Trypanorhynch cestodes (Platyhelminthes) parasitic in elasmobranchs and crustaceans in Moreton Bay, Queensland

Abstract

Examination of 64 elasmobranchs comprising 13 species from Moreton Bay yielded 13 identifiable species of cestodes of the order Trypanorhyncha Diesling, 1863. Two new species, Dollfusiella armata sp. nov. from Maculabatis toshi (Whitley, 1939) and M. cf. astra Last, ManjajiMatsumoto and Pogonoski, 2008, and Dollfusiella pilosa sp. nov. from Aetobatus ocellatus (Kuhl, 1823) are described. Prochristianella odonoghuei Beveridge, 1990 becomes a junior synonym of Prochristianella butlerae Beveridge, 1990 based on identical strobilar and tentacular morphologies. Prochristianella omunae Beveridge and Justine, 2010 is reported from Australia for the first time, where it was recovered from the type host Neotrygon trigonoides (Castelnau, 1873). Additional new host records are included as well as extensions of known geographical distributions to now include south-eastern Queensland. Metacestodes were recovered from the digestive glands of yabbies, Trypaea australis (Dana, 1852), representing an undescribed species of Dollfusiella. Adults of this species were found in the spiral valves of N. trigonoides and Ae. ocellatus. Six species of metacestodes of trypanorhynch cestodes were recovered from the digestive glands of pistol shrimps, Alpheus spp. (A. richardsoni Yaldwyn, 1971 and A. papillosus Banner & Banner, 1982). Of these, three were identified as Parachristianella monomegacantha Kruse, 1959, Prochristianella aciculata Beveridge and Justine, 2010 and Zygorhynchus robertsoni Beveridge and Campbell, 1988, the adults of all three species being originally reported from batoids. Two undescribed species of Dollfusiella and undescribed species of Parachristianella and Zygorhynchus were also recovered from alpheid shrimps; definitive hosts were identified for each species, but the material available was insufficient to allow formal descriptions.  Cestoda, Trypanorhyncha, elasmobranchs, Callianassidae, Alpheidae, life cycles, new species. Beveridge, I. & Shaeffner, B.C. 110 Memoirs of the Queensland Museum | Nature  2018  61 limited to date. Beveridge (1990) reported a number of species of eutetrarhynchids from batoids in Moreton Bay, while Beveridge and Campbell (1988a) described Shirleyrhynchus butlerae Beveridge and Campbell, 1988 from Hemitrygon fluviorum (Ogilby, 1908) and recorded Callitetrarhynchus gracilis (Rudolphi, 1819) from the same host species (Beveridge & Campbell 1996). Palm and Beveridge (2002) also reported tentaculariid trypanorhynchs from elasmobranchs and teleosts both within Moreton Bay and from the oceanic coast of North Stradbroke Island. However, there has been no systematic collecting of trypanorhynch cestodes in this region to date. The current report is part of an examination of the trypanorhynch fauna of Moreton Bay, Queensland. In an earlier publication, the larval trypanorhynch species in teleost fishes were reported (Beveridge et al. 2017a). In this paper, we report the adult species of trypanorhynchs encountered in elasmobranchs from Moreton Bay together with limited observations on intermediate stages present in crustaceans. MATERIALS AND METHODS Elasmobranchs, mainly batoid rays, were collected from a commercial fishery in Moreton Bay in November 2011, and January and June 2016. Photographs and/or tissue samples were collected from each fish to confirm identifications if necessary. Host specimens were identified primarily using the keys and descriptions in Last and Stephens (2009). In the case of any elasmobranchs whose identity was uncertain, entire specimens were deposited in the Queensland Museum (QM). Elasmobranch host nomenclature follows Last et al. (2016). In instances where host names have changed since the original publication, the original name is also cited in the text. Authorities for elasmobranch species listed in Table 1 are not repeated in the text. Collection localities within Moreton Bay are shown in Fig. 1. To avoid repetition, localities mentioned in the text are assumed to be within Moreton Bay. Spiral valves were opened along the dorsal midline. Representative cestodes visible were removed and placed on microscope slides in saline. A cover slip was placed over them and pressure was applied to the coverslip with fine forceps to force the eversion of tentacles. The specimens were flooded with 70% ethanol while maintaining pressure to keep the tentacles everted. Once fixed, the cestodes were stored in ethanol. The remaining spiral valve and its contents were flooded with hot saline, followed immediately with either 70% ethanol or 10% formalin. Spiral valves fixed in formalin were subsequently transferred to 70% ethanol for storage. Cestodes were removed from spiral valves and stored in 70% ethanol. Some scoleces with everted tentacles were mounted in Hoyer’s medium. Entire cestodes were stained in Celestine Blue, destained in 70% acid alcohol, dehydrated in an ethanol series, cleared in methyl salicylate and mounted in Canada balsam. Specimens selected for scanning electron microscopy were dehydrated in ethanol, transferred to hexamethyl disilazane and allowed to dry. They were mounted on stubs with carbon tape, coated with gold and examined using a FEI Nova NanoSEM 450 FEG field emission gun scanning electron microscope using an accelerating voltage of 3-10 Kv. Microthrix terminology follows Chervy (2009). Crustaceans (Trypaea australiensis Dana, 1852, Alpheus richardsoni Yaldwyn, 1971 and Al. papillosus Banner & Banner, 1982) were collected at low tide on mud flats at Wynnum (November 2011) and Dunwich (May 2010, January and June 2016) in areas where batoids feed at high tide. Localities are shown in Fig. 1. Each crustacean was dissected individually, any metacestodes present in the digestive glands were placed on a microscope slide in saline, pressure was applied to a coverslip to evert tentacles and then the slide was flooded with 70% ethanol. Subsequently, metacestodes were stored in 70% ethanol and were mounted in a similar fashion to the adult cestodes. Several heavily infected digestive glands were fixed in 10% neutral buffered formalin. They were then embedded in paraffin and sectioned at a thickness of 5 μm. Sections were stained with haematoxylin and eosin. Trypanorhynch cestodes (Platyhelminthes) Memoirs of the Queensland Museum | Nature  2018  61 111 Several species of crabs collected at Wynnum were also examined for metacestodes. These comprised 11 Metopograpsus frontalis Miers, 1880, 3 Ancylocheles gravelei (Sankolli, 1963), 1 Leptodius exeratus (H. Milne Edwards, 1834) and 1 Macromedaeus crassimanus (H. Milne Edwards, 1867). All cestode specimens collected have been deposited either in the QM or in the South Australian Museum, Adelaide (SAM). Terminology for the anatomical features of the cestodes follows Pintner (1913) and Dollfus (1942). The names of the genera Parachristianella Dollfus, 1946 and Prochristianella Dollfus, 1946 are abbreviated as ‘Para.’ and ‘Pro.’ respect ively to avoid confusion. Measurements are included for species in which they provide novel information. Measurements were made with an ocular micrometer and are presented in millimetres unless otherwise indicated. In instances where only one or two specimens were available, individual measurements are provided. In cases where additional specimens were available, the measurements are presented as the range followed, in parentheses, by the mean and the number of specimens measured. In the case of the tentacular armature of very small species, at the limits of resolution of the light microscope and without specimens suitably cleaned for scanning electron microscopy, photographs of the tentacles were taken and measurements were made from the photographs. In these instances, measurements are presented in micrometers, to one decimal point of accuracy. Identifications of known species are supported by confirmatory illustrations and measurements wherever possible. Instances in which this has not been possible are indicated. The extent of morphological information included in current descriptions depended upon the completeness of information already published. Essentially, additional morphological information has been provided only in instances where it contradicts or adds to data already published. Trypanorhynch taxonomy at the superfamily level follows Palm (2004). Family level nomenclature is either unstable or under question (Beveridge et al. 2017b) and therefore only superfamily and generic allocations are