Plectanocotyle Diesing, 1850

Cappelletti, Alice & Bouguerche, Chahinez, 2024, “ Something old, something new, something borrowed, and the oioxeny is true ”: description of Plectanocotyle jeanloujustinei n. sp. (Polyopisthocotylea, Plectanocotylidae) from the MNHN Helminthology collection with novel molecular and morphological data for P. gurnardi (Van Beneden & Hesse, 1863) (sensu stricto) from Sweden, International Journal for Parasitology: Parasites and Wildlife 23, pp. 100914-100914 : 100914-

Genus Plectanocotyle Diesing, 1850 .

divergence bewteen P. gurnardi sensu stricto from Sweden, North Sea and P. gurnardi from the same host from the North Sea as well, off the U.K., and those from the northern coast of the Western Mediterranean off France was 0%.

The divergence between P. gurnardi sensu stricto from E. gurnardus from the North Sea from Sweden and Plectanocotyle sp. from C. lastovizae from the northern coast of the Western Mediterranean off France was 3–4 %. Similarly, the divergence between Plectanocotyle sp. from C. lastovizae from the Western Mediterranean off France and P. gurnardi from E. gurnardus from the same locality was 3 %.

3.2.1. Plectanocotyle gurnardi ( Van Beneden and Hesse, 1863) sensu stricto ( Figs. 6–8 )

Synonyms: Plectanocotyle caudata Lebour, 1908 ; Llewellyn, 1941); present study.

Type-host: Eutrigla gurnardus ( Perciformes : Triglidae ), the grey gurnard ( Van Beneden and Hesse, 1863).

Other hosts: Chelidonichthys cuculus (referred to as Trigla cuculus ) ( Llewellyn, 1941, 1956; Whittington and Kearn, 1989).

Type-locality: off Belgium, Northeast Atlantic ( Van Beneden and Hesse, 1863).

Other localities: Northeast Atlantic: off Plymouth ( Llewellyn, 1956; Whittington and Kearn, 1989); off Ireland ( Llewellyn, 1941); Skagerrak and Kattegat, Sweden (present study).

Site on host: Gills.

Specimens deposited:

Specimens with molecular information: Body (lacking only a small lateral part) mounted on a slide, excised lateral part used for molecular analysis: specimens from Eutrigla gurnardus off the coast of Sweden, Northeast Atlantic; SMNH 216644, GenBank PP297654, PP314023; SMNH 216645, GenBank PP297655, PP326836; SMNH 216646, GenBank PP297658, PP314021; SMNH 222174, GenBank PP297659; SMNH 222175, GenBank PP297660; SMNH 222176, GenBank PP297661; SMNH 222177, GenBank PP297663; SMNH 222178, GenBank PP297664; SMNH 222179, GenBank PP297665.

Specimens examined for the morphological study, whole mounts: Plectanocotyle gurnardi from Eutrigla gurnardus from Sweden, Northeast Atlantic, from Tj¨arn¨o (SMNH 216644–216646), and from Kattegat (SMNH 216572, SMNH 216575–79, SMNH 216584–98, SMNH 216603, SMNH 216615, SMNH 216623, SMNH 216635).

Material examined for comparison: P. gurnardi from E. gurnardus , from Kristineberg, Sweden, Northeast Atlantic; from the collection of T. Odhner (SMNH 222180) deposited in the Invertebrates collection in the

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SMNH.

3.2.1.1. Description. Measurements in Table 5. Measurements of hologenophores provided separately in Table 6. Body elongated, rounded anteriorly ( Fig. 6 A ); with maximum width at level of ovary. Haptor almost triangular, symmetrical, weakly delimited from body proper, bearing three pairs of clamps. Clamps pedunculated ( Fig. 6 B ), arranged in two short rows, slightly dissimilar in size anteroposteriorly.

Clamps consisting of two opposable jaws, anterior jaw ( Fig. 7 A ) and posterior jaw ( Fig. 7 B ). Ventral arm of median spring a T-shaped, long, distal part of a with large, short branches of equal size, each limb abutting on lateral sclerites. Dorsal arm of median spring a visibly shorter than its ventral arm, distally broad, with few apertures arranged in longitudinal parallel rows. Ventral arm of ventral jaw consisting of two lateral sclerites b2, dorsal arm b3 shorter and curved inwards; b3 not reaching dorsal arm of median spring ( Fig. 3B ). Dorsal jaw sclerites c longer than ventral, formed by two superposed sclerites; c reaching midline on distal side. Muscles connecting a and b2 present on proximal side ( Fig. 7 C ).

Anchor-bearing terminal lappet present ( Fig. 6 C ), linguiform, consisting of a slender long outgrowth. Terminal lappet bearing three pairs of anchors: two pairs of hamuli and one pair of uncinuli. Lateral hamuli occasionally twice as long as median hamuli. Median hamulus smaller. Uncinuli small, located between hamuli.

Mouth subterminal, elongated transversally. Oral suckers paired, anteriorly placed, subcircular. Pharynx muscular, globular, median. Oesophagus not observed. Intestinal bifurcation anterior to MCO. Caeca with numerous medial and lateral secondary branches, extending into haptor, up to 2/3 total length of haptor. Caeca not confluent posteriorly.

Testes post-ovarian, occupying intercaecal space extending from ovary to haptor; 17–27 in number. Vas deferens medio-dorsal, wide, sinuous, extending anteriorly along mid-longitudinal body axis. Anteriorly, vas deferens expanded into a weekly distinct seminal vesicle in the anterior region.

In its anterior region, vas deferens ending in a narrow duct opening posteriorly in genital atrium. Genital pore near intestinal bifurcation. Cirrus consisting of a sheaf of long spines. Peripheral spines tightly packed in sections. Most inner spines (median) shorter. Median spines delineating a thin canal, receiving the vas deferens.

Male accessory glands paired, with corresponding reservoirs, located at level of cirrus on each side of the body ( Fig. 6 C ). Male accessory glands with numerous prostatic glands. Secretions of prostatic glands accumulating in small reservoirs. Each reservoir continued rearward by a short duct. Ducts emerging from reservoirs joined medially, forming a prostatic canal. Prostatic canal entering the bundle of spines and uniting with vas deferens.

Ovary complex begins at level of anteriormost testes ( Fig. 8 ). Proximal section irregularly shaped. Ovary continues anteriorly in midline, reflexes again toward anterior extremity, forming large anterior curve before ending in oviduct. Oviduct joined by vitelline reservoir in midline. Genito-intestinal canal (visible only in certain specimens) extending from oviduct ventrally across proximal end of ovary and entering right intestinal caecum. Ootype ¨spindle-shaped, Mehlis’ glands hardly discernible, visible in few specimens. Uterus in midline. Vitellarium co-extensive with intestinal caeca reaching up to haptor region and extending into haptor. Transverse vitelline ducts paired, united

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anteriorly and posteriorly; posterior junction of transverse vitelline ducts Y-shaped, conspicuous in most specimens, at level of ovary and ventral to it. Egg fusiform ( Fig. 6 D ), with a single polar filament. Egg filament short, often coiled.

Figures

Fig. 6. Plectanocotyle gurnardi (Van Beneden and Hesse, 1863) sensu stricto ex Eutrigla gurnardus from the North Sea, Sweden. A, Body, ventral view (SMNH 216639). B, Clamp, ventral view (SMNH 216593). C, Anterior end showing male copulatory organ, ventral view (SMNH 216586). D, Egg, (SMNH 216594).

Fig. 7. Plectanocotyle gurnardi (Van Beneden and Hesse, 1863) sensu stricto ex Eutrigla gurnardus from the North Sea, Sweden, disposition of clamps sclerites. A, Dorsal jaw. B, Ventral jaw. C, Clamp, ventral view (SMNH 216593). 3.2. Morphology

Fig. 8. Plectanocotyle gurnardi (Van Beneden and Hesse, 1863) sensu stricto ex Eutrigla gurnardus from the North Sea, Sweden, Detail of the reproductive organs in the region of ovary, ventral view (SMNH 216584).

Fig. 3. Plectanocotyle jeanloujustinei n. sp. ex Chelidonichthys lastoviza from the western Mediterranean (Algeria), hologenophores. A-E, Body lacking only the haptor. F. Body lacking a lateral part posterior part. G-H, anterior end of the body including the male copulatory organ. The missing parts were excised and used for DNA extraction. A, (HEL1729). B, (HEL1730). C, (HEL1732). D, (HEL1733). E, (HEL1734). F, (HEL1731). G, (HEL1727). H, (HEL17287).