UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN BIOLOGY JUL 1 y 15ev FIELDIANA Zoology Published by Field Museum of Natural History ^ Volume 58, No. 8 October 15 1971 A Redescription of Amphiprion nigripes Regan, a Valid Species of Anemonefish (Family Pomacentridae) from the Indian Ocean Gerald R. Allen Dept. of Zoology; University of Hawaii; Honolulu AND Bbrnice p. Bishop Museum AND Richard N. Mariscal Dept. of Biological Science, Florida State University, Tallahassee ABSTRACT Amphiprion nigripes Regan, usually considered a synonym of Amphiprion perideraion Bleeker, is shown to be a valid species of anemonefish. It is redescribed, illustrated, and compared with A. perideraion. Observations on the ecology and behavior of A. nigripes in the Maldive Islands are included. INTRODUCTION Amphiprion nigripes was described by C. Tate Regan in 1908 from a single specimen of 75 mm. total length collected at the Mal- dive Islands. In his short description he states that the species is closely allied to A. melanopus Bleeker and A. perideraion Bleeker, especially to the latter. Leonard P. Schultz revised the genus Am- phiprion in 1953, but neglected to list A. nigripes as either a valid species or synonym. Woods and Schultz (Schultz et al., 1960) in- clude it as a synonym of A. perideraion and under the remarks sec- tion of their paper they state: "Schultz examined the type of A. nigripes in the British Museum and found the pectoral fin to have Library of Congress Catalog Card Number: 78-165189 Publication 1136 93 TME LIBRARY OF TM MM 2 1972 5 1972 ;:i?^i^"««5* "5*'"«)!.?A,'iyil2!? 94 FIELDIANA: ZOOLOGY, VOLUME 58 19 rays, which number is 2 more than for western Pacific specimens of perideraion. Thus, A. nigripes may be a valid species close to A. perideraion." They conclude by stating that a series of specimens with distinct color patterns is needed to work out the relationship of these forms. As a result of a collection of fishes made at Male Atoll, Maldive Islands in 1964 by the junior author (Mariscal, 1966; 1967) and addi- tional collections from this same locale made by Loren P. Woods of Field Museum of Natural History in 1964, it has been ascertained that A. nigripes is indeed valid. A revision of the genus Amphiprion currently in progress by the senior author reveals that the closest relative of A. nigripes is A. perideraion, as Regan originally suggested. For the purposes of comparison, a table of certain counts of selected examples of A. perideraion (Table 1) and an illustration (fig. 1) of this species are included below. Abbreviations used in the text are as follows: BM (British Mu- seum) ; BPBM (Bernice P. Bishop Museum) ; CAS (California Acad- emy of Sciences); FMNH (Field Museum of Natural History); SU (Stanford University) ; USNM (U. S. National Museum). Amphiprion nigripes Regan. Figure 2. Amphiprion nigripes Regan, 1908, Trans. Linn. Soc. London, ser. 2, Zool., 12, p. 230, pi. 24, fig. 2. (type locality: Maldives) Amphiprion perideraion (in part) Woods and Schultz, 1960, U. S. Nat. Mus. Bull. 202, 2, p. 54. Diagnosis. — A species of Amphiprion with the following combina- tion of characters: standard length more than twice the greatest body depth; 18 or 19 pectoral rays; interorbital entirely scaled; pelvic and anal fins black; a single pale bar, 2 to 4 scales in width, behind the eye. Description. — Dorsal rays X, 17 or 18 (usually 17); anal rays II, 13 to 15 (usually 14); pectoral rays 18 or 19; scale rows from upper edge of gill opening to base of caudal rays 55 to 68 (usually 56 to 60) ; from base of dorsal fin to lateral line four to five (not including dorsal base sheath scales); from lateral line to origin of anal fin 20 to 22; tubed lateral line scales 33 to 45 (usually 38 to 42) ; predorsal scales 20 to 25 (usually about 22); spines in opercular series 30 to 51; pre- opercle spines 7 to 22; suborbital spines 8 to 27; teeth conical, about 40 to 45 in each jaw of adults; total gill rakers on first arch 17 to 21 (usually 18 or 19). Ct3 C CIS Pi a o >> o -tj o 95 96 FIELDIANA: ZOOLOGY, VOLUME 58 Depth of body 2.0 to 2.2; head 2.7 to 3.3; both in standard length. Snout 3.8 to 4.4; eye 3.0 to 3.8; interorbital width 3.5 to 4.2; depth of caudal peduncle 1.7 to 2.0; length of caudal peduncle 1.7 to 2.0; Fig. 2. Amphiprion nigripes, 73.5 mm. standard length, South Male Atoll, Maldive Islands (FMNH 74948). Photo by John E. Randall. length of pectoral fin 1.0 to 1.2; of pelvic fin 1.1 to 1.3; of longest (fourth or fifth) dorsal spine 2.5 to 3.0; of middle caudal rays 0.8 to 1.3; all in length of head. Angle of snout profile with lengthwise axis of body 50 to 54 degrees. Spines of dorsal fin low, gradually increasing in height to fourth or fifth spine; then gradually decreasing; caudal fin truncate to slightly emarginate; predorsal scales extend to an imaginary line connecting the anterior edge of the orbits. The spine counts of the head are variable, generally increasing in number with age. Color in alcohol: Head and side of body primarily brown with a slight reddish cast, grading to darker brown ventrally; breast pale brown; narrow (two to three scales wide) greyish bar behind the eye extending from mid-dorsal region to the lower margin of the sub- opercle; the bars of each side usually join dorsally, but there are occa- sional exceptions. Pelvic and anal fins black; all other fins tan and slightly reddish. The caudal peduncle usually lighter brown than the rest of the body. Live coloration: Head and body largely orange; snout pinkish; a single white bar behind the eye; dorsal fin and pectorals red-orange; caudal fin yellow-orange; pel vies and anal fin black. There is an ALLEN AND MARISCAL: ANEMONEFISH SPECIES 97 excellent color photo of this species in Eibl-Eibesfeldt (1965, pi. 9), erroneously referred to as Amphiprion melanopus. Comparisons. — On the basis of gross external morphology, A. nigripes belongs to the subgroup of Amphiprion containing A. akal- lopisos, A. perideraion, and an unnamed form from the Philippine Islands which will be described later by the senior author. All of these are slender forms whose depth is less than half the standard length. A. akallopisos usually has 19 soft dorsal rays compared to the usual 17 for nigripes. Also akallopisos lacks the head bar, a character which is shared by the undescribed Philippine species. In nigripes the head bar is always present. A. nigripes most closely resembles A. perideraion on the basis of morphology and color pattern, but differs from it in several respects (see Table 1). In addition to the characters listed in Table 1, note- worthy differences can be found in the shape of the teeth and in color pattern. A. nigripes has conical-shaped teeth while those of peride- raion are more or less incisiform. The pelvic and anal fins of nigripes are characteristically black and in perideraion they are pale tan. A. melanopus, which is confined to the New Guinea region, Great Barrier Reef, and islands of the western Pacific, was considered to be a close relative of A. nigripes by Regan (1908) and has subsequently been confused with this species by other workers. Important differ- ences between these two species can be found in body depth and color. The depth in the standard length for ten specimens of A. melanopus examined varied from 1.7-1.9, while the depth of A. ni- gripes is always in excess of 2.0. The pelvic and anal fins of these two species are usually black. However, in nigripes the black color is confined to these fins and the ventral portion of the body adjacent to them, while in melanopus the entire body is usually blackish. A. melanopus juveniles are usually dark colored and exhibit two to three white bars up to a size of at least 30 mm. standard length. A. nigripes juveniles are pale and have only one bar, just behind the eye. TABLE 1. — A comparison of soft fin-ray counts and number of vertical scale rows of Amphiprion nigripes and A. perideraion. Pectoral Dorsal rays rays Anal rays Vertical scale rows leT? 18 1? 16 17 18 I2T3 14 Ts <53 54 55 56 57 58 59 60^ A.nigripes 10 6 13 3 1 14 1 113 4 2 2 A. perideraion 1 14 1 12 4 4 12 4 3 1 1 98 FIELDIANA: ZOOLOGY, VOLUME 58 Field Observations. — Field observations of the anemonefish symbi- osis have been conducted by the junior author in the South Pacific at Tutuila Island, E. Samoa; Great Astrolabe Reef, Fiji Islands; Vanikoro Island, Santa Cruz Islands; Bougainville Island, Solomon Islands; New Britain Island, Territory of New Guinea; and at Green Island on the Great Barrier Reef, N. Queensland, Australia. In the Indian Ocean, field studies were conducted off the coast of Kenya, East Africa; at Mahe Island, Seychelles Islands; at Funidu and Hulele Islands, Male Atoll, Maldive Islands, and at Pipidon and Pipilek (Phi Phi Islands) off Phuket, W. Thailand. Based on these observations and collections and the literature, it is obvious that some species of Amphiprion, such as A. percula (Lacapede) and A. xanthurus, have a wide distribution throughout the South Pacific and Indian Oceans. Others, such as A. akallopisos, are common throughout the Indian Ocean while still other species appear to be more or less restricted to the Pacific. Thus, it came as a surprise to find Amphiprion nigripes apparently restricted to the Maldive Is- lands in the Indian Ocean, although another widely distributed Amphiprion (e.g., A. xanthurus) was also common here. At Funidu Island, A. nigripes was the most common species of Amphiprion present. It was found exclusively in the Indo-Pacific host anemone Radianihus ritteri Kwietniewski. A. xanthurus (with only a single exception) was restricted to the other common giant anemone present, Stoichadis giganteum Forsskal. A. nigripes never wanders far from its anemone host and is very aggressive toward other species of fishes which enter the immediate vicinity. However, up to eight A. nigripes, of variable size, may be found inhabiting a a single anemone. In other cases, the R. ritteri anemones occurred in clusters and a number of individual A. nigripes freely moved between several neighboring anemones. In the several hundred specimens of A. nigripes either observed or collected in the field by the junior author, the color and banding pattern was remarkably uniform. The pel vies and anal fin were black in the larger specimens. The juveniles, however, appear to lack the black fins initially. Changes in color and pattern with growth were followed over a period of about one month in the shipboard aquarium for a single juvenile A. nigripes. During this time the fish nearly doubled in size (a standard length of 16.5 mm. when preserved). When this fish was first captured with the larger fish and anemone shown in Figure 3, the pelvic fins were a bright yellow-orange as were the other i ALLEN AND MARISCAL: ANEMONEFISH SPECIES 99 Fig. 3. Underwater flash photograph of Amphiprion nigripes with its Radian- thus ritteri anemone. Several Dascyllus trimaculatus were also inhabiting this anemone along with the A. nigripes. Photograph taken by Mariscal at Funidu Island, Male Atoll, Maldives on November 6, 1964. fins. However, about two w^eeks after capture the pelvic fins had begun to acquire a dusky black color, as did the abdominal region. This latter phenomenon appeared to be due to the visceral perito- neum taking on a black pigmentation and seemed to be correlated with the acquisition of the black fin color. Initially, the black chro- matophores of the fins were concentrated between the fin rays and then gradually spread out over the fins. In this particular case, the black color of the anal fin was acquired after that of the pelvics since no anal fin color change was observed by the time the young fish was preserved. The narrow, white head bar also changed with growth during this period. When collected, the lateral portions of the bars did not t 100 FIELDIANA: ZOOLOGY, VOLUME 58 meet dorsally, but over a period of the next three weeks the two sides of the bars gradually grew toward each other until the juncture was complete. Apparently, this union sometimes fails as relatively large adults were both collected and observed with a noticeable gap in this bar dorsally. During the final week of observations, the dark- ening of the pelvic fins and the joining of the white bar were proceed- ing rapidly enough so that a slight daily change could be detected. It was of interest to note that at the same time the above changes in color, pattern, and size were occurring in the small A. nigripes, there also seemed to be an increased awareness of the small fish by the larger A. nigripes in the same anemone (fig. 3). This was evi- denced by the increased frequency of chasing of the smaller fish and might have been triggered by the juvenile fish's aforementioned ac- quisition of the adult characteristics. During this time the young fish became increasingly territorial toward the species of Dascyllus in the same aquarium (D. trimaculatus and D. aruanus) . Observations of the behavior of adult A. nigripes have been re- ported elsewhere (Mariscal, 1966, 1967, 1970a, in press). Material examined (Lengths are standard length). — A. nigripes, 18 specimens, 28.4-78.6 mm. Maldive Islands; Indian Ocean; BM 1908.3.23.101, 1 (type), 57.4 mm.; FMNH 74948, 9, 37.2-78.6 mm.; FMNH 74548, 2, 28.4-33.4 mm.; FMNH 74547, 2, 47.0-54.0 mm.; FMNH 74950, 2, 45.9-54.0 mm.; Mariscal collection, 1, 16.5 mm. A. perideraion, 30 specimens, 29.5-70.8 mm. Gulf of Thailand — Three lots of uncatalogued material at the CAS, 25 specimens 29.5- 70.8 mm. Palau— BPBM 6809, 4, 32.0-70.0 mm. Singapore— FMNH 74947, 1, 55.0 mm. A. melanopus, ten specimens, 48.6- 87.5 mm. Caroline and Marianas Islands — Four lots of uncatalogued material at the CAS, four specimens, 61.0-87.5 mm. New Cale- donia—USNM 197683, 1, 48.6 mm. New Guinea— SU 28651, 1, 55.4 mm. New Hebrides— USNM 197238, 1, 65.5 mm. Marshall Islands— BPBM 6380, 2, 58.0-69.5 mm. Queensland— USNM 204282, 1, 73.5 mm. Acknowledgments We would like to express our thanks to Dr. Donald P. Abbott, Hopkins Marine Station, Stanford University, who served as chief scientist of the 1964 Te Vega expedition and made the junior author's participation in this cruise possible. The National Science Founda- ¥ ALLEN AND MARISCAL: ANEMONEFISH SPECIES 101 tion Grant G17465 provided the funds necessary to fit out and op- erate the R/V Te Vega. The senior author acknowledges Loren P. Woods of Field Museum of Natural History for his hospitality dur- ing a study visit to that institution during the summer of 1969 and for the loan of specimens of A. nigripes collected by Mr. Woods in the Maldive Islands. Thanks are also due Dr. William Eschmeyer of the California Academy of Sciences for his assistance while the senior author visited that institution in May and August, 1969. Dr. Eschmeyer also examined the type specimen of A. nigripes at the British Museum for the authors. I REFERENCES ElBL-ElBESFELDT, I. 1965. Land of a Thousand Atolls. MacGibbon and Kee, London. 195 pp. Mariscal, R. N. 1966. A field and experimental study of the symbiotic association of fishes and sea anemones. PhD. dissertation, University of California, Berkeley. Univer- sity Microfilms, Ann Arbor. 262 pp. 1967. A field and experimental study of the symbiotic association of fishes and sea anemones. Diss. Abst., 28(1), p. 388-B. 1970a. A field and laboratory study of the symbiotic behavior of fishes and sea anemones from the tropical Indo-Pacific. Univ. Calif. Pubis. Zool., 91, pp. 1-33, 4 pi. In press. The symbiotic behavior between fishes and sea anemones. In H. E. Winn and B. OUa, eds.. Behavior of Marine Animals — Recent Advances, Plenum Publishing Corp., New York. Regan, C. T. 1908. Report on the marine fishes collected by Mr. J. Stanley Gardiner in the Indian Ocean. Trans. Linn. Soc. London, 12, pp. 217-255, pis. 28-32. SCHULTZ, L. P. 1953. Review of the Indo-Pacific anemonefishes, genus Amphiprion, with descriptions of two new species. Proc. U. S. Nat. Mus., 103(3323), pp. 187- 201, pis. 9-10. ScHULTz, L. p., W. M. Chapman, E. A. Lachner, and L. P. Woods. 1960. Fishes of the Marshall and Marianas Islands. U. S. Nat. Mus. Bull., 202, 2, pp. i-xi, 1-438, pis. 75-123. I i ^!^ SiilHmSffi^^^^^H^^ UNIVERSITY OF ILLINOIS-URBANA 590. 5FI C001 FIELDIANA, ZOOLOGY$CHGO 55-58,61 1968-72 3 0112 009379840