Deretrema philippinensis n. sp. (Digenea: Zoogonidae)

Deretrema philippinensis n. sp. (Digenea: Zoogonidae) from Anomalops katoptron (Beryciformes: Anomalopidae) from the Philippines M. BEVERLEY-BURTON Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ont., Canada NlG 2Wl

Can. J. Zool. Downloaded from www.nrcresearchpress.com by 199.201.121.12 on 05/28/13 For personal use only.

AND

G . EARLY New England Aquarium, Central Wharj; Boston, MA, U.S.A. 02 110 Received February 18, 1982

BEVERLEY-BURTON, M., and G. EARLY.1982. Deretrema philippinensis n. sp. (Digenea: Zoogonidae) from Anomalops katoptron (Beryciformes: Anomalopidae) from the Philippines. Can. J. Zool. 60: 2403-2408. Deretremaphilippinensis n. sp. is proposed for zoogonid Digenea found in pairs in the gallbladder of 10 of 12 flashlight fish (Anomalops katoptron Bleeker) from the Philippines. Deretrema philippinensis is characterized by intestinal caeca extending posterior to the testes to the posterior one-fourth of body length; comparatively large oral and ventral suckers; ratio of oral sucker : ventral sucker, 1:1.18- 1.36; ventral sucker equatorial; comparatively small testes situated at level of ventral sucker and extensive uterine coils in the preacetabular region. These features are used to separate D. philippinensis from the 17 described species currently assigned to Deretrema. The importance of some of the morphological features previously used in the separation of Deretrema spp. is briefly discussed. BEVERLEY-BURTON, M., et G. EARLY.1982. Deretrema philippinensis n. sp. (Digenea: Zoogonidae) from Anomalops katoptron (Beryciformes: Anomalopidae) from the Philippines. Can. J. Zool. 60: 2403-2408. Le nom de Deretrernaphilippinensisn. sp. est proposk ici pour dksigner les digkniens zoogonidks rencontrks par paires dans la vksicule biliaire de 10 des 12 Anomalops katoptron Bleeker examinks, capturks aux Philippines. Chez D. philippinensis, les caecums intestinaux se prolongent derriere les testicules jusqu'a la limite du quart postkrieur de la longueur totale, les ventouses orale et ventrale sont relativement grandes, le rapport ventouse ora1e:ventouse ventrale est de 1:1,18- 1,36, la ventouse ventrale est kquatoriale, les testicules sont relativement petits et se situent au niveau de la ventouse ventrale, enfin l'utkrus comporte d'importantes boucles dans la rkgion prkacktabulaire. Ces structures sement a skparer D. philippinensis des 17 especes connues du genre Deretrema. L'importance de certains traits utilisks jusqu'a ce jour pour distinguer les especes de Deretrema fait l'objet d'une discussion. [Traduit par le journal]

Introduction

a coverslip supported at the corners by petroleum jelly to provide controlled, slight pressure. The saline was removed with bibulous paper and replaced with cold acetic acid formalin - alcohol (AFA) for fixation. Worms were stored in AFA, stained routinely in acetocarmine, dehydrated in a graded series of ethanol, cleared in methyl benzoate, and mounted in Permount. Measurements were taken from drawings made with a camera lucida. Measurements (unless otherwise stated) are recorded in millimetres (mrn) and are expressed as those of the holotype followed (in parentheses) by the mean and range.

Flashlight fish (Anomalops katoptron Bleeker, 1878) are small (6 cm), fast-moving beryciform teleosts which occur in the South Pacific. Because of their spectacular nocturnal photophore display, they make an attractive marine exhibit and have been shipped to various aquaria. B u m (1980) reported finding a diverse group of helminths, i ~ c l u d i n gan unnamed Deretrema sp., in flashlight fish which died at the New York Aquarium. In routine postmortem examinations of fish at the New ~ n ~ l a n d ~ ~ u a r Boston, i u m , zoogonids were also found Results in A. katoptron and are herein described as Deretrema Zoogonidae Odhner, philippinensis n . sp. Steganodermatinae Yamaguti, 1934 Deretrema Linton, 19 10 Materials and methods Deretrema philippinensis n. sp. Figs. 1-4, Table 1 Flashlight fish were caught by hand, at night, in water HOST: Anomalops katoptron Bleeker, 1878, flash6-25 m deep off Buyong Beach, Mactan Island, Cebu, Philippines, and were shipped to the New England Aquarium, light fish (Beryciformes). PREVALENCE A N D INTENSITY: 1 0 of 12 fish examined Boston, MA, U.S.A. Fish which died were examined immediately for helminths. Worms from the gallbladder were washed (82%) with two worms per infected fish. in saline (0.9% NaCl), placed on a glass slide, and covered by LOCATION IN HOST: Gallbladder. 0008-4301 /82/ 102403-06$01.OO/O 01982 National Research Council of Canada/Conseil national de recherches du Canada


CAN. J. ZOOL. VOL. 60, 1982

FIG.1. Deretremaphilippinensis n. sp. (Composite drawing based on the deposited type material.) Entire worm, ventral view. Tegumental spines not depicted. GEOGRAPHIC LOCALITY: Buyong Beach, Mactan Island, Cebu, Philippines (caught in water 6-25 m deep). MATERIAL STUDIED: Eight worms were available: the specific description is based on three intact specimens deposited in the Invertebrate Collection (Parasites),

National Museum of Natural Science, Ottawa, Ontario, Canada KIA OM8, Nos. NMCIC(P) 1982 0075-0077; additional; morphological information was taken from the other five worms. DESCRIPTION: With characters of the genus Deretrema as stated by Yamaguti (1971). Body oval in outline con-


BEVERLEY-BURTON AND EARLY

FIGS.2-4. Deretrema philippinensis n. sp. (Composite drawings based on the deposited type material.) Fig. 2. Oral sucker and anterior gut components to show position of denticles. Fig. 3. Cirrus sac to show bipartite seminal vesicle, pars prostatica and ejaculatory duct. Metratenn not depicted. Fig. 4. Ovarian complex to show oviduct, seminal receptacle, vitelline ducts, Laurer's canal and ootype surrounded by Mehlis' gland cells.

cave ventrally 4.46 (4.27:3.88-4.48) long by 2.62 (2.66:2.55-2.82) in maximum (midbody) width; tegument spinose, spines smaller posteriorly. Oral sucker 0.61 (0.60:0.59-0.61) long by 0.70 (0.75:0.70-0.79) wide; prepharynx short; pharynx 0.39 (0.38:O.33-0.4 1) Iong by 0.36 (0.33:O.30-0.36) wide, pharyngeal spines present in anterior region; oesophagus up to 0.13 long; small spines present in posterior region of caecal bifurcation; caeca wide, extending into posterior onefourth of total body length. Ventral sucker equatorial, 0.89 (0.96:0.89-1.07) long by 0.92 (0.97:0.92-1.05) wide. Ratio transverse diameters oral sucker:ventral 1:1.31 (1:1.29 (1:1.18-1.36)). Testes oval, at level of ventral sucker, ventral or lateral to caeca; right testis 0.25 (0.19:O. 15-0.25) long (anteroposterior diameter) by 0.16 (0.22:O. 16-0.26) wide; left testis 0.23 (0.17: 0.13-0.23) long by 0.16 (0.22:O. 16-0.26) wide. Cirrus sac claviform, 0.33 long by 0.1 1 (measured on one deposited paratype) usually obscured by uterus; internal

seminal vesicle bipartite; proximal vesicle smaller and thin-walled, distal vesicle larger and thick-walled; pars prostatica surrounded by prostatic cells; ejaculatory duct opens through unarmed cirrus; genital pore ventral, at oesophageal level, submarginal, usually on left (seven of eight specimens) rarely on right. Ovary rounded, median or submedian, dorsal or (rarely) posterior to posterior region of ventral sucker, 0.34 (0.37:0.340.39, two specimens) long by 0.33 (0.36:0.33-0.38, two specimens) wide; seminal receptacle 0.13 (0.11: 0.08-0.13, two specimens) long by 0.13 (0.13:O. 120.13, two specimens) wide, posterior or posterolateral to ovary; Laurer's canal opens dorsal to posterior margin of ovary; Mehlis' gland distinct if not obscured by uterine coils. Vitelline follicles, up to 0.28 in maximum diameter, in clusters of 11 (10:8-11) on left and 8 (9:8-10) on right, pretesticular and partially extracaecal. Uterus with voluminous coils extending well into posterior one-fifth of body and extracaecal area in

2406



posttesticular region; ascending uterus passing dorsal to lateral to the acetabulum (D. plotosi and D. haplogventral sucker; preacetabular coils massive, extending nathi), while D. philippinensis has testes which lie at the laterally to area of vitelline follicles; metraterm thin- level of the ventral sucker. Deretrema philippinensis is larger in body size than walled and, when empty, slender, running alongside cirrus sac and opening beside cirrus at genital pore. Eggs any of the last named eight species and has considerably 45 pm (mean) (43-47 pm) long by 22 pm (mean) larger oral and ventral suckers (Table 1). In addition, the (19-25 pm) wide. Excretory pore terminal, excretory ratio of the oral sucker to ventral sucker in all except D. haplognathi differs from that of D. philippinensis. vesicle tubular, obscured by uterine coils anteriorly. The precise extent of the caeca is not known for the Discussion type species, D. fusillus Linton, 1910, or D. paraIn late 1978, 40 specimens of A . katoptron were priacanthi Yamaguti, 1959. Deretrema fusillus was introduced at the New England Aquarium, Boston, MA, described from a single specimen followed by descripU .S.A. Although 17 died over the following 3 years, the tions of another two specimens which Linton (1910) remainder survive at the time of writing. Burn (1980) referred to as D. fusillus with "much hesitation." Linton noted the difficulty of keeping flashlight fish and (1940) identified further specimens as D. fusillus, reported a 100% prevalence of Deretrema sp., with an again providing a description and figures. From a study intensity of two worms per host, in the 16 fish of Linton's papers, it would appear that the material necropsied. Burn (1980) discussed the apparent regula- represents more than one species and, consequently, we tion of the digenean population and our findings con- have compared D. philippinensis only with the holotype cerning intensity support Burn's observations. The description. Deretrema fusillus resembles D. philippigallbladders of infected fish examined in the present nensis in having well developed preacetabular uterine study were noticeably distended by the parasites which coils, but differs in the position of the testes and did not, however, produce obvious gross pathological vitellaria. In addition, D. fusillus is comparatively small (1.82 by 0.64) with small oral and ventral suckers changes in the wall of the gallbladder or liver. Yamaguti (1971) included 17 species in the genus (0.25 and 0.43 in diameter, respectively). Deretrema Deretrema . Subsequently Overstreet and Pritchard parapriacanthi also has extensive preacetabular uterine ( 1977) transferred D . pycnorganum (Rees, 1953) coils but, from Yamaguti's (1959) description, it differs Yamaguti, 1958, to Brachyenteron Manter, 1934, and from D. philippinensis in having testes lying well Madhavi ( 1979) proposed D . dermacetabulum. From a behind the ventral sucker which is clearly preequatorial. study of the original descriptions, we find, in having Further, the oral and ventral suckers of D. paraintestinal caeca extending posteriad to the testes, D. priacanthi are proportionally small with a ratio of philippinensis is unlike the following seven species in 1:1.5-1.6. Typically, species of the genus Deretrema are found which the caeca end either anterior to or at the level of the testes: D. fellis (Yamaguti, 1934) Yamaguti, 1940; in the gallbladders of a wide variety of marine teleosts D. sebastodis (Yamaguti, 1934) Yamaguti, 1940; D. from the Pacific. Most known hosts belong to the cholaeum McFarlane, 1936; D . nahaense Yamaguti, Perciformes although members of the Atheriniformes, 1942 (also described by Kamegai 1973); D. pacijicum Scorpaeniformes , Beryciformes and Siluriformes have Yamaguti, 1942; D. pooli Annereaux, 1947 and D. also been recorded. Deretrema minutum is the only minutum Manter, 1954. Further, in the above species species of the genus known from a catadromous host as (except D. minutum) the testes lie in the posterior half of it occurs in the intestine of a galaxid (Salmoniformes) the body, while in D. philippinensis, the testes lie in the taken in New Zealand (Manter 1954). However, the posterior half of the body and are at the level of the generic designation of D. minutum is questionable as overstreet and Pritchard (1977) considered it to be an ventral sucker. Another eight Deretrema spp. (Table 1) resemble D. "atypical Deretrema . . . most similar" to their newly philippinensis in having caeca which extend posterior to proposed Panopula cavernossa . Only two Deretrema the testes: D. hoplognathi Yamaguti, 1940; D. plotosi spp. have been reported from hosts taken outside the Yamaguti, 1940; D. acutum Pritchard, 1963; D. caran- Pacific: D. dermacetabulum from the Bay of Bengal gis Yamaguti, 1970; D. hawaiiense Yamaguti, 1970; (Madhavi 1979) and an unnamed Deretrema sp. (conD. sphyranae Yamaguti, 1970; D. uku Yamaguti, 1970 sidered close to D. plotosi) from the Mediterranean nd D. dermacetabulum. However, all the above (Paggi and Orrechi 1976). As a generalization, the genus has probably evolved species are lacking the heavy preacetabular uterine coils characteristic of D. philippinensis; all the above in Pacific Perciformes and later acquired nonperciform species have testes which are either completely post- hosts. Yamaguti ( 1942) described D . pacijicum from a acetabular (D . acutum, D . carangis, D . hawaiiense, beryciform (Monocentris japonica) taken off the coast D . sphyranae, D. uku, D . dermacetabulum) or postero- of Japan thus the finding of D. philippinensis in A .

2407

BEVERLEY-BURTON AND EARLY

TABLE1. Comparative measurements (in millimetres except where otherwise stated) of Deretrema spp. characterized by gut caeca extending posterior to testicular level

Author Yamaguti 1940 Y amaguti 1940

D . acutm

Pritchard 1963 Y amaguti 1940

D . carangis D . hawaiiense

Yamaguti 1970 Yamaguti 1970

D . sphyrenae

Yamaguti 1970

D . uku

Y amaguti 1970

D . dermacetabulum D . philippinensis n. sp.

Madhavi 1979 Present study


D . hoplognathi D . plotosi

Body length

Oral sucker width

Ventral Ratio of sucker width OS:VS* width

1: 1.82 1: 1.969

Eggs (km)

40-42 X 26-27 37-42 x 23-28

1: 1.7-2.8 32-49 "Approximately 32-49 1:2" Approximately 35-44 1:29 1:2.3-2.5 37-46

X

20-26 2 1-28

X

2 1-28

X

18-28

X

*OS, oral sucker, VS, ventral sucker. tWorms "fixed in alcohol." $Worms "subjected to coverglass pressure when fixed." $Calculated by present authors.

katoptron is the second beryciform to be named as a host for this genus.

Morphological features used in taxonomic dlfferentiation Yamaguti (197 l), in his key to the genera of Steganodermatinae, used the feature "caeca reaching a little further posteroir to testes" in identifying Deretrema and, in the generic diagnosis, stated "caeca terminating a little posterior to testes." In order to accommodate D. philippinensis, it is suggested the above clause should read "caeca terminating posterior to testes." In D. minutum, as described by Manter (1954), the caeca end in front of the testes but, as noted above, this species is, in some respects, different from other Deretrema spp. Therefore, rather than emend the generic diagnosis we believe that D . minutum, after further study should be removed from Deretrema . Yamaguti (1970) relied heavily on the characteristics of Laurer's canal to differentiate between D. carangis, D. hawaiiense, D. sphyranae, and D. uku from Hawaiian fishes. We suggest caution if the positon of the opening of Laurer's canal and the presence or absence of convolutions are used as taxonomic characters as they tend to vary with the state of contraction or expansion of the body of the worm and, according to Yamaguti (1970), coverslip pressure during fixation. In any event, it is often difficult to see Laurer's canal in whole mounts as it may be obscured by uterine coils. Similarly, we do not consider the size of the seminal receptacle as used by Yamaguti (1970) to be a good taxonomic character as it appears to depend on the reproductive state of indivi-

dual worms: in worms which have distinct, functional gonads, the receptacle is conspicuous, while in senescent worms, in which the gonads are indistinct, the receptacle is no longer visible and the whole body becomes packed with distended uterine coils. Eleven of the species now included in the genus Deretrema were proposed by Yamaguti (1934, 1940, 1942, 1959, 1970): D .fellis and D . sebastodis (based on one and two specimens respectively) were considered by Yamaguti (1934) to be "closely related" as were D. plotosi and D. hoplognathi (Yamaguti 1940). D. pacijicum and D. nahaense (based on single specimens) were stated to resemble each other closely (Yamaguti 1942). Further examination of type material and a revision of the genus might well result in the synonymy of several of these and other species as we consider some of the features listed are not taxonomically useful in s~eciesse~aration. I

I

Acknowledgements We thank Mr. G. Klassen for technical assistance. a grant to M.B.-B. Financial support was provided from the Natural Sciences and Engineering Research (grant No. 80 ANNEREAUX, R. F. 1947. Three new trematodes from marine fishes of California. Trans. Am. Microsc. Soc. 66: 249255. dependent regulation of a fish BURN, R. 1980. bematode population. J . parasitol. 66: 173- 174. KAMECAI, S. 1973. Zoogonid trematodes from marine fishes near the Tsushima Islands in the Sea of Japan. Res. Bull. Meguro Parasitol. Mus. 7: 19-23.

2408



LINTON,E. 1910. Helminth fauna of the Dry Tortugas. 11. Trematodes. Carnegie Inst. Washington Publ. 133: 15-98. 1940. Trematodes from fishes mainly from the Woods Hole region, Massachusetts. Proc. U.S. Natl. Mus. 88: 1-172. MADHAVI, R. 1979. Digenetic trematodes from marine fishes of Waltair coast, Bay of Bengal. Family Zoogonidae. Riv. Parassitol. 40: 249-259. MANTER, H. W. 1954. Some digenetic trematodes from fishes of New Zealand. Trans. R. Soc. N.Z. 82: 475-568. MCFARLANE, S. H. 1936. A study of the endoparasitic trematodes from marine fishes of Departure Bay, B.C. J. Biol. Board Can. 2: 335-347. OVERSTREET, R. M., and M. H. PRITCHARD. 1977. Two new zoogonid digenea from deep-sea fishes in the Gulf of Panama. J. Parasitol. 63: 840-844. PAGGI,L., and P. ORECCHIA. 1976. Su di una nuova specie Plagioporus (Caudotestis) tyrrhenicus sp. n. e su due nuovi reperti parassitologici in Blennius pavo Risso, 1810. Parassitologia (Rome), 18: 2 1-32.

PRITCHARD, M. H. 1963. Studies on digenetic trematodes of Hawaiian fishes, primarily families Lepocreadiidae and Zoogonidae. J. Parasitol . 49: 578-587. REES,G. 1953. Some parasitic worms from fishes off the coast of Iceland. 11. Trematoda (Digenea). Parasitology, 43: 15-26. YAMAGUTI, S. 1934. Studies on the helminth fauna of Japan. 2. Trematodes of fishes, I. Jpn. J. Zool. 5: 249-541. 1940. Studies on the helminth fauna of Japan. 31. Trematodes of fishes, VII. Jpn. J. Zool. 9: 35- 108. 1942. Studies on the helminth fauna of Japan. 39. Trematodes of fishes mainly from Naha. Transactions of the Biogeographical Society of Japan, 3: 329-398. 1959. Studies on the helminth fauna of Japan. 54. Trematodes of fishes, XIII. Publ. Seto Mar. Biol. Lab. 7: 24 1-262. 1970. Digenetic trematodes of Hawaiian fishes. Keigaku Publishing Co., Tokyo. 1971. Synopsis of digenetic trematodes of vertebrates. Vol. 1 and Vol. 2. Keigaku Publishing Co., Tokyo.