat, Institut Fran~ais d'Afrique Noire; David K. Caldwell, formerly of U. S. Bureau of Commercial Fishe- ries Biological Laboratory, Brunswick, Georgia, now of Los Angeles County Museum; Daniel M. Cohen, U. S. Bureau of Commercial Fisheries Laboratory, U. S. National Museum; C. E. Dawson, formerly of Bears Bluff Laboratories, now of Gulf Coast Research Laboratory; Myvanwy Dick, Museum of Comparative Zoology, Harvard College; Jean Durand. Museum National d'Histoire Naturelle, Paris; Donald S. Erdman, Puerto Rico Departamento de Agricultura y Comercio; Henry A. Feddem, Marine Laboratory, University of Miami; Charles Guthrie, U.S.N.; J. J. Hoede- man, formerly of the Zoblogisch Museum, Amsterdam; Paul Klihsbauer, Naturhistorisches Museum Fischsammlung, Wien; Robert H. Kanazawa, U. S. National Museum; Gerrit Klay and Ingvar Kristensen, Caraibisch Marien-Biologisch Instituut, Cura~ao; Francesca LaMonte, American Mu- seum of Natural History; John B. Lewis, the Bellairs Research Institute of McGill University, Barbados: the late Conrad Limbaugh, Scripps Institu- tion of OceanolZraphy; G. Robert Lunz, Bears Bluff Laboratories; N. B. Marshall, British Museum (Natural History); Giles W. Mead, formerly of U. S. Bureau of Commercial Fisheries Laboratory, U. S. National Mu- seum, now of Museum of Comparative Zoology, Harvard College; G. F. Mees, formerly of Rijksmuseum van Naturlijke Historie, Leiden, now of Western Australian Museum; George C. Miller, U. S. Bureau of Commer- cial Fisheries Biological Laboratory, Brunswick, Georgia; Robert Rush Miller, University of Michigan Museum of Zoology; Max Poll, Koninklijk Museum voor Midden-Afrika, Tervuren, Belgium; Keith W. Radford, Scripps Institution of OceanolZraphy; John E. Randall, formerlv of Marine Laboratory, University of Miami. now of University of Puerto Rico; An- dreas B. Rechnitzer, formerly of Scripps Institution of Oceanography, now of Autonetics, Anaheim, California; C. Richard Robins, Marine Labora- tory, University of Miami; Richard H. Rosenblatt, Scripps Institution of Oceanography; Leonard P. Schultz, U. S. National Museum; Walter A. 136 Bulletin of Marine Science of the Gulf and Caribbean [ 13(1) Starck, 11, Marine Laboratory, University of Miami; James R. Stewart, Scripps Institution of Oceanography; Ethelwynn Trewavas, British Museum (Natural History); Robert L. Wisner, Scripps Institution of Oceanography; F. G. Wood, Jr., Marineland, Florida; Loren P. Woods, Chicago Natural History Museum; Jacques S. Zaneveld, formerly of Caraibisch Marien- Biologisch Instituut, Curac;ao, now of College of William and Mary. Others have supplied information on the lack of material in other institutions and on the apparent absence of Chaetodon falcifer on the Mexican mainland. Though it is difficult aT'\d rather unfair to select from this long list of names for special acknowledgment, I must say that Caldwell, Dawson, Mees, G. C. Miller, Randall, Starck, and Zaneveld have all abstained in my favor from publishing on the western Atlantic species; Mees in particular had a manuscript on Prognathodes aculeatus in preparation and anticipated me in the study of critical material at Leiden and London; Boeseman supplied extensive notes from Mees's manuscript. Robins, Randall, Starck, and particularly Zaneveld, made available ecological and life-color pates on P. aculeatus. Stewart collected Chaetodon falcifer at a second locality and made further observations on this species. Limbaugh, Rosenblatt, and others searched for it along the Baja California coast. Radford and Wisner assisted by making radiographs and in other laboratory operations. Randall and Robins offered valued suggestions on reading the manuscript. In gathering data for this paper in many museums, in studying material at La Jolla, and in preparing the manuscript, I again owe much to my good wife, Laura. This report represents one phase of a program supported by a grant from the National Science Foundation. MATERIAL During trips