D ESCRIPTION OF A SPECIES NEW TO SCIENCE

Class Trematoda Rudolphi, 1808 Family Mesometridae Poche, 1926 Genus Wardula Poche, 1926

Wardula bartolii Pérez-del-Olmo, Gibson, Fernández, Sanisidro, Raga & Kostadinova, 2006

Prevalence: 3.3-30.0%.

Meanabundance: 0.03- 2.87.

Localities and dates of collection: NEA (off Ondarroa: 6.vi.2001, 20.vi.2005; Malpica: 12.v.2004, 23.xi.2005, 24.v.2005; Vigo: 18.v.2001, 10.vi.2005, 11.xi.2005, 14.vi.2006, 20.xii.2006, 10.i.2007).

Material studied

Specimens from Boops boops L. (type-host). Rectum. NE Atlantic coasts of Spain: off

Malpica, Galicia (type-locality) (12.v.2004); Vigo, Galicia (18.v.2001); and Ondarroa, Basque Country (6.vi.2001).

Type-material: Holotype BMNH 2005.4.18.1; paratypes BMNH 2005.4.18.2-13,

2005.4.18.14-15.

Etymology: The new species is named for Professor Pierre Bartoli, Centre d’Océanologie de Marseille, in recognition of his major contribution to the morphology, taxonomy, life- history studies and evolution of the Mesometridae.

Description (Figures 4.1., 4.2.)

Based on 16 whole-mounted adult specimens; metrical data in Table 4.1. Body elongate, fusiform, with rounded extremities and maximum width in posterior third of body. Anterior part of body slightly narrower than and delineated from reminder of body by shallow constriction (Figure 4.1.), somewhat leaf-like and concave ventrally (concavity referred to as ‘attachment organ’ by Bartoli & Gibson, 1989). Tegument armed with very fine spines, observed in only few specimens as they are readily lost in fixed material. Numerous

Figure 4.1. Wardula bartolii n. sp. ex Boops boops. A, Holotype, ventral view, anterior end twisted to one side partly obscuring ‘attachment organ’. B, Terminal regions of male (left) and female ducts illustrated

separately (uterus usually obscured by male duct). C. Excretory system. Scale-bar: A,C, 1000 µm.

A

B

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eye-spot pigment granules dispersed in parenchyma of prepharyngeal region. Small pre- oral lobe, clearly seen in lateral view, present in most specimens. Oral sucker ventrally subterminal, subspherical, with buccal ridges furnished with blunt sclerotised denticles which appear to form 1 or 2 transverse arches in ventral view (Figure 4.2A,B). Ventral sucker absent.

Prepharynx very long (30-38% of body length), narrow, with thin wall, difficult to see. Pharynx (‘oesophageal bulb’) subconical, with wide lumen, enlarged to form bulb posteriorly (Figure 4.2C); inner wall sclerotised, transparent, linked to prepharynx through relatively thick projection forming tulip-like structure at junction between pharynx and

prepharynx; this structure consists of 6 pieces whose lateral margins merge at mid-level of

pharynx (Figure 4.2C); outer layers of pharyngeal wall comprised of fine circular muscle fibres covering layer of inner longitudinal muscles with rugged appearance. Two groups of small gland-cells surround anterior and posterior extremities of pharynx (Figure 4.2C). Oesophagus absent. Intestinal caeca 2, relatively narrow but swollen posteriorly in most specimens, end blindly close to anterior margin of anterior testis; anteriorly oriented diverticula absent.

Testes 2, round to transversely-oval, tandem to somewhat oblique, contiguous in posterior quarter of body. Cirrus-sac absent. Long, tubular, convoluted seminal vesicle free in parenchyma, difficult to distinguish, extends from about level of intestinal bifurcation to about anterior third of attachment organ. Pars prostatica indistinct; prostatic sac

(terminology of Bartoli & Gibson, 1989) absent. Ejaculatory duct difficult to distinguish.

Figure 4.2.Wardula bartolii n. sp. ex Boops boops. A, Oral sucker, ventral view. B, Oral sucker, lateral view.

C, Pharynx. Scale-bars: A,B, 200 µm; C, 100 µm.

Genital pore mid-ventral, at level of posterior margin of oral sucker.

Ovary entire, transversely elongate-oval, contiguous with posterior testis or

separated from it by loop of uterus. Mehlis’ gland similar in size to ovary,contiguous with

and dorsal to postero-dorsal to ovary. Uterine seminal receptacle present just anterior to testes. Uterus forms small loop ventral or slightly posterior to ovary and fills inter-caecal region of body between level of anterior testis and pharynx. Metraterm not observed. Vitellarium in 2 lateral fields of relatively small number (see Table 4.1.) of large follicles; fields mostly ventral to caeca and extend between anterior testis and some distance posterior to pharynx (Figure 4.1A). Eggs numerous, operculate, large and rather elongate.

Excretory system reticular (Figure 4.1B). Excretory pore wide, dorso-subterminal.

Remarks

The material described above belongs to the Mesometridae Poche, 1926 because of the absence of a ventral sucker and cirrus-sac, the presence of an accessory attachment organ and the reticulate excretory system (see Bartoli & Gibson, 1989). It shows affinity to the Wardulinae Paggi & Orecchia, 1964 with respect to the structure and distribution of vitellarium and the position of the testes (see Paggi & Orecchia, 1964; Bartoli & Gibson, 1989).

The worms described here exhibit similarities with both known species of Wardula,

i.e. W. capitellata (Rudolphi, 1819) and W. sarguicola Bartoli & Gibson, 1989, but in

different combinations of features. They resemble W. sarguicola in body dimensions and

the slight extension of the uterus posterior to the ovary. However, the body of W. bartolii

appears more robust, with a much wider attachment organ which represents a larger proportion of body length; and the oral sucker and pharynx are larger, the latter also being situated more posteriorly. Furthermore, the gonads of the specimens studied are distinctly transversely elongate (versus subspherical) and located more posteriorly, the vitelline fields

overlap the caeca ventrally (versus intercaecal in W. sarguicola), a prostatic sac is absent,

the genital pore is located at the level of the posterior margin of the oral sucker (versus well

posterior to this level) and the eggs are distinctly larger (mean 84 × 40 versus 71 × 28 µm;

see Table 1 for metrical data).

W. bartolii appears more closely related to W. capitellata, especially in the presence of buccal ridges with sclerotised denticles inside the oral sucker, the posterior location of the testes and ovary which are also contiguous, the distribution of the vitelline follicles and the location of the genital pore at the level of oral sucker. The new species can be

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distinguished from this form, which has only been recorded from Sarpa salpa in the

Mediterranean, in its distinctly smaller body (well outside the range for W. capitellata),

resulting in the smaller dimensions (both ranges and means) for most features (e.g. lengths

of prepharynx and both pre- and post-pharyngeal body-regions, size of gonads, etc.; see

Table 4.1.). The attachment organ of W. bartolii is shorter and wider in relation to body

length, and is not as muscular as that described for W. capitellata (see Bartoli, 1987a).

Furthermore, the caeca lack anterior diverticula, and the more anteriorly located pharynx exhibits a peculiar sclerotised structure of the inner lining.

The peculiar inner structure of the oral sucker, i.e. the multidenticulate ridges which

appear common in mesometrids (but see Bartoli & Gibson, 1989), has been interpreted by

Bartoli (1987a) as a formation adapted to the intestinal microhabitat of the parasites (i.e.

acting as a microfilter for an intestinal chyme dominated by algal fibres in the herbivorous

Sarpa salpa). It is possible that the tulip-like sclerotised oesophageal structure we observed in W. bartolii is also related to preventing the entrance of plant material into the intestinal caeca.