Japanese Journal of Ichthyology 魚 類 学 雑 誌 Vol.36, No.4 1990 36巻4号 1990年

Social and Reproductive Behavior of Chaetodontoplus mesoleucus (Pomacanthidae) at Bantayan Island, Philippines, with Notes on Pomacanthid Relationships

Jack T. Moyer (ReceivedMarch 2, 1989)

Abstract Chaetodontoplus mesoleucus occurs at Bantayan Island in a habitat of small patches of mixed scleractinian and alcyonacean corals of low diversity and simple structure. Male-female pairs were predominant, and the sex-ratio showed only a slight skew towards females. However, the presence of single male, two-female social groups demonstrates that the species is polygamous. Small size of social groups is attributed to a preference for a habitat lacking structural complexity. The species did not occur on complex coral reefs. Social and spawning behavior are nearly iden- tical to that of most pomacanthids for which data are available, and although sex-change was not demonstrated, size-related dominance hierarchies and close phylogenetic relationships to sex-changing pomacanthids suggest protogynous hermaphroditism in this species. Behaviorally, C. mesoleucus appears quite similar to a large group of species proposed herein to represent a generalized pomacanthid behavioral type. Divergences from this generalized type by members of Genicanthus, eastern Pacific Holacanthus, and western Atlantic Pomacanthus are discussed. Evidence is given to suggest the phylogenetic derivation of the subgenus Centropyge (genus Centropyge) from an ancestor of the subgenus Xiphipops type. Color dimorphism and "rendezvous sites" are briefly discussed.

Marine angelfishes (Pomacanthidae) are among (reviewed by Moyer, 1987), it is essential to the most colorful and popular fishes in the in- examine representatives from Chaetodontoplus and ternational marine aquarium trade, yet as late as Apolemichthys before serious attempts can be 1975 virtually nothing was known about their made to unravel the complex interrelationships social organization and reproductive behavior within the family and thus better comprehend the (Burgess and Axelrod, 1972; Ehrlich, 1975). The evolutionary biology of pomacanthid reproduc- past decade has brought a wealth of data on tion. In this paper I provide information on pomacanthid social and reproductive biology, and social organization and spawning behavior of by 1987 information had been published on 30 Chaetodontoplus mesoleucus (Bloch) as a pre- pomacanthid species representing five genera liminary attempt to fill in the remaining gaps. (Table 2) (reviewed by Moyer, 1987). Social This is followed by a discussion of pomacanthid organization in the remaining genera in the family, relationships. Chaetodontoplus and Apolemichthys, is known

only from passing references (e.g., Moyer and Methods and materials Nakazono, 1978) and spawning behavior remains unreported. The study site. The site selected for this study Protogynous hermaphroditism has been reported was located near Suwangan Point, at the south- in three genera: Centropyge, Genicanthus, and western tip of Bantayan Island (11•‹09'N, 123•‹ Holacanthus (Table 2). Close similarities in 44'E), in the central Visayan Islands, Philippines. documented pomacanthid reproductive biology The substratum at the study site consisted of a

and in phylogenetic relationships have led some gradual sand slope which extended from the authors to assume protogynous hermaphroditism shore for about 1,000m southward to a depth of to be universal in the family (e.g., Neudecker and about 40m before dropping in a steep slope to Lobel, 1982). Although increasing knowledge depths over 100m. About 400m of this slope of the reproductive ecology of a variety of poma- are exposed to the atmosphere during spring neap canthid species seems to support this assumption tides. Areas of coral rubble and pavement and

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patches of living scleractinian and alcyonacean observed in 28h of observations, a single C.

corals are scattered sporadically over the sand vrolicki.

subtidally, however the paucity of coral reef Social groups consisted of a single territorial

fishes was conspicuous. male and one to two females, with the sex ratio

Methods of observations. Observations were only slightly skewed towards females (15males,

made by snorkeling at depths of 2-10m (approxi- 20 females) (Table 1). Of fifteen social groups mate neap tide depths). Approximately 1,500m under observation, ten were composed of male/

of slope at such depths were surveyed, from female pairs (Table 1). Multifemale groups were

Suwangan Point eastward. Due to logistical found only in relatively large patches of corals problems, daily observations were impossible, (Table 1: Groups 2, 5, 6), in situations where two however, attempts were made to survey study small coral patches were in close proximity populations at different times of day during a (Group 7), or when large and small coral patches variety of lunar and tidal conditions during the were in close proximity (Group 12). In all social period from November 1987 to January 1988. groups the single male was larger than any females Emphasis was placed on the crepuscular spawning in the group. A size difference between females time. Logistics also prohibited the collection of in two-female groups was also detected in all gonads for histological examination. Conse- examples. quently, the information reported herein must be The sizes of male territories were influenced by considered as preliminary. Scientific nomen- the amount of coral substratum available. Male clature follows Allen (1979). No.12 (Table 1) defended a particularly large

territory that encompassed two patches of corals Results and an isolated boulder where spawnings were initiated. This territory covered an area of

Social organization, sex ratio and territoriality. approximately 30m•~25m. In contrast, the

The dominant pomacanthid species at the study territory of Male No.4 was limited to one small site was Chaetodontoplus mesoleucus. Nearly coral patch of about 6m•~10m (Table 1). every relatively diverse patch of living corals sup- A major effort was made to determine whether ported a small population of this species. In or not "bachelor males" moved between social contrast, only one individual of the normally groups or remained cryptically within or near ubiquitous pomacanthid genus Centropyge was particular groups (see Moyer and Zaiser, 1984; Moyer, 1987). No bachelor males were identi-

Table 1. Social group composition of Chaeto- fied; however, on one occasion Male No.12 was dontoplus mesoleucus at Bantayan Island ,•@ observed invading the territory of Male No.13. Philippines. Aggressive interactions. Male-male aggression:

Intraspecific aggression between males of C.

mesoleucus was minimal. Male No.5 chased

Male No.6 from the periphery of his territory on

two occasions. In both cases, the smaller Male

No.6 fled immediately to the interior of his ter-

ritory and was not pursued. On one occasion,

just prior to the crepuscular spawning time, Male No.12 invaded about 5m into the territory of

Male No.13, where he encountered the home

male. A long, broadside chase followed. The

two individuals, with Male No.13 about a head-

length in front, raced nearly side-by-side, two

meters apart, dorsal, anal, and pelvic fins ex-

tended, for about 30m over bare sand and away

from their respective territories. Simultaneously,

both fish abandoned the chase and swam rapidly

back to their territories.

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Female-female aggression: Aggressive interac- briefly below: rushing and circling, soaring, tions between females were even less common mutual soaring, nuzzling, spawning, and after- than between males. My only observation of such chase. competition was on 4 February, when the largest a. Rushing and circling: This action is dis- female in the two female Group 12 rushed and played by a dominant fish to a subordinate, usual- circled (see "Motor Patterns," below) the smaller ly directed by the male towards a female in the female near the spawning rock shortly after group. Occasionally a dominant female will rush sunset. The smaller female fled, but soon re- and circle the smaller female. Rushing and turned to spawn. circling in Chaetodontoplus mesoleucus is identical Male-female aggression: Males invariably in function and form to that illustrated for rushed and circled females when their paths Centropyge interruptus by Moyer and Nakazono crossed while foraging throughout the day. On (1978). It is displayed whenever the paths of three occasions females fled such encounters and dominant and subordinate fish cross throughout were chased by males. Aggression was never the day, but increases dramatically in frequency observed during intervals when the male and in male-female interactions as the spawning time female foraged together in midday. However, nears. It is thus considered a component of the rushing and circling of females by males com- spawning sequence. menced and increased dramatically in frequency b. Soaring: Performed by the male with all as sunset neared (see "Motor Patterns," below). fins extended, this conspicuous display is used Interspecific aggression: Males of C. meso- only during the spawning period and in close leucus were frequently observed chasing the fol- proximity to a female. It is never seen prior to lowing four species of reef fishes during the the crepuscular spawning time. In C. mesoleucus, crepuscular spawning period: Choerodon anchor- the male performs this display in an upright ago (Labridae), Halichoeres trimaculatus (Lab- position. ridae), Abudefduf vaigiensis (Pomacentridae) and c. Mutual soaring: The female ceases for-

Amblyglyphidodon curacao (Pomacentridae). These aging at the approach of the male, rises 1.5-2m four species were never observed being chased in the water column in an upright position with prior to the crepuscular spawning period, and it all fins fully extended. Spawning follows within is assumed that they represent potential gamete a few minutes. predators. d. Nuzzling: The male places his snout

Courtship and spawning. Males and females against the abdomen of the female, near the vent. forage either solitarily or in male-female pairs Both fish rise vertically in this position for about throughout most of the day, with a minimum of two meters, suddenly spawning. social interaction. As sunset approaches, the e. Spawning: The male rotates his body 90•‹ male begins to interact more frequently with the to the right on the long axis, ejects sperm simul- female(s) in his group. Intensive courtship first taneously with the spawning of the female, and begins about one hour before sunset in the form leads his mate in a vertical dash to the substratum. of the "soaring" display (see below). Females f. After-chase: Directly after the post-spawn- continue to forage, showing little interest in male ing downward dash, the male chases the departing courtship activities until they are ready to spawn, female for 2-3m before foraging, searching for at which time they swim directly and rapidly to a another female, or taking shelter. "rendezvous site" (see below) where they initiate Rendezvous sites. In five social groups where spawning by responding to the male with "mutual courtship was witnessed three times or more, soaring." Eleven spawnings were observed rang- males and females commenced courtship activities ing from 9min before to 7min after sunset. at the same specific topographical feature on all

Motor patterns associated with spawning. occasions. These "rendezvous sites" (Moyer and

Motor patterns used in the spawning behavior of Zaiser, 1981) included a conspicuous Acropora

Chaetodontoplus mesoleucus are nearly idential colony (Table 1: Group 1), a large boulder of to those described and illustrated by Moyer and dead coral (Groups 2, 5, and 12), and a large soft

Nakazono (1978) for Centropyge interruptus. coral (Group 4). In all cases, males and females

The following six motor patterns are described began courtship at the rendezvous site, but moved

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elsewhere to spawn. For example, the spawning with C. mesoleucus at Bantayan Island. This is site for Group 12 was at a boulder some 30m tempting speculation, because C. mesoleucus was from the dead coral rendezvous site, across a not found to occur in a complex coral environ- patch of bare sand. ment, seeming to prefer a habitat of low diversity and simple structure, with the resulting low population density and only a slight female bias Discussion in sex ratio. However, this may not always be Social organization, sex ratio, and habitat. the case. My brief observations of the mono- Chaetodontoplus mesoleucus at Bantayan Island chromatic Chaetodontoplus personifer at Wistari most frequently occurs in male-female pairs. The Reef, on the Great Barrier R eef, Australia, sug- fact that single male social groups of three in- gested a situation very similar to Centropyge spp., dividuals also occur regularly, though less fre- i.e. a habitat of complex coral structure and the quently than pairs, indicates that C. mesoleucus presence of single male social groups with 3-4 is polygamous and that male-female pairs should females. Sufficient data are not yet available on be considered as "facultative monogamy." The the social organization of the monochromatic C. habitat at the study site consisted of a flat, mono- mesoleucus to permit broad generalizations; how- tonous substratum of predominantly soft sand ever, at Bantayan Island, C. mesoleucus social with sporadically scattered patches of mixed stony groups appear to exist with only minimal male- and soft corals; however, coral cover was not male competition, i.e. selective pressures for extensive and lacked complexity. Shelter sites sexual dichromatism appear minimal. were scarce and fish populations were not large. Is Chaetodontoplus mesoleucus protogynous? The small size and simplicity of coral patches ap- Observations of natural sex change in pomacan- parently restrict the size of C. mesoleucus social thids are scarce, even in field studies of long groups to pairs and small groups of three. Multi- duration (e.g., Aldenhoven, 1984; Moyer and female groups were found only within the com- Nakazono, 1978; Moyer and Zaiser, 1984). No paratively larger coral patches. Moyer and direct proof of hermaphroditism was obtained in Nakazono (1978) reported a similar situation for this study; however, some indirect lines of evidence the pomacanthid Centropyge interruptus at Miyake- point to typical pomacanthid protogyny. Males jima, Japan. That species was found to occur in are invariably larger than and dominant over pairs over a flat, monotonous substratum of females within social groups, and social groups relative simplicity. However, in fractured, com- larger than male-female pairs are always size- plex habitats, single male social groups of from dominance hierarchies. Motor patterns, habitat 3-6 individuals were the norm. Although details utilization, temporal reproductive cycles, social are lacking, Lobel's (1978) study of Centropyge behavior, etc., are very nearly identical to most potteri at Hawaii suggests a similar situation. other substratum-oriented pomacanthids (see Thus, the sex ratio of C. mesoleucus at Bantayan below). Further studies will almost certainly Island, where only a slight skew towards females disclose protogyny in Chaetodontoplus. was recognized, appears to result from habitat In situations such as that described from restrictions on population size. It is noteworthy Chaetodontoplus mesoleucus at Bantayan Island, that the species was never observed in careful however, sex change would occur infrequently. censuses on complex, rich, diverse coral reefs Aldenhoven (1986), writing about Centropyge at the island where scleractinians were dominant. bicolor, has suggested that ultimately a female Species within the genus Centropyge normally will change sex if and when it is to her advantage occur in complex habitats where polygamous to do so; i.e., if her reproductive fitness is poten- groups predominate. Most Centropyge spp. are tially improved. As pointed out by Moyer (1987) either permanently or temporarily sexually di- such a "choice" is dependent upon proximal chromatic. One might suggest, based on the mechanisms, as follows: a) a female must be able work of Selander (1972), that the scarcity of sexual to avoid aggressive interactions with a dominant dichromatism in the genus Chaetodontoplus may male (Shapiro, 1979; Moyer and Zaiser, 1984) result from a predominance of male-female pairs while b) aggressively dominating a smaller female and/or very small social groups, as was the case (Moyer and Zaiser, 1984). In addition, there is

―462― Moyer: Social and Reproductive Behavior of Pomacanthid probably an as yet unidentified time interval Centropyge Fraser-Brunner (genus Centropyge). within which the sex-changing female must escape In those species for which data are available, i.e. domination by another conspecific, either male or C. tibicen, C. nox, C. flavissimus, and C. vrolicki, female (Moyer, 1987). In male-female pairs and the male rotates his body 180•‹ on the long axis in social groups with only two females and a male, at the moment of spawning, resulting in a simul- i.e. in Bantayan Island situations, such proximal taneous male-female downward dash, with both factors apparently do not normally occur. An fish reaching the substratum at the same time

exception would be, for example, a situation in (Moyer, unpublished data). This differs from which the male in a two-female group was in all other species of pomacanthids for which data frequent conflict with a neighboring male ("ag- are available, representing six of seven pomacan- gressive neglect," Warner and Hoffman, 1980; thid genera, and including Chaetodontoplus, in Moyer, 1984a) and if the two females were which males turn 90•‹ on the long axis when clumped (Moyer and Zaiser, 1984). Such a spawning, leading females to the substratum in scenario was not found to occur at Bantayan the downward dash (or in the case of Genicanthus, Island, and sex change, if it occurs, most likely in the vestigial dip). This suggests the possibility results almost exclusively from the death or dis- that, phylogenetically, the subgenus Centropyge appearance of a male. has diverged from an ancestor of another sub-

Rendezvous sites. Rendezvous sites are known genus Xiphipops Fraser-Brunner type, all of which to be used by at least six pomacanthid species rotate the body 90•‹. (Thresher, 1982; Moyer, 1987). They are also The social organization of a particular species reported in studies of ostraciids (Moyer, 1984b) is not a good indicator of phylogenetic relation- and scorpaenids (Moyer and Zaiser, 1981). In ships as such, due to the important role of the all cases, such sites were used to facilitate location habitat in placing constraints on population size, of mates in situations where population densities sex ratio, and thus, in the composition of social

were low and/or home ranges were quite large over groups. Most pomacanthids for which data are a monotonous topography and when diel spawn- available, however, display almost identical social ing periods were of relatively short duration systems, further indicating the close relationships (Moyer, 1984b) or after dark, when location of within the family. Behaviorally, Chaetodontoplus mates would otherwise be difficult (Moyer and mesoleucus is a member of this large group of

Zaiser, 1981). Future studies will certainly dis- pomacanthid species that includes, among others, close the use of rendezvous sites to be a common all species of Centropyge for which information reef fish tactic under similar conditions. is available, Ho/acanthus tricolor, Pomacanthus Pomacanthid relationships. The close similari- imperator, P. sexstriatus, and Pygoplites diacanthus

ties of Chaetodontoplus mesoleucus in various (Table 2). These species all have the polygamous

aspects of spawning behavior and resource utiliza- potential for single male, multi-female social

tion to other pomacanthid fishes further emphasize groups arranged in size-dominant hierarchies, the confounding phylogenetic complexities within with all species in the group sharing nearly iden- the family (see Moyer, 1987). As shown long tical reproductive behavior. Most display either

ago by Konrad Lorenz, an analysis of the motor permanent or temporary sexual dichromatism, patterns used in courtship can be useful in tracing or both. For the sake of comparison, I propose phylogenetic relationships (Lorenz, 1941). In that this group be considered to represent the nearly all pomacanthid species reported to date, pomacanthid general, unspecialized behavioral including C. mesoleucus, motor patterns associated type. Divergence from the "general" type is with spawning are almost identical. The mid- found in the planktivorous genus Genicanthus, as water habitat of the planktivorous Genicanthus demonstrated by multi-male social groups in G. spp. is reflected in a vestigial post-spawning lamarck, G. semifasciatus, and G. caudovittatus

downward dash that consists merely of a slight dip (Specialized 1 in Table 2; Moyer, 1984c). This of a few cm, followed usually by continued mid- important modification appears to result from a water foraging by females and further courtship mid-water habitat (Moyer, 1984c). Genicanthus by males (Moyer, 1984c). Another interesting melanospilos, however, is found in single-male modification seems to occur in the subgenus social groups with bachelor males, possibly as a

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―465― 魚類学雑誌 Japan. J. Ichthyol. 36(4),1990 result of smaller body size and a corresponding Anim. Behay., 33: 1021-1023. greater dependence upon the substratum for Hioki, S., K. Suzuki and Y. Tanaka. 1982. Spawning shelter (Moyer, 1987). behavior, egg and larval development and sex suc- At least some eastern Pacific Holacanthus cession of the hermaphroditic pomacanthine, Genicanthus melanospilis in the aquarium. J. Fac. (Specialized 2 in Table 2) and both species of Mar. Sci. Tech. Tokai. Univ., 15: 359-366. (In western Atlantic Pomacanthus (Specialized 3 in Japanese.) Table 2) also diverge from the general pattern; Hourigan, T.F. and C.D. Kelley. 1985. Histology e.g., Holacanthus passer forms lek-like groups over of the gonads and observations on the social behavior part of its range in the Sea of Cortez (Moyer et al., of the Caribbean angelfish Holacanthus tricolor. 1983), Pomacanthus arcuatus is promiscuous along Mar. Biol., 88: 311-322. the east coast of Central America (Moyer et al., Lobel, P.S. 1978. Diel, lunar, and seasonal perio- 1983), and P. paru, reported as monogamous by dicity in the reproductive behavior of a pomacanthid Moyer et al. (1983) and others, is polygamous at fish, Centropyge potteri, and some other reef fishes Grand Cayman Island, and probably promiscuous in Hawaii. Pacif. Sci., 32: 193-207. Lorenz, K. 1941. Comparative studies of the motor in dense populations (Moyer et al., in prep.). patterns of Anatinae. Pages 14-114 in K. Lorenz, ed. 1971. Studies in animal and human behavior. Acknowledgments Vol.2. Harvard Univ. Press, Cambridge, Mas- sachusetts. I wish to thank Jonathan Abao, Manuel De- Moyer, J.T. 1981. Interspecific spawning of the sucatan, and Lorna Moyer for assistance in ob- angelfishes Centropyge shepardi and Centropyge servation and logistic support. I am especially bispinosus at Guam. Micronesica, 17: 119-124. grateful to my wife, Lorna Moyer, for urging me Moyer, J.T. 1984a. Comparative reproductive strat- to get back into the ocean and resume my research. egies of labrid fishes from benthic plant and coral This is contribution number 78, Tatsuo Tanaka reef communities. Ph. D. thesis, Univ. of Tokyo, Tokyo, 121pp. Memorial Biological Station. Moyer, J.T. 1984b. Social organization and repro- ductive behavior of ostraciid fishes from Japan and Literature cited the western Atlantic Ocean. J. Ethol., 2: 85-98. Moyer, J.T. 1984c. Reproductive behavior and social Aldenhoven, J. 1984. Social organization and sex organization of the pomacanthid fish Genicanthus change in an angelfish, Centropyge bicolor on the lamarck at Mactan Island, Philippines. Copeia, Great Barrier Reef. Ph. D. thesis, Macquarie Univ., 1984 (1): 194-200. N.S.W.119pp. Moyer, J.T. 1987. Social organization and proto- Aldenhoven, J. 1986. Different reproductive strategies gynous hermaphroditism in marine angelfishes in a sex-changing coral reef fish, Centropyge bicolor (Pomacanthidae). Pages 120-147 in A. Nakazono (Pomacanthidae). Austr. J. Mar. Freshw. Res., and T. Kuwamura, eds. Sex change in fishes. 37: 353-360. Tokai Univ. Press, Tokyo. (In Japanese.) Allen, G.R. 1979. Butterfly and angelfishes of the Moyer, J.T. and A. Nakazono. 1978. Population world. Vol.2. Wiley, New York, 352pp. structure, reproductive behavior, and protogynous Bruce, R.W. 1980. Protogynous hermaphrotism in hermaphroditism in the angelfish Centropyge in- two marine angelfishes. Copeia, 1980(2): 353-355. terruptus at Miyake-jima, Japan. Japan. J. Ich- Burgess, W. and H.R. Axelrod. 1972. Pacific marine thyol., 25 (1): 25-39. fishes. Vol.1. T.F.H. Publ., Neptune City, New Moyer, J.T. and M.J. Zaiser. 1981. Social organiza- Jersey, 280pp. tion and spawning behavior of the pteroine fish Carlson, B.A. 1982. The masked angelfish Geni- Dendrochirus zebra at Miyake-jima, Japan. Japan. canthus personatus. Freshw. Mar. Aquar., 5: 31-32. J. Ichthyol., 28 (1): 52-69. Debelius, H. 1978. Neuv Erkenntnisse ober die Moyer, J.T. and M.J. Zaiser. 1984. Early sex Kaiserfische der Gattung GenicanthusTatsach. Inf. change: a possible mating strategy of Cengropyge Aquar. (TI), 12: 31-34. angelfishes (Pisces: Pomacanthidae). J. Ethol., 2: Ehrlich, P.R. 1975. The population biology of coral 63-67. reef fishes. Ann. Rev. Ecol. System., 6: 211-247. Moyer, J.T., R.E. Thresher and P.L. Colin. 1983. Gronell, A.M. and P.L. Colin. 1985. A toroidal Courtship, spawning and inferred social organiza- vortex for gamete dispersal in a marine fish, tion in American angelfishes. Env. Biol. Fish., 9: Pyglopites diacanthus (Pisces: Pomacanthidae). 25-39.

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Neudecker, S. and P.S. Lobel, 1982. Mating systems (Tatsuo Tanaka Memorial Biological Station, Ako, of chaetodontid and pomacanthid fishes at St. Croix. Miyake-jima, Izu Islands 100-12, Japan) Z. Tierpsychol., 59: 219-318. Randall, J.E. 1975. A revision of the Indo-Pacific angelfish genus Genicanthus, with descriptions of フ ィ リ ピ ン の バ ン タ ヤ ン 島 に お け る チ リ メ ン ヤ ッ コ の 社 three new species. Bull. Mar. Sci., 25: 393-421. 会 行 動 と 繁 殖 行 動 お よ び キ ン チ ャ ク ダ イ 科 の 類 縁 関 係 Selander, R.K. 1972. Sexual selection and dimor- Jack T. Moyer phism in birds. Pages 180-230 in B. Campbell, ed. フ ィ リ ピ ン の バ ン タ ヤ ン 島 に お け る チ リ メ ン ヤ ッ コ Sexual selection and the descent of man. Aldine, Chaetodontoplus mesoleucusの 生 息 場 所 は,変 異 に 乏 Chicago. しい 単 純 な 構 造 の イ シ サ ン ゴ 類 と ウ ミ トサ カ 類 か ら な る Shapiro, D.Y. 1979. Social behavior, group struc- 小 さ な パ ッチ ・ リー フ で あ る.こ こ で は 雄 と 雌 の ペ ア が ture, and control of sex reversal in hermaphroditic 普 通 で,性 比 は わ ず か し か 雌 に 偏 ら な い.し か し,雄1 fish. Pages 43-102 in J.S. Rosenbaltt, R.A. Hinde, 尾,雌2尾 よ りな る グ ル ー プ も見 ら れ,本 種 が 本 来 は 複 C. Beer and M.C. Busnal, eds. Advances in the 婚 で あ る こ と が 分 か る.社 会 グ ル ー プ が 少 数 の 個 体 に よ study of behavior. 10. Academic Press, Berlin. っ て 構 成 さ れ る の は,本 種 の 生 息 場 所 の 構 造 が 単 純 で あ Shen, S.C. and C.H. Liu. 1976. Ecological and る こ と に よ る と考 え ら れ る。 本 種 は 地 形 の 複 雑 な サ ン ゴ morphological study of the fish fauna from waters 礁 で は 見 ら れ な か っ た 。 本 種 の 社 会 行 動 と繁 殖 行 動 は 性 around Taiwan and its adjacent islands 17. A study 転 換 を 行 う そ の 他 の キ ン チ ャ ク ダ イ 科 魚 類 と よ く類 似 し of sex reversal in a pomacanthid fish, Genicanthus て お り,ま た 体 長 に よ る 順 位 関 係 も認 め ら れ る こ と か semifasciatus (Kamohara). Sci. Rep. Natn. Taiwan ら,雌 性 先 熟 で あ る こ と が 示 唆 され る.31種 の キ ン チ Univ., 6: 140-150. ャ ク ダ イ 類 の 行 動 を 比 較 す る と,本 報 告 の チ リ メ ン ヤ ッ Suzuki, K., S. Hioki and K. Iwasa. 1979. Spawning コ を含 め 多 く の 種 が 類 似 し た 行 動 を 示 し,そ れ ら は 一 般 behavior, eggs, larva, and sex reversal of two pom- 型 に 類 別 さ れ る が,タ テ ジ マ ヤ ッ コ 属,東 太 平 洋 の ス ミ acanthid fish, Genicanthus lamarck and G. semi- レ ヤ ッ コ 属,西 大 西 洋 の サ ザ ナ ミ ヤ ッ コ 属 は 行 動 が 特 殊 fasciatus in an aquarium. Publ. Mar. Sci. Mus. で 一 般 型 と 異 な っ て い る.ま た,ア ブ ラ ヤ ッ コ 属 の ア ブ Tokai Univ., 12: 149-165. ラ ヤ ッ コ 亜 属 は 先 祖 型 のXiphipops亜 属 か ら 派 生 し た Thresher, R.E. 1982. Courtship and spawning in the と考 え ら れ る こ と の 根 拠 を示 す と と も に,チ リ メ ン ヤ ッ emperor angelfish Pomacanthus imperator, with コ とキ ン チ ャ ク ダ イ 類 の 性 的 二 型 や ラ ン デ ブ ー ・サ イ ト comments on reproduction in other pomacanthid に つ い て も 論 議 し た. fishes. Mar. Biol., 70: 149-156. Warner, R.R. and A.G. Hoffman. 1980. Population (100-12東 京 都 三 宅 村 阿 古 田 中 達 男 記 念 生 物 実 験 所) density and the economics of territorial defense in a coral reef fish. Ecology, 61: 772-780.

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