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.
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Phylogenetic relationships, host associations, and three new species of a poorly known group of “tetraphyllidean” tapeworms from elasmobranchs
This paper aims to expand understanding of a poorly known group of cestodes that parasitize an intriguingly diverse suite of elasmobranchs. The group’s three currently described members (i.e., Pentaloculum macrocephalum, Pentaloculum hoi, and Zyxibothrium kamienae) parasitize an electric ray, a carpet shark, and a skate, respectively. Pentaloculum grahami n. sp. is described from a second genus of carpet shark, specifically Parascyllium collare, in Australia. Zyxibothrium duffyi n. sp. and Zyxibothrium healyae n. sp. are described from the deep-sea skates Brochiraja asperula and Brochiraja spinifera, respectively off New Zealand. The three new species share distinctive bothridia that bear a small number of large, circular, facial loculi and lateral bands of vitelline follicles that converge posterior to the ovary—features which are found in all other members of these genera. Zyxibothrium healyae n. sp. is unique in possessing three, rather than four or five, facial loculi. Zyxibothrium duffyi n. sp. possesses a combination of five facial loculi and vitelline follicles that stop short of the anterior margin of the proglottid. Pentaloculum grahami n. sp. is the largest member of the group with the greatest number of proglottids. Based on striking similarities in scolex morphology, Pentaloculum and Zyxibothrium have been hypothesized to belong to a distinct subgroup of “tetraphyllideans” provisionally designated as Clade 1. Based on sequence data for the D1–D3 region of the 28S rDNA gene generated for species of Zyxibothrium for the first time, we confirm the reciprocal monophyly of both genera as well as the monophyly of Clade 1 and its status as a distinct lineage among the “Tetraphyllidea”. This work also suggests that the presence of five facial loculi is homoplasious given this character state is found in members of both genera. The new species expand the host associations of Clade 1 to include additional skate and carpet shark genera. Moving forward we would expect to find additional members of this group parasitizing other species of parascyliid carpet sharks as well as other species of the rajid genus Malacoraja and the arhynchobatid genus Brochiraja. Here we have doubled the number of described species in the taxon referred to as Clade 1 while simultaneously expanding our understanding of the morphology and anatomy of its members. This additional information will help inform the ultimate revision of the ordinal classification of the cestodes to address the highly polyphyletic nature of the order “Tetraphyllidea” as it is currently configured.
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- NSF-PAR ID:
- 10448715
- Date Published:
- Journal Name:
- Zootaxa
- Volume:
- 5254
- Issue:
- 1
- ISSN:
- 1175-5326
- Page Range / eLocation ID:
- 30 to 50
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.11646/zootaxa.5254.1.2
