RESEARCH EVOLVED A NEW GENUS AND SPECIES OF MACRODEROIDIDAE, AND OTHER DIGENEANS FROM FISHES OF LAKE MALAWI, AFRICA Author(s): Rodney A. Bray and Sherman S. Hendrix Source: Journal of Parasitology, 93(4):860-865. Published By: American Society of Parasitologists DOI: http://dx.doi.org/10.1645/GE-1084.1 URL: http://www.bioone.org/doi/full/10.1645/GE-1084.1 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms of use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. J. Parasitol., 93(4), 2007, pp. 860-865 © American Society of Parasitologists 2007 A NEW GENUS AND SPECIES OF MACRODEROIDIDAE, AND OTHER DIGENEANS FROM FISHES OF LAKE MALAWI, AFRICA Rodney A. Bray and Sherman S. Hendrix* Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom. e-mail: [email protected] a b s t r a c t : Malawitrema staufferi n. gen., n. sp., an unusual digenean, is described from Clarias mossambicus (type host) and Bagrus meridionalis from Lake Malawi. It has a small, pyriform body, with a spinous tegument. The ceca are relative short, not reaching to the testes. The 2 testes are symmetrical in the middle hind body. The cirrus sac is long and narrow, reaching into hind body. The genital pore is median, immediately anterior to the ventral sucker. The ovary is pretesticular, and a canalicular seminal vesicle and Laurer’s canal are present. The uterus usually reaches distinctly posteriorly to testes. The eggs are small. The follicular vitellarium is in 2 small fields just anterior to testes. The ventrally subterminal excretory pore leads to a claviform vesicle. This species does not fit clearly into any known family of digeneans and is placed in the Macroderoididae as a temporary measure. Other digeneans reported from Lake Malawi include Haplorchoides cahirinus (Looss, 1896) in C. mossambicus and B. meridionalis; Astiotrema turneri Bray, van Oosterhout, Blais & Cable, 2006 in Protomelas annectens, P. cf. taeniolatus, Labeo- tropheus fuelleborni, Ctenopharynx (Otopharynx) pictus, and Pseudotropheus zebra; Glossidium pedatum Looss, 1899 in C. mossambicus and B. meridionalis; and an unidentifiable sanguinicolid from Bathyclarias nyasensis. Little is known of the digenean fauna of Lake Malawi (for­ Taxonomic summary merly Lake Nyasa). Prudhoe (1957) reported the metacercaria Type species: Malawitrema staufferi n. sp. of Clinostomoides brieni Dollfus, 1950 in Clarias sp., Taylor Etymology: The genus is named after the lake in which it is found. et al. (1998) mentioned unnamed digeneans in haplochromine cichlids, and Bray et al. (2006) recently described a new Astio- Remarks trema species from mbuna cichlids. The present article adds to This species on which this genus is based is not identifiable as any that small data set by reporting 5 species of adult digeneans, of those in Khalil and Polling (1997). In fact, it is difficult to place this including a puzzling new form from siluriforms. form into a currently recognized family; placing the new species in the Macroderoididae is considered a temporary measure until further evi­ dence is available. Using the fish parasite keys in Yamaguti (1971) MATERIALS AND METHODS positions it in either Fellodistomidae Nicoll, 1909 or the Lecithoden- driidae Odhner, 1910. The Fellodistomidae is a predominantly marine Fishes were captured by hook and line, transported alive to the work family, and is characterized by an unarmed tegument, a uterine seminal area, and necropsied within 4 hr of capture. Individual sections of the receptacle, and a Y- or V-shaped excretory vesicle. Clearly, M. staufferi digestive system were examined separately, and all worms were killed does not belong in this family. As far as the Lecithodendriidae is con­ in hot water and fixed in alcohol-formalin-acetic acid (AFA). Whole cerned, a few species of the predominantly amphibian, Ganeo Klein, mounts were stained with Mayer’s paracarmine, cleared in beechwood 1905 and Pleurogenoides Travassos, 1921, are reported in freshwater creosote, and mounted in Canada balsam. Measurements were made fishes in India and Bangladesh, but the present specimen does not look through a drawing tube on an Olympus BH-2 microscope, with the use anything like species in either of these genera with their Y-shaped ex­ of a Digicad plus digitizing tablet and Carl Zeiss KS100 software adapt­ cretory vesicles and lateral genital pores. Nevertheless, according to ed by Imaging Associates, and are quoted in micrometers. The material Yamaguti (1971), a few lecithodendriids are reported as having cylin­ is lodged in the BMNH collection of the Natural History Museum, drical or saccular excretory vesicles, and not all species have lateral London, United Kingdom. genital pores. With the use of the keys and diagnoses in the series by Gibson et al. DESCRIPTION (2002), Jones et al. (2005), and in Schell (1985), it appears that the short ceca suggest affinities with the Brachycoeliidae. Although some brachy- Malawitrema n. gen. coeliids are said to have a Y-shaped excretory system, Brachycoelium Du- jardin, 1845 and Cymatocarpus Looss, 1899 have either an I-shaped ex­ Diagnosis cretory vesicle, or a Y-shaped vesicle with a long stem and ‘‘short incon­ Macroderoididae McMullen, 1937. Body small, pyriform. Eye spot spicuous branches’’ (Prudhoe and Bray, 1982; T. Pojmaiiska, pers. comm.). pigment granules in forebody. Tegument spinous. Oral sucker subglobu- The Brachycoeliidae is reported as occurring only in amphibians, reptiles, lar, subterminal. Ventral sucker rounded, slightly pre-equatorial. Pre­ and, rarely, mammals, so the finding of a brachycoeliid in a fish would be pharynx short. Pharynx small, subglobular. Esophagus distinct. Intesti­ highly unusual. Malawitrema differs from well-established members of the nal bifurcation in posterior forebody. Caeca blind, narrow, reaching to Brachycoeliidae (see Schell, 1985) by the caeca reaching almost to the level of vitelline fields. Testes 2, rounded to oval, margins smooth, testes, the restricted vitelline distribution in the hind body, and the relatively symmetrical in middle hind body, separated, not contiguous. Cirrus sac short, claviform excretory vesicle. long, narrow, reaching into hind body. Internal seminal vesicle long. When Bray et al. (2006) described a new species of Astiotrema Pars prostatica long, wide. Ejaculatory duct short. Genital atrium dis­ Looss, 1900 from freshwater fishes in Lake Malawi, they considered tinct. Genital pore median, immediately anterior to ventral sucker. Ova­ that there were 4 nominal plagiorchiid-like genera in freshwater fishes ry oval, pretesticular, overlapping ventral sucker, separated from testes in Africa, i.e., Astiotrem a, Glossidium Looss, 1899, Alloglossidium Sim- by uterus. Canalicular seminal vesicle and Laurer’s canal present. Uterus er, 1929, and Afromacroderoides Khali, 1972. Malawitrema is not sim­ intercecal usually reaches distinctly posteriorly to testes. Eggs small. ilar to any of them; they all have longer caeca, more extensive vitelline Vitellarium follicular; in 2 small fields laterally, mainly just anterior to fields and tandem to oblique testes. McMullen (1937) erected the family testes. Excretory pore ventrally subterminal. Vesicle claviform, reaching Macroderoididae McMullen, 1937, for the plagiorchioids from fishes just anteriorly to testes. and differentiated it from the Plagiorchiidae by its I-shaped (as opposed to Y-shaped) excretory vesicle. Macroderoidids were, at this time, thought to be only in the digestive tract of fishes. This is still the case Received 4 October 2006; revised 24 January 2007; accepted 25 Jan­ for the type genus, Macroderoides Pearse, 1924, but not for all the other uary 2007. genera subsequently placed in the family, such as Alloglossidium , which * To whom correspondence should be addressed. Department of Biol­ is also found in leeches and crustaceans (Brooks, 2003). Nevertheless, ogy, Gettysburg College, Gettysburg, Pennsylvania 17325. several plagiorchiid-like genera from fishes have been considered mem­ 860 BRAY AND HENDRIX— M. STAUFFERI, N. GEN., N. SP., FROM LAKE MALAWI 861 bers of the Macroderoididae, including the marine form Cirkennedya Gibson & Bray, 1979. The constituent genera of the Macroderoididae, and thus of other plagiorchioid families, are the subject of dispute, par­ ticularly as the shape of the excretory vesicle is often difficult to dis­ tinguish or is poorly described. Molecular studies are now being utilized to elucidate the relationships of the plagiorchioid genera and families. These results indicate that Macroderoides is a plagiorchioid genus, but not especially close to the Plagiorchiidae (Tkach, Snyder, and Swider- ski, 2001; V. Tkach, pers.