Izmira lusitanica, Pérez-García & Gouveia & Calado & Noreña & Cervera, 2024

Pérez-García, Patricia, Gouveia, Filipa, Calado, Gonçalo, Noreña, Carolina & Cervera, Juan Lucas, 2024, Acotylea (Platyhelminthes, Polycladida) from the southern and western Iberian Peninsula, with the description of five new species, Zoosystematics and Evolution 100 (4), pp. 1487-1513 : 1487-1513

Izmira lusitanica sp. nov.

Fig. 12

Holotype.

• MNHNC MB 16-000124 , Station 4 , 8 December 2018, 21 mm fixed, sagittal sectioned into 16 slides.

Additional material.

• MNHNC MB 16-000134 , Station 4 , 9 March 2019, 13 mm, juvenile .

Diagnosis.

Pleioplanidae with transparent body; tentacles absent; with cerebral eyes, gonopores separated; small and bean-shaped seminal vesicle; prostatic vesicle oval; elongated penis papilla; female apparatus with a vagina bulbosa.

Description.

Body shape elongated and delicate, widened anteriorly and tapered distally. The mature specimen is approximately 21 mm long when alive, while the juvenile specimen is approximately 13 mm in length.

Dorsal surface transparent, brownish-coloured intestinal branches easily observable (Fig. 12 A ), central longitudinal area lacks pigmentation. Ventral side translucent. Tentacles absent. Paired clusters of tentacular and cerebral eyes present, with approximately 28 tentacular eyes and 42 cerebral eyes in each cluster (Fig. 12 B ). Pharynx ruffled and centrally located between the second and third fourths of the body, oral pore at the beginning of the last third of the pharynx. Gonopores separated and located between the third and the last fourth of the body.

Reproductive system.

Male reproductive organs composed of a true seminal vesicle, an interpolated oval-shaped prostatic vesicle, and a long penis rod. Vas deferens thick, forming spermiducal bulbs that run ventrally and proximally and enter separately into the seminal vesicle. Seminal vesicle bean-shaped and small (0.25 mm) located proximal to the prostatic vesicle (Fig. 12 D ). Prostatic vesicle well developed (0.5 mm), with chambered epithelial linings (Fig. 12 C, D ). Ejaculatory duct runs from the proximal to the distal end of the prostatic vesicle. Penis papilla muscular, broad (0.35 mm long; 0.09 mm wide), and conical (Fig. 12 C, D ). Diameter of the penis papilla decreases from proximal to distal.

Female copulatory apparatus with a wide external vagina (0.21 mm) with several folds and a bulbous vagina (Fig. 12 C, D ). Internal vagina long and narrow, without Lang’s vesicle. Several cement glands surround the internal vagina.

Type locality.

Area Marinha Protegida das Avencas, Parede, Cascais, Portugal.

Etymology.

The specific name refers to Lusitania, the original Roman name of the region from Portugal where the holotype was collected.

Remarks.

The genus Izmira was established by Bulnes in 2010 based on specimens from the Aegean Sea. The representatives of this genus are characterised by an oval or elongated body, absence of tentacles, presence of tentacular eyes, absence of cerebral, frontal, or marginal eyes, separated gonopores, a true seminal vesicle, an interpolated “ atomata ” type of prostatic vesicle, a penis rod, and a female reproductive system with a vagina bulbosa and without Lang’s vesicle. The species described in the present work shows these features except for the presence of cerebral eyes, which are observable in I. lusitanica sp. nov.

The genus Izmira comprises only two previously known species: I. cinari Bulnes 2010 and I. turkeyi Bulnes 2010 . I. lusitanica sp. nov. shares several characteristics with I. turkeyi , including separated gonopores, the presence of spermiducal bulbs, a similar length of the penis rod, and a similar structure of the vagina bulbosa. However, they exhibit notable differences; for instance, the body shape of I. turkeyi is oval, whereas that of I. lusitanica sp. nov. is elongated; the colouration of I. turkeyi tends to be dark, whereas that of I. lusitanica sp. nov. is distinctly transparent; and I. turkeyi possesses tentacle knobs, a feature absent in the new species. Furthermore, the presence of cerebral eyes distinguishes the two species; I. turkeyi lacks them, whereas I. lusitanica sp. nov. has them. Notably, I. turkeyi has a seminal vesicle longer than the prostatic vesicle, whereas I. lusitanica sp. nov. has a bean-shaped seminal vesicle, smaller than the prostatic vesicle. Moreover, the prostatic vesicle is small and rounded in I. turkeyi but large and oval-shaped in the new species. The shape of the penis papilla also differs significantly: in I. turkeyi , the penis papilla forms a rounded pouch distally, whereas in I. lusitanica sp. nov., it narrows and has a conical shape.

On the other hand, significant differences exist between I. cinari and I. lusitanica . sp. nov .. I. cinari is light brown and darker medially, while I. lusitanica sp. nov. is transparent. Cerebral eyes are absent in I. cinari but present in I. lusitanica sp. nov.. The seminal vesicle in I. cinari is longer than the prostatic vesicle, whereas in I. lusitanica sp. nov., it is bean-shaped and small. Additionally, the prostatic vesicle is different: rounded in I. cinari and large and oval in I. lusitanica sp. nov.. The penis papilla of the Turkish species is longer than that of the new species.

These observed differences between the valid Izmira species and the unique combination of characteristics observed in I. lusitanica sp. nov. led us to consider the specimens from Avencas as a new species. This is the first record of the genus Izmira outside the Mediterranean.

Figures

Figure 12. Izmira lusitanica sp. nov. (holotype, MNHNC MB 16-000124). Histological sections are postero-anteriorly oriented: A. Dorsal view of a living specimen; B. Detail of the tentacular and cerebral eyes (holotype); C. Histological section of the reproductive system (holotype); D. Sagittal reconstruction of the reproductive system (holotype). Abbreviations: cg, cemental glands; ed, ejaculatory duct; eg, extravesicular glands; el, epithelial lining; ev, external vagina; fp, female pore; i, intestine; iv, internal vagina; mw, muscular wall; ph, pharynx; pr, penis rod; pv, prostatic vesicle; sv, seminal vesicle.