How to achieve internal fertilization without a vagina: the study case of the genus Archilina Ax, 1959 (Platyhelminthes, Proseriata) from Canary Islands

  • Fabio ScarpaEmail author
  • Daria Sanna
  • Piero Cossu
  • Tiziana Lai
  • Marco Casu
  • Marco Curini-Galletti
Part of the following topical collections:
  1. Interstitial and Cave Diversity in Atlantic Oceanic Islands


Five new species of Monocelididae (Platyhelminthes, Proseriata) are described from Eastern Atlantic. Three new Archilina species came from the Canary Islands. Two of them have the cirrus provided with a stylet, cylindrical in Archilina regina sp. nov. and spike-like in Archilina imperatrix sp. nov. Both species lack a vaginal pore: ventrally to the bursa, an area of vacuolar parenchyma is present. Archilina coronata sp. nov. lacks a stylet and has a vaginal pore. The three species are sister taxa to Duploperaclistus circocirrus and Duplominona miranda sp. nov., from Brittany (France), characterized by an extremely long, tubular stylet, about 150 μm in length. A further Archilina is described from Cabo Verde Islands, Archilina regisfilia sp. nov., with a funnel-shaped cirrus and without a vaginal pore. The finding in the Canary Islands of closely related species, occurring abundantly in the same habitats and differing for presence/absence of stylet and vaginal pore, suggests a role of the stylet in allowing internal fertilization in species without external vagina. The phylogeny presented, based on rDNA 18S and 28S genes, does not reflect present systematics of the Monocelididae, and the monophyly of most genera is not supported.


Meiofauna Phylogeny Taxonomy Specie delimitation Hypodermic impregnation 



We thank Prof. Dr. Katrine Worsaae and Dr. Alejandro Martinez for organizing the workshop in Lanzarote in autumn 2011. We acknowledge for partial funding support ASSEMBLE grant agreement no. 227799 given to FS, VD for sampling in Roscoff, and to MCG for sampling in Faro. We thank the Director of the “Parco Nazionale dell’Isola di Asinara” for sampling permission. Dr. Valentina Delogu is thanked for her skillful assistance in preparing the histological sections. The title of the section “How the worm got its stylet” is coined after the seminal paper by Jondelius et al. 2011: “How the worm got its pharynx: phylogeny, classification and Bayesian assessment of character evolution in Acoela.”


This study was funded by X (grant number X).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed by the authors.

Sampling and field studies

All necessary permits for sampling and observational field studies have been obtained by the authors from the competent authorities and are mentioned in the acknowledgements, if applicable.

Supplementary material

12526_2018_890_MOESM1_ESM.doc (288 kb)
ESM 1 (DOC 288 kb)
12526_2018_890_MOESM2_ESM.doc (59 kb)
ESM 2 (DOC 59 kb)


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Copyright information

© Senckenberg Gesellschaft für Naturforschung and Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Dipartimento di Medicina VeterinariaUniversità degli Studi di SassariSassariItaly
  2. 2.Dipartimento di Scienze Biomediche, Università degli Studi di SassariSassariItaly

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