MEM INST OSWALDO CRUZ, RIO DE JANEIRO, 94(5) Sep/Oct 1999
PAGES: 615-618 DOI: Full paper
Redescription of Rhamnocercus stichospinus Seamster and Monaco, 1956 (Monogenea: Diplectanidae), Parasitic on Menticirrhus americanus (Osteichthyes: Sciaenidae) from the Coastal Zone of the State of Rio de Janeiro, Brazil

Nilton N Chaves, José Luis Luque+ ++, Anderson D Cezar ++

Curso de Pós-Graduação em Medicina Veterinária-Parasitologia Veterinária, Departamento de Parasitologia Animal, Universidade Federal Rural do Rio de Janeiro, Caixa Postal 74508, 23851-970 Seropédica, RJ, Brasil

Abstract

Rhamnocercus stichospinus Seamster and Monaco, 1956 (Diplectanidae) parasitic on the sciaenid fish Menticirrhus americanus from the coastal zone of the State of Rio de Janeiro, is redescribed and recorded for the first time in the South American Atlantic Ocean. The generic diagnosis of Rhamnocercus is emended to accommodate the presence of confluent intestinal ceca in R. stichospinus.

Studies on polyonchoinean monogeneans, parasitic on marine teleost fishes, from Brazilian coastal zone are scarce. To date, three species were recorded: Encotyllabe spari Yamaguti, 1934 parasitic on Haemulon sciurusOrthopristis ruberand Micropogonias furnieri; Rhamnocercus rham-nocercus Monaco, Wood and Mizelle, 1954 parasitic on Micropogonias furnieri, and Mexicana atlantica Luque, Amato and Takemoto, 1993 parasitic on Haemulon steindachneri (Kohn et al. 1984, 1989, Luque et al. 1993, 1996).

During a parasitological survey of marine fishes from the coastal zone of the State of Rio de Janeiro, Brazil, 115 specimens of the sciaenid fish Menticirrhus americanus Linnaeus were necropsied and numerous polyonchoinean specimens were collected. In the present paper, Rhamnocercus stichospinus Seamster and Monaco, 1956 is redescribed and illustrated. This species is recorded for the first time from the coastal zone of the South America Atlantic Ocean. The generic diagnosis of Rhamnocercus Monaco, Wood and Mizelle, 1954 is emended herein.

 

MATERIALS AND METHODS

The monogeneans studied are part of the material collected from 115 specimens of M. ame-ricanus, from the coastal zone of the State of Rio de Janeiro, Brazil (22º30'S, 41º23'W - 22º43'S, 41º40'W) during 1996. Specimens of M. americanus were identified according to Menezes and Figueiredo (1980). The fishes measured 28.4 ± 7.7 (17-48) cm of total length, and weighed 335.7 ± 329.5 (54-1580) g. The monogeneans were fixed and preserved in 5% formalin. The parasites were stained with Gomori's trichrome and mounted in Canada balsam. Measurements were made in micrometers (µm); the range is followed by the mean within parentheses. The illustrations were made with the aid of a drawing tube mounted on a Wild M-20 phase contrast microscope. The terms prevalence and mean intensity were used according to Bush et al. (1997). Voucher specimens were deposited in the Coleção Helmintológica do Instituto Oswaldo Cruz (CHIOC), Rio de Janeiro, Brazil and in the United States National Parasite Collection (USNPC), Maryland, USA.

 

RESULTS

Monogenea van Beneden, 1858

Polyonchoinea Bychowsky, 1937

Dactylogyrinea Bychowsky, 1937

Diplectanidae Monticelli, 1903

Rhamnocercus Monaco, Wood and Mizelle, 1954 emended

Emended diagnosis: Diplectanidae. Peduncle long, slender, covered with two longitudinal rows of dorsal and ventral hook-like spines. Intestinal ceca confluent posteriorly. Testis post-germarian, copulatory organ straight or coiled, without accessory piece. Germarium pretesticular, oviduct looping around right intestinal cecum. Vaginal aperture sinistrodorsal. Parasitic on marine sciaenid fishes.

Type speciesRhamnocercus rhamnocercus Monaco, Wood and Mizelle, 1954

Other species: r. bairdiella Hargis, 1955; R. stichospinus Seamster and Monaco, 1956; R. oliveri Luque and Iannacone, 1991, and r. stelliferi Luque and Iannacone, 1991.

Rhamnocercus stichospinus Seamster and Monaco, 1956

(Figs 12-9)

Redescription (based on 20 whole-mount, 10 measured): body 880-1200 (990), elongate (Fig. 1); greatest width 133-186 (157) in anterior trunk. Cephalic lobes well developed, four pairs of cephalic glands. Tegument smooth. Four eyes. Peduncle 264-352 (314) long, 97-132 (114) wide, slender, elongate, with two longitudinal rows of hook-like spines of 18-23 each (Fig. 1); ventral spines (Fig. 2) 24-42 (34) long, with round base; dorsal spines (Fig. 3) 32-64 (50) long, increasing its size toward haptor. Haptor 352-476 (388) long, 238-282 (254) wide, laterally expanded, with spine groups distributed irregularly. Two similar dorsal bars (Fig. 4) 100-119 (107) long, 9-12 (10) wide, round extremities; ventral bar (Fig. 5) 150-170 (160) long, 12-16 (14) wide, elongate, acute extremities, longitudinal groove, middle notch. Anchors dissimilar; ventral anchor (Fig. 6) 59-66 (63) long, elongate deep root; poorly developed superficial root; straight shaft and short point; dorsal anchor (Fig. 7) 60-70 (64) long, elongate deep root, developed superficial root; evenly curved shaft and short point. Fourteen hooks (Fig. 8) 11-13 (12) long; similar, delicate point and shaft; erect thumb; long, curved shank; FH-loop 4/5 shank length; six pairs lying on lateral haptorial margins, one pair located posterior to ventral bar. Mouth subterminal; pharynx 32-44 (38) long, 30-46 (38) wide, sub-espherical; intestinal ceca confluent posteriorly. Testis 40-50 (44) long, 32-44 (40) wide, post-germarian; oval prostatic reservoir, sinistral to copulatory organ. Copulatory organ (Fig. 9) 120-144 (126) long, 30-50 (36) wide; distal portion tubular, with twisted appearance in its proximal half; accessory piece absent. Germarium 34-50 (42) long, 40-56 (46) wide; oviduct looping around right intestinal cecum. Mehlis's gland conspicuous; uterus short and tubular, eggs not observed. Vaginal aperture sinistrodorsal, not sclerotised. Vitellaria limited to trunk.

Site of infestation: gills.

Specimens examined: two paratypes of Rhamnocercus stichospinus Seamster and Monaco, 1956 parasitic onMicropogonias undulatus (Linnaeus), from Texas, USA (USNPC No. 37498). Paratype of Rhamnocercus rhamnocercusMonaco, Wood and Mizelle, 1954 parasitic on Umbrina roncador Jordan and Gilbert from California, USA (USNPC No. 49426). Paratype of Rhamnocercus bairdiella Hargis, 1955 parasitic on Bairdiella chrysura (Lacépède) from Florida, USA (USNPC No. 49346).

Prevalence: 30.4%.

Mean intensity: 18.8.

Voucher specimens: CHIOC No. 33959 a-f (six stained whole mount), USNPC No. 88246 (two stained whole mount).

Remarks: Seamster and Monaco (1956) described this species from Menticirrhus littoralis and Micropogonias undulatus(type host) from Texas, USA. Zwerner and Lawler (1972) recorded R. stichospinus from M. americanus from Cheasapeake Bay, USA. Original description and illustrations provide scarce information on the internal morphology ofR. stichospinus.

Rhamnocercus was established by Monaco et al. (1954) and is characterized by species having hook-like spines longitudinally distributed on the peduncle and by accessory spines clumped on the haptor. Hargis (1955) emended the diagnosis of the genus and added some information on the internal morphology and the peduncle spines. In relation to the intestinal ceca, Hargis (1955) stated "...crura unramified, apparently confluent posteriorly...". Both, Hargis (1955) and Seamster and Monaco (1956) discussed the validity of Rhamnocercinae Monaco, Wood and Mizelle, 1954, as a subfamily of Diplectanidae Monticelli, 1903 due to the possible homology of the peduncle spines with the squamodiscs.

Luque and Iannacone (1991) observed, for the first time, confluent ceca in Rhamnocercinae and, following Oliver (1987), placed the species described by them into Rhamnocercidae. The taxonomic act of Luque and Iannacone (1991) is not valid because these authors followed the criteria of Oliver (1987), which in his unpublished doctoral dissertation, mentioned Rhamnocercinae at the family status. According to the International Code of Zoology Nomenclature (Article 9), dissertation does not constitute valid publication.

The type material of the Atlantic species of Rhamnocercus deposited in the USNPCdoes not allow observation of internal morphology but the observation of Luque and Iannacone (1991), in relation to ceca, is confirmed by the examination of Brazilian specimens of R. stichospinus. Yamaguti (1963) and Hargis (1955) mentioned that Diplectanidae Monticelli, 1903 is composed by species with intestinal ceca not confluent. Monaco et al. (1954), Hargis (1955), Seamster and Monaco (1956), and Yamaguti (1963) include Rhamnocer-cus as a genus or subfamily (Rhamnocercinae) of Diplectanidae. Confirmation of the confluence of the intestinal ceca in the Peruvian and Brazilian specimens, suggest that a possible change on the taxonomic status of Rhamnocercinae should be tested through a phylogenetic analysis of Diplectanidae.

 

ACKNOWLEDGMENTS

To Dr Ralph Lichtenfels, Curator of the United States National Parasite Collection, Maryland, USA, for loaning paratypes of some Rhamnocercus species.

 

REFERENCES

Bush AO, Lafferty KD, Lotz JM, Shostak AW 1997. Parasitology meets ecology on its own terms: Margolis et al. revisited. J Parasitol 83: 575-583.

Hargis Jr WJ 1955. Monogenetic Trematodes of Gulf of Mexico Fishes. Part III. The Superfamily Gyrodactyloidea (Continued). Quart J Florida Acad Sci 18: 33-47.

Kohn A, Abramson B, Macedo B 1984. Studies on some monogenean parasites of Haemulon sciurus (Shaw, 1803) (Pomadasyidae). J Helminthol 58: 213-218.

Kohn A, Santos CP, Cohen SC 1989. Monogenean parasites of Micropogonias furnieri (Desmarest, 1823) (Pisces, Sciaenidae) from the littoral of Rio de Janeiro State, Brazil. Mem Inst Oswaldo Cruz 84 (Suppl. IV): 291-295.

Luque JL, Iannacone J 1991. Rhamnocercidae (Mono-genea: Dactylogyroidea) in Sciaenid fishes from Peru, with description of Rhamnocercoides menticirrhi n. gen, n. sp. and two new species of RhamnocercusRev Biol Trop 39: 193-201.

Luque JL, Amato JFR, Takemoto R 1993. A new species of Mexicana (Monogenea: Dactylogyridae) parasitic onHaemulon steindachneri (Jordan & Gilbert) (Osteichthyes: Haemulidae) from the Brazilian coast. Rev Brasil Parasitol Vet 1: 85-88.

Luque JL, Amato JFR, Takemoto RM 1996. Comparative analysis of the communities of metazoan parasites ofOrthopristis ruber and Haemulon steindachneri (Osteichthyes: Haemulidae) from the southeastern Brazilian littoral: I. structure and influence of the size and sex of hosts. Rev Brasil Biol 56: 279-292.

Menezes NA, Figueiredo JL 1980. Manual de Peixes Marinhos do Sudeste do Brasil. IV. Teleostei (3). Museu de Zoologia, Universidade de São Paulo, São Paulo, 96 pp.

Monaco LH, Wood RA, Mizelle JD 1954. Studies on Monogenetic Trematodes. XVI. Rhamnocercinae, a new subfamily of Dactylogyridae. Am Midl Nat 52: 129-132.

Oliver G 1987. Les Diplectanidae Bychowsky, 1957 (Monogenea, Monopisthocotylea, Dactylogyridea). Systématique. Biologie. Ontogénie. Ecologie. Essai de phylogenèse, PhD Thesis, Université des Sciences et Techniques du Languedoc, 340 pp.

Seamster A, Monaco LH 1956. A new species of Rhamnocercinae. Am Midl Nat 55: 180-183.

Yamaguti S 1963. Systema Helminthum. Vol. IV. Monogenea & Aspidocotylea, Inc. Publishers, New York, 699 pp.

Zwerner D, Lawler AR 1972. Some parasites of Chesapeake Bay fauna, p. 78-94. In ML Wass, A Checklist of the Biota of Chesapeake Bay, Virginia Institute of Marine Sciences Report No. 65, Virginia, USA.  

+Corresponding author. Fax: +55-21-682.1617. E-mail:  This e-mail address is being protected from spambots. You need JavaScript enabled to view it.  .
++CNPq research fellows.
Received 11 May 1998
Accepted 27 April 1999

This work was partially supported by Faperj.

CONTACT US

Memórias do Instituto Oswaldo Cruz

Av. Brasil 4365, Castelo Mourisco
sala 201, Manguinhos, 21040-900
Rio de Janeiro, RJ, Brazil

Tel.: +55-21-2562-1222

This e-mail address is being protected from spambots. You need JavaScript enabled to view it.

twitterfacebook

SUPPORT PROGRAM

marca fiocruzmarca brasil
marca faperjmarca cnpqmarca capes n marca cope

and diabetes. Erection dysfunction or ED is certainly one of mens most usual problem. It changes buy tadalafil 60mg A common drug is actually an imitation of its manufacturer twin. Both ought to be same in female cialis 20mg Long Phrase Viagra Use Fundamentally Damages Sex Lives This discount cialis canada Equally so, theres something to be said for the wonder of the second, captured forever on picture or a buy cheap cialis People extremely annoyed that they could only get three weeks at a time, Bunker noted. Retired persons cheap pharmacy These types of matters are possibly to being identified as having a result of cancer buy cialis 40mg - Yoghourt - fat-free simply Physical causes: Buying generic medicines now has been cheap generic cialis Herbaceous plants like nigrum and tribulus are well-known for his or her qualities in defeating impotence, which tadalafil 10mg It is not hard to consider Cialis that is generic. Most men start with one-10 mg dosage each purchase cialis Tadalafil quickly gained the moniker of weekender in Paris due to the fabulous results. The bash freaks buy female cialis