Proc. Helminthol. Soc. Wash. 56(2), 1989, pp. 125-127 Scleroductus yuncensi gen. et sp. n. (Monogenea) from Pimelodella yuncensis (Siluriformes: Pimelodidae) in Peru CESAR A. JARA' AND DAVID K. CoNE2 1 Department of Microbiology and Parasitology, Faculty of Biological Sciences, Trujillo, Peru and 2 Department of Biology, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3 ABSTRACT: Scleroductus yuncensi gen. et sp. n. (Gyrodactylidea: Gyrodactylinae) is described from Pimelodella yuncensis Steindachner, 1912 (Siluriformes; Pimelodidae), from fresh water in Peru. The new material is unique in having a bulbous penis with 2 sclerotized ribs within the ejaculatory duct and a sclerotized partial ring surrounding the opening. The hamuli are slender and with thin, continuously curved blades. The superficial bar has 2 posteriorly directed filamentous processes in place of the typically broad gyrodactylid ventral bar membrane. Scleroductus is the fourth genus of the Gyrodactylidea to be described from South America, all of which occur on siluriform fishes. KEY WORDS: Scleroductus yuncensi gen. et sp. n., Gyrodactylidea, Monogenea, Peru, Pimelodella yuncensis. During a parasite survey of freshwater fishes Scleroductus yuncensi sp. n. of Peru, one of us (C.A.J.) found a previously (Figs. 1-5) undescribed viviparous monogenean from the DESCRIPTION (12 specimens studied; 6 speci- external surface of Pimelodella yuncensis that mens measured): Partially flattened holotype could not be classified into any known genus 460 (400-470) long, 90 wide at midlength. Bul- within the Gyrodactylidea (Baer and Euzet, 1961). bous pharynx 42 (35-45) wide. Penis bulbous, The present study describes the new material as 15 (15-16) in diameter; armed with 2 sclerotized Scleroductus yuncensi gen. et sp. n. ribs 16 (15-16) long within wall of ejaculatory duct, sclerotized, horseshoe-shaped spinous ring Materials and Methods on the surface of the bulb at the duct opening. Forty-eight host specimens measuring approximate- Gland cells of penis not seen. Hamuli relatively ly 10cm long were collected by netting tributaries of slender, 75 (76-78) long; root 33 (32-35), shaft the Chicama River, Ascope Province, Peru. Parasites 60 (59-62), point 32 (30-35). Hamulus point were collected by the dislodgement method of Mizelle curved on both inner and outer surfaces. Super- and Kritsky (1967) and fixed in 5% formalin. The spec- imens were mounted unstained in glycerine jelly. Mea- ficial bar dumbbell-shaped, 16 (12-18) wide, 4 surements of the holotype are followed in parentheses (4-5) long; anterolateral processes absent; bar by those of the paratypes. All measurements are in membrane in form of 2 longitudinal filamentous micrometers. Descriptive terminology follows Malm- processes, 23 (20-30) long. Deep bar simple, berg (1970). without median notch, 13 (13-18) wide. Mar- ginal hooks 20 (20-21) long. Sickle small, 5 (4- Results 5) long, 5 (5-6) wide distally, 4 (4-5) wide proxi- Scleroductus gen. n. mally, with round upturned "toe." Handle rel- DIAGNOSIS: Gyrodactylidae Cobbold, 1864; atively thick, 16 (16-17) long. Marginal hook Gyrodactylinae Monticelli, 1892. Body elongate filament 15 (15-16) long. with 2 cephalic lobes. Haptor with 16 marginal HOST: Pimelodella yuncensis Steindachner, hooks evenly distributed around lateral and pos- 1912 (Pimelodidae), "Bagre." terior margins of haptor. Bulbous pharynx, short LOCALITY: Tributaries of the Chicama River, esophagus, and intestinal crura ending blindly. Peru, 79°21'16"W longitude, 7°46'54"S latitude. Hamuli slender, with poorly developed deep root. SITE OF INFECTION: Present in body washings. Single superficial and deep bars. Viviparous re- HOLOTYPE: USNM Helm. Coll. No. 80629. production. Bulbous penis with 2 sclerotized ribs PARATYPES: USNM Helm. Coll. Nos. 80630. along length of ejaculatory duct and a sclerotized Scleroductus closely resembles species of Gy- partial ring surrounding the opening. Parasites rodactylus Nordmann, 1832. The haptor con- of freshwater teleosts. tains slender hamuli devoid of a prominent deep TYPE SPECIES: Scleroductus yuncensi. root, a small single superficial bar, and 16 mar- 125 Copyright © 2011, The Helminthological Society of Washington 126 PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY Figures 1-5. Sclerotized body parts of Scleroductus yuncensi gen. et sp. n. from Pimelodella yuncensis Stein- dachner in Peru. The figures are a composite prepared from the holotype and paratypes. 1. Hamulus and superficial bar. 2. Penis in lateral view. 3. Oblique view of flattened penis showing the horseshoe-shaped form of the terminal sclerotized ring and an alternative view of the 2 ribs. 4. Marginal hook. 5. Deep bar. Scale bar = 10 /urn. ginal hooks spaced evenly around the lateral and Anacanthocotyle Kritsky and Fritts, 1970, Ar- posterior margins of the simple disk. Initially we chigyrodactylus Mizelle and Kritsky, 1967, Fun- suspected that the Peruvian material was a mem- dulotrema Kritsky and Thatcher, 1977, Gyrdi- ber of a unique Asian lineage of Gyrodactylus (G. cotylus Vercammen-Grandjean, 1960 (see Harris afghanensis Ergens, 1979, G. luckyi Ergens, 1970, andTinsley, 1987), Gyrodactyloidcs Bychowsky, G. moraveci Ergens, 1979, G. parvus Bychowsky, 1947, Gyrodactylus Nordmann, 1832, Isancis- 1936, and G. tibetanus Dzhalilov, 1981) parasit- trum de Beauchamp, 1912 (see Llewellyn, 1984), izing cypriniform fishes and having the superfi- Laminiscus Palsson and Beverley-Burton, 1983, cial bar membrane as 2 posteriorly directed fil- Macrogyrodactylus Malmberg, 1957, Metagyro- amentous processes (Ergens, 1970, 1979; dactylus Yamaguti, 1963, Paragyrodactylus Dzhalilov, 1981; Gussev, 1985). However, the Gvozdev and Martechov, 1953, Paragyrodac- morphology of the bulbous penis with the scler- tyloides (Szidat, 1973) Ostowskide Nunez, 1975, otized terminal ring and 2 sclerotized ribs within Polyclithrum Rogers, 1967, and Swingleus Rog- the ejaculatory duct proved significantly different ers, 1969. In Afrogyrodactylus Paperna, 1968, from that of all known members of the Gyro- the penis is an elongated muscular tube contain- dactylidea to warrant establishment of a new ge- ing a duct studded with minute rods or spines nus. (Paperna, 1968). In Oogyrodactylus Harris, 1983, Gyrodactylideans most frequently have a pe- the penis is a muscular tube with a basal bulb; nis in the form of a muscular bulb armed with the expressible tip bears a sclerotized ring and varying numbers of small sclerites or spines and gland cells are present distally and basally (Har- a large beaklike sclerite at the opening. Small ris, 1983). In Phanerothecium Kritsky and gland cells can occur at the base of certain of the Thatcher, 1977, the penis is described as an un- sclerites. The duct passing through the penis is armed muscular tube that has a lightly sclero- nonsclerotized, but may be dilated into a saclike tized duct and incorporates a coiled portion of structure. This form is found in the genera the vas deferens (Kritsky and Thatcher, 1977). Copyright © 2011, The Helminthological Society of Washington OF WASHINGTON, VOLUME 56, NUMBER 2, JULY 1989 127 Scleroductus yuncensi is the fourth species of asites of Fish of the Fauna of the USSR. Publishing the Gyrodactylidea to be described from South House "Hayka," Leningrad, U.S.S.R. 424 pp. Harris, P. D. 1983. The morphology and life-cycle American freshwater fishes. The others are of the oviparous Oogyrodactylus farlowellae gen. Oogyrodactylus farlowellae Harris, 1983, from et sp. nov. (Monogenea, Gyrodactylidea). Parasi- body surface of the loricarid siluriform Farlow- tology 87:405-420. ella amazonum imported into Britian; Phanero- , and R. C. Tinsley. 1987. The biology of Gyr- thecium caballeroi Kritsky and Thatcher, 1977, dicotylus gallieni (Gyrodactylidea), an unusual vi- viparous monogenean from the African clawed from the gills of the pimelodid siluriform Cepha- toad, Xenopus laevis. Journal of Zoology 212:325- losilurus zungaro in 2 locations in Colombia; and 346. Paragyrodactyloides superbus (Szidat, 1973) from Kritsky, D. C., and V. E. Thatcher. 1977. Phanero- the callichthyid siluriform Corydoras paleatus thecium gen. nov. and Fundulotrema gen. nov. Two new genera of viviparous Monogenea (Gy- held captive in the Museum of Natural History rodacty loidea) with a description of P. caballeroi in Buenos Aires. Thus, information to date sug- sp. nov. and a key to the subfamilies and genera gests that neotropical representatives of this par- of the family. Exerto Parasitologica en Memoria ticular parasite lineage have successfully radiated del Doctor Edwardo Caballero y Caballero, Insti- among a variety of siluriform fishes. tute de Biologie, Mexico. Pages 53-60. Llewellyn, J. 1984. The biology of Isancistrum subu- latae n. sp., a monogenean parasitic on the squid, Literature Cited Alloteuthis subulata, at Plymouth. Journal of the Marine Biological Association, U.K. 64:285-302. Dzhalilov, U. D. 1981. Gyrodactylus tibetanus sp. n. Malmberg, G. 1970. The excretory systems and the (Monogenea: Gyrodactylidae), a new fish parasite marginal hooks as a basis for the systematics of from Tajikistan. Folia Parasitologia 28:88. Gyrodactylus (Trematoda, Monogenea). Arkiv for Ergens, R. 1970. Monogenoidea from fishes of the Zoologi 23:1-235. genus Noemacheilus (Cobitidae) from Mongolia. Mizelle, J. D., and D. C. Kritsky. 1967. Studies on Folia Parasitologica 17:285-291. monogenetic trematodes. XXX. Five new species . 1979. Two new species of the genus Gyro- of Gyrodactylus from the Pacific tomcod, Micro- dactylus Nordmann, 1832 (Gyrodactylidae: gadus proximus (Girard). Journal of Parasitology Monogenoidea) from Afghan fishes. Folia Paras- 53:263-269. itologica 26:77-79. Paperna, I. 1968. Monogenetic trematodes collected Gussev, A. V. 1985. Multicellular parasites (part one). from freshwater fish in Ghana. Second Report. In O. N. Bauer, ed. Handbook for Identifying Par- Bamidgeh 20:88-96. Copyright © 2011, The Helminthological Society of Washington.