Paraorygmatobothrium taylori n. sp. (Tetraphyllidea ...

56 Syst Parasitol (2009) 74:49–58bothridial muscle bands and distinctive features sharedwith the other 10 described Paraorygmatobothriumspecies: serrate spinitriches and filitriches covering theproximal bothridial surfaces, a scutellate neck withscutes consisting of filitriches, and bothridia with asingle loculus and a single apical sucker. We followRuhnke (1994) in choosing to heavily weight themultiple characteristics these two species share withthe other 10 described species of Paraorygmatobothriumand do not propose a separate generic status forParaorygmatobothrium species possessing bothridialmuscle bands. In addition to the features shared withall other Paraorygmatobothrium species, P. taylorialso possesses distinctive features that affiliate it withthe other two species of the genus described fromhemigaleid sharks. This new taxon possesses acephalic peduncle and vitelline follicles that extendalmost to the mid-line of the proglottis and arereduced, rather than interrupted, at the level of theovary. Both of these features are shared with P. janineaeand P. kirstenae (see Ruhnke et al., 2006).Ruhnke et al. (2006) noted that these features couldwarrant a separate generic status for P. janineae andP. kirstenae, just as the bothridial muscle bands ofP. barberi, but we choose to focus on the characteristicsthat P. taylori, P. janineae and P. kirstenaeshare with the nine other species of Paraorygmatobothrium,and do not propose the separation of thesethree species.Paraorygmatobothrium taylori appears to berestricted to one host shark species, Hemigaleusaustraliensis. Detailed examination of the spiralintestines of 11 other carcharhiniform species fromthe same geographical area yielded only a singlespecimen of P. taylori, found in an adult snaggletoothshark Hemipristis elongata. This specimen wasimmature and it is considered here that this singlespecimen does not justify the formal recoding ofH. elongata as a host for P. taylori. The specimenhas been lodged in the Queensland Museum (QM G231308). High host-specificity is typical for speciesof Paraorygmatobothrium, with each described speciesbeing recorded from only a single shark species(Ruhnke, 1994; Ruhnke, 1996; Ruhnke et al., 2006;Ruhnke & Thompson, 2006; Ruhnke & Carpenter,2008). The possible exception is P. kirstenae, whichmay occur in two hemigaleid sharks of the samegenus. Ruhnke et al. (2006) described P. kirstenaefrom Hemigaleus microstoma, noting the type-localityas off Mukah, Sarawak, Malaysia in the SouthChina Sea and an additional locality as off theNorthern Territory, Australia, in the Arafura Sea. Ataxonomic revision of Hemigaleus Bleeker occurredat about the same time with the proposal of theAustralian weasel shark H. australiensis as a fullspecies in Australian waters, while H. microstomawas retained over the rest of its former range (Whiteet al., 2005). Thus, it is likely that P. kirstenae occursin both H. microstoma (type-host) in the South ChinaSea and H. australiensis off Northern Australia.Conceivably, the specimens on which P. kirstenaewas described may constitute two species, one foundin H. microstoma and one in H. australiensis.Paraorygmatobothrium taylori may provide anexcellent opportunity to match a second intermediatestage (metacestode) to an adult worm. Metacestodesof tetraphyllideans, especially phyllobothriids, aremorphologically very similar, typically only beingidentifiable to type groups (Chambers et al., 2000).To date, there are few published data on matchingtetraphyllidean life-cycles, with some studies utilisingmorphological (e.g. Hamilton & Byram, 1974;Cake, 1976; Carvajal et al., 1982; Chambers et al.,2000) and molecular techniques (e.g. Brickle et al.,2001; Agustí et al., 2005; Aznar et al., 2007) to helpmatch metacestodes to adult genera. Taylor &Bennett (2008) found that Hemigaleus australiensisis a specialist feeder, with a diet comprising about95% cephalopod molluscs by prey number. On thebasis of the weasel shark’s restricted diet, we predictthat the metacestodes of P. taylori will be found inOctopodidae, Sepiolidae, Sepiidae or Loliginidae inwaters off south-east Queensland.The specimens found in Hemipristis elongatafrom Moreton Bay possess key diagnostic characteristicsof P. janineae: a cephalic peduncle coveredwith serrate spinitriches and vitelline follicles thatextend almost to the mid-line of the proglottis and arereduced at the level of the ovary. The shape and sizeof the bothridia differ from the original description ofP. janineae, but these differences are attributed hereto differences in the method of fixation. Specimensfrom Moreton Bay were heat-fixed in near-boilingvertebrate saline before being preserved in 10%formalin, whereas the specimens from Ruhnke et al.(2006) were fixed at room temperature in 10%123