Insights from new cestodes of the crocodile shark,Pseudocarcharias kamoharai(Lamniformes: Pseudocarchariidae), prompt expansion ofScyphyophyllidumand formal synonymization of seven phyllobothriidean genera – at last!

Abstract

Three new cestode species are described from the crocodile shark (Pseudocarcharias kamoharai) in Ecuador. All three were examined with light and scanning electron microscopy. The unique combination of morphological features in one of the new species prompted formal investigation of the non-monophyly of Paraorygmatobothrium relative to the morphologically similar genera Doliobothrium, Guidus, Marsupiobothrium, Nandocestus, Orectolobicestus, Ruhnkecestus and Scyphophyllidium. Sequence data generated for part of the 28S rDNA gene were subjected to maximum likelihood (ML) analysis. The resulting tree led to the synonymization of six of these seven genera with Scyphophyllidium, and transfer of their species to the latter genus. With the new species, the number of described members of Scyphophyllidium is now 45. The diagnosis of Scyphophyllidium is revised to accommodate these species. In addition, to expedite future descriptions, eight categories of Scyphophyllidium species are circumscribed, based largely on bothridial features. Scyphophyllidium timvickiorum n. sp. is a category 1 species. Beyond being the smallest category 1 species, it bears, rather than lacks, apical suckers and lacks, rather than bears, strobilar scutes. The two other new species are members of Clistobothrium. Clistobothrium amyae n. sp. differs from its congeners in bothridial shape, elongate cephalic peduncle and tiny size. Clistobothrium gabywalterorum n. sp. differs from the two of its congeners that also possess foliose bothridia in overall size and testis number. Despite their substantial morphological differences, the ML tree indicates they are sister taxa. Both are unique among their congeners in possessing cephalic peduncle spinitriches. The diagnosis of Clistobothrium is revised accordingly.

Molecular Characterization of Clistobothrium sp. Viable Plerocercoids in Fresh Longfin Inshore Squid (Doryteuthis pealeii) and Implications for Cephalopod Inspection

“…The LSU was selected as elective target for the analysis, as it is the most used molecular marker for identifying Cestoda [ 3 , 26 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ], sometimes in combination with the small subunit (SSU) rRNA gene [ 39 , 40 , 41 ]. Although Olson et al [ 40 ] indicated that the D2 region of the LSU gene exhibited sufficient variability to be useful for species-level identification, a low interspecies variability has been reported by other authors [ 35 ], and other genes, such as COI and ITS, were proposed as alternative markers for distinguishing closely related species of Phyllobothriidae [ 35 , 42 , 43 ].…”

“…Until recently, only three species were reported in the genus Clistobothrium : C. montaukensis , C. carcharodoni and C. tumidum [ 44 ]. However, Caira et al [ 34 ] have very recently described two new species ( C. amyae and C. gabywalterorum ) and suggested an expansion of the total number to six, including the undescribed species C. cf. montaukensis reported by Brickle et al [ 3 ] and Randhawa and Brickle [ 36 ].…”

“…This cluster was separated from other Clistobothrium species, in particular C. carcharodoni , C. montaukensis and sequences of two newly described species of Clistobothrium sp. ( C. amyae and C. gabywalterorum ) [ 34 ], as well as from the other Phyllobothriidae species which showed an identity value higher than 99% in the BLAST analysis. Thus, the larvae found in the present study can be assigned to the genus Clistobothrium, possibly to the same undescribed species reported by Brickle et al [ 3 ] and by Randhawa and Brickle [ 36 ] or maybe to another still undescribed species.…”

“…merocercoids were found in seals, and tentatively attributed to C. tumidum on the basis of bothridial morphology. However, further molecular analysis, ideally investigating also adult specimens, would be needed [ 35 ], also considering that the taxonomy of tetraphyllidean and phyllobothridean has undergone major revision [ 34 , 38 , 46 ]. In fact, the Phyllobothriidae family, which was traditionally included in the Tetraphyllidea order, was recently elevated to ordinal status [ 25 , 30 ].…”

“…The edited sequences were used to run a BLAST analysis on GenBank, selecting the Somewhat similar sequences (blastn) algorithm. Then, genera of the Phyllobothridae family were searched on the World Register of Marine Species database [ 57 ] and also in the most recent works dealing with Phyllobothriidea taxonomy [ 25 , 34 , 38 ]. Subsequently, for all the retrieved genera, all the available LSU sequences were searched on GenBank ( ) to create a genetic dataset, as detailed in Table S1 .…”