Yamaguticestus squali Caira &amp; Bueno &amp; Jensen 2021
Creators: name: Caira, Janine N.
name: Bueno, Veronica
name: Jensen, Kirsten
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Cestoda
Phyllobothriidea
Phyllobothriidae
Yamaguticestus
Yamaguticestus squali

description: <i>YAMAGUTICESTUS SQUALI</i> (YAMAGUTI, 1952) COMB. NOV. BASIONYM: <i>PHYLLOBOTHRIUM SQUALI</i> YAMAGUTI, 1952 (FIG. 5A–E) The following details of the surface features on the scolex of this species, based on examination of a specimen with SEM collected from the type host near the type locality, expand the original description of this species by Yamaguti (1952) and the redescription based on the holotype by Vasileva <i>et al.</i> (2002). Anterior-most regions of bothridia densely covered with capilliform filitriches (Fig. 5B). Distal surfaces of loculus densely covered with gongylate columnar spinitriches and capilliform spinitriches (Fig. 5C); distal surfaces of apical sucker not observed. Proximal bothridial surfaces densely covered with capilliform filitriches (Fig. 5D). Cephalic peduncle lacking. Neck (Fig. 5E) and strobila with capilliform filitriches arranged in wide scutes. <i>Synonyms:</i> <i>Phyllobothrium squali</i> Yamaguti, 1952; <i>Crossobothrium squali</i> (Yamaguti, 1952) Williams, 1968. <i>Type host:</i> Pacific spiny dogfish, <i>Squalus suckleyi</i> (Girard, 1855), (Squaliformes: Squalidae de Blainville). <i>Additional hosts:</i> None. <i>Type locality:</i> Pacific Ocean, off Onahama, Hukusiima Prefecture, Japan. <i>Additional localities:</i> Sea of Japan, off Oga City, Akita Prefecture, Japan (39°46′55.8″N, 139°51′49.2″E) (JN- 67); eastern Pacific Ocean, off Bamfield, Vancouver Island, Canada (48°50′7.9152″N, 125°08′7.7208″W). <i>Site of infection:</i> Spiral intestine. <i>Material examined:</i> One specimen examined with SEM collected from a shark collected off the west coast of Japan. <i>Sequence data:</i> GenBank accession MW 419975, hologenophore (BAM 5-wP9) LRP no. 8674. <i>Remarks:</i> By erecting the genus <i>Yamaguticestus</i>, we have established a more appropriate home for the species formerly referred to as <i>Phyllobothrium squali</i>. The transfer of this species from <i>Phyllobothrium</i>, as <i>Yamaguticestus squali</i>, resolves the issue of the nonmonophyly of <i>Phyllobothrium</i> that has been raised by a number of previous authors (e.g. Ruhnke, 2011; Caira <i>et al.</i>, 2014). However, issues surrounding the identity of <i>Y. squali</i> remain. It was originally described by Yamaguti (1952) from a host identified as the Pacific spiny dogfish (<i>Squalus suckleyi</i> as <i>Squalus suckleyii</i>) off the eastern coast of Japan. Vasileva <i>et al.</i> (2002) subsequently provided a thorough redescription of this species based on examination of the holotype, in which they included illustrations of the scolex and details of the terminal genitalia for the first time. However, this species has also been reported from sharks identified as the piked dogfish (<i>Squalus acanthias</i>) from a variety of other localities globally, including the north-eastern Atlantic Ocean in the Bay of Biscay off Concarneau, France (Euzet, 1959) and the Irish Sea (McCullough &amp; Fairweather, 1983; McCullough <i>et al.</i>, 1986), the western Atlantic Ocean off Rhode Island, USA (Pickering &amp; Caira, 2012; Ruhnke &amp; Workman, 2013; Caira <i>et al.</i>, 2014) and the Black Sea (Vasileva <i>et al.</i>, 2002). Given the relatively strict degree of host specificity seen in most groups of elasmobranch-hosted cestodes (Caira &amp; Jensen, 2014), reports from two different host species would normally have warranted closer scrutiny. However, the situation was confounded by the fact that <i>Squalus suckleyi</i> has been considered a junior synonym of <i>Squalus acanthias</i> for decades (see Compagno, 1984), and this synonymy has been embraced by many of those working with <i>P. squali</i> previously. For example, Vasileva <i>et al.</i> (2002) listed <i>Squalus acanthias</i> as the type host of <i>P. squali</i>, and Pickering &amp; Caira (2012) referred to the cestodes of <i>Squalus acanthias</i> off Rhode Island as <i>P. squali</i> because <i>Squalus acanthias</i> was the accepted identity of the type host of this cestode species at that time. The relatively recent application of molecular methods to help inform elasmobranch identifications has led to a more careful assessment of the identities and distributions of species of <i>Squalus</i> Linnaeus, 1758 globally (Ebert <i>et al.</i>, 2010). One of the results of that work was the resurrection of the name <i>Squalus suckleyi</i> for the species that occurs in the northern Pacific Ocean and is both molecularly and morphologically distinct from <i>Squalus acanthias</i>, which is now considered to be restricted to the Atlantic Ocean and the southern portions of the Pacific Ocean. Thisrevisedhosttaxonomyhasprofoundimplications for the taxonomy of <i>P. squali</i>. The type host of <i>P. squali</i> is <i>Squalus suckleyi</i>, but the shark specimens reported to host this cestode species off Rhode Island, France and Ireland and in the Mediterranean and Black Seas are <i>Squalus acanthias</i>. This causes us to revisit the question of the conspecificity of the cestodes reported from <i>Squalus suckleyi</i> and <i>Squalus acanthias</i>. Although Vasileva <i>et al.</i> (2002) found their worms from the Black Sea (and thus from <i>Squalus acanthias</i>) generally to be consistent with the morphology of the holotype of <i>P. squali</i> (from <i>Squalus suckleyi</i>), they reported the worms from the Black Sea to be substantially larger than the holotype from <i>Squalus suckleyi</i> off Japan (i.e. 214–603 vs. 141 mm). Also interesting is the fact that the bothridia of the worm identified as <i>P. squali</i> taken from <i>Squalus acanthias</i> in the Irish Sea and examined with SEM by McCullough &amp; Fairweather (1983: fig. 9) are more folded than those of the specimen of <i>P. squali</i> from <i>Squalus suckleyi</i> off Japan examined here (Fig. 5A). These differences led us to begin to question the conspecificity of material from these two host species and thus to advocate that the concept of <i>P. squali</i> be limited to information taken from specimens parasitizing <i>Squalus suckleyi</i> in the northern Pacific Ocean. More detailed comparisons between that material and specimens collected from <i>Squalus acanthias</i> in localities throughout the Atlantic Ocean and its adjacent water bodies are required to assess whether specimens from the two host species and their associated localities are conspecific. Until that time, specimens from <i>Squalus acanthias</i>, including those of Ruhnke &amp; Workman (2013) and Caira <i>et al.</i> (2014) for which sequence data were generated, should be referred to as <i>Yamaguticestus</i> cf. <i>squali</i>. As noted by Vasileva <i>et al.</i> (2002), the material from the velvet belly shark <i>Etmopterus spinax</i> (Linnaeus, 1758), which Euzet (1959) identified as <i>Crossobothrium squali</i>, differs from <i>Y. squali</i> in a number of respects. We believe this material is likely to represent an undescribed species of <i>Yamaguticestus</i>, the formal description of which requires examination of additional material.
description: Published as part of <i>Caira, Janine N., Bueno, Veronica &amp; Jensen, Kirsten, 2021, Emerging global novelty in phyllobothriidean tapeworms (Cestoda: Phyllobothriidea) from sharks and skates (Elasmobranchii), pp. 1336-1363 in Zoological Journal of the Linnean Society 193</i> on pages 1348-1350, DOI: 10.1093/zoolinnean/zlaa185, http://zenodo.org/record/5753537
description: {"references": ["Yamaguti S. 1952. Studies on the helminth fauna of Japan. Part 49. Cestodes of fishes, II. Acta Medicinae Okayama 8: 1 - 76.", "Vasileva GP, Dimitrov GI, Georgiev BB. 2002. Phyllobothrium squali Yamaguti, 1952 (Tetraphyllidea, Phyllobothriidae): redescription and first record in the Black Sea. Systematic Parasitology 53: 49 - 59.", "Williams HH. 1968. Phyllobothrium piriei sp. nov. (Cestoda: Tetraphyllidea) from Raja naevus with a comment on its habitat and mode of attachment. Parasitology 58: 929 - 937.", "Ruhnke TR. 2011. A monograph on the Phyllobothriidae (Platyhelminthes, Cestoda). Bulletin of the University of Nebraska State Museum 25: i - xii, 1 - 208.", "Euzet L. 1959. Recherches sur les cestodes tetraphyllides des selaciens des cotes de France. Unpublished Docteur des Sciences Naturelles Thesis, Universite de Montpellier.", "McCullough JS, Fairweather I. 1983. A SEM study of the cestodes Trilocularia acanthiaevulgaris, Phyllobothrium squali and Gilquinia squali from the spiny dogfish. Zeitschrift fur Parasitenkunde 69: 655 - 665.", "McCullough JS, Fairweather I, Montgomery WI. 1986. The seasonal occurrence of Trilocularia acanthiaevulgaris (Cestoda: Tetraphyllidea) from spiny dogfish in the Irish Sea. Parasitology 93: 153 - 162.", "Pickering M, Caira JN. 2012. A new hyperapolytic species, Trilocularia eberti sp. n. (Cestoda: Tetraphyllidea), from Squalus cf. mitsukurii (Squaliformes: Squalidae) off South Africa with comments on its development and fecundity. Folia Parasitologica 59: 107 - 114.", "Ruhnke TR, Workman RE. 2013. Two new species and a new phyllobothriid cestode genus from sharks of the genus Negaprion Whitley (Carcharhiniformes). Systematic Parasitology 85: 37 - 48.", "Compagno LJV. 1984. FAO Species Catalogue, Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1. Hexanchiformes to Lamniformes. FAO Fisheries Synopsis 125: 1 - 249.", "Ebert DA, White WT, Goldman KJ, Compagno LJV, Daly - Engel TS, Ward RD. 2010. Resurrection and redescription of Squalus suckleyi (Girard, 1854) from the North Pacific, with comments on the Squalus acanthias subgroup (Squaliformes: Squalidae). Zootaxa 2612: 22 - 40."]}