Abstract
Rhabdocoels comprise a large group of flatworms that currently consists of two major subgroups: (1) Kalyptorhynchia with an anterior proboscis and (2) Dalytyphloplanida without a proboscis. Most genera of rhabdocoels can easily be classified into one of these two subgroups, except for the three monotypic representatives of the Mariplanellinae. Comparative morphological data and previous molecular phylogenetic analyses have so far been unable to determine the positions of these rarely encountered microturbellarians within the context of rhabdocoels. Here we describe a new species of Mariplanellinae, Mariplanella piscadera sp. nov. from Curaçao (Dutch Caribbean), and present an updated phylogeny inferred from 18S and 28S rDNA sequences, including data from M. piscadera sp. nov., M. frisia, and a selection of rhabdocoels, proseriates and other trepaxonematan flatworms. Our molecular phylogenetic trees reveal that Mariplanella belongs to a distinct higher-level group of rhabdocoels that forms the sister lineage to a clade uniting Kalyptorhynchia and Dalytyphloplanida. Therefore, we update the status of Mariplanellinae to Mariplanellida status novus, containing the family Mariplanellidae status novus, in order to better reflect our current understanding of rhabdocoel phylogeny and the establishment of now three major subgroups.
This is a preview of subscription content, access via your institution.



Availability of data and material
The sequence alignments and molecular phylogenetic trees of this study are available in Mendeley Data, V1, https://doi.org/10.17632/94w8tfp972.1. GenBank accession numbers of the sequences generated for this study are included in Table S2.
References
Artois, T. (2020). Rhabdocoela C. G. Ehrenberg 1831 [T. Artois], converted clade name; Dalytyphloplanida W. R. Willems et al. 2006 [T. Artois], converted clade name; Kalyptorhynchia L. Graff 1905 [T. Artois], converted clade name. In K. de Queiroz, P. D. Cantino, & J. A. Gauthier (Eds.), Phylonyms: A Companion to the PhyloCode (1st ed., pp. 511–518). Boca Raton: CRC Press. https://doi.org/10.1201/9780429446276
Ax, P., & Heller, R. (1970). Neue Neorhabdocoela (Turbellaria) von der Sandstrand der Nordsee-Insel Sylt. Mikrofauna Des Meeresbodens, 2, 55–98.
Curini-Galletti, M., Webster, B. L., Huyse, T., Casu, M., Schockaert, E. R., Artois, T. J., & Littlewood, D. T. J. (2010). New insights on the phylogenetic relationships of the Proseriata (Platyhelminthes), with proposal of a new genus of the family Coelogynoporidae. Zootaxa, 2537(1), 1–18. https://doi.org/10.11646/zootaxa.2537.1.1
Egger, B., Lapraz, F., Tomiczek, B., Müller, S., Dessimoz, C., Girstmair, J., et al. (2015). A transcriptomic-phylogenomic analysis of the evolutionary relationships of flatworms. Current Biology, 25(10), 1347–1353. https://doi.org/10.1016/j.cub.2015.03.034
Ehlers, U. (1974). Interstitielle Typhloplanoida (Turbellaria) aus dem Litoral der Nordseeinsel Sylt. Mikrofauna Des Meeresbodens, 49, 427–526.
Gobert, S., Diez, Y. L., Monnens, M., Reygel, P., Van Steenkiste, N. W. L., Leander, B. S., & Artois, T. (2021). A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species. Zootaxa, 4970(3), 453–494. https://doi.org/10.11646/zootaxa.4970.3.2
Huson, D. H., & Bryant, D. (2006). Application of phylogenetic networks in evolutionary studies. Molecular Biology and Evolution, 23(2), 254–267. https://doi.org/10.1093/molbev/msj030
Katoh, K., & Toh, H. (2008). Recent developments in the MAFFT multiple sequence alignment program. Briefings in Bioinformatics, 9(4), 286–298. https://doi.org/10.1093/bib/bbn013
Kearse, M., Moir, R., Wilson, A., Stones-Havas, S., Cheung, M., Sturrock, S., et al. (2012). Geneious Basic: An integrated and extendable desktop software platform for the organization and analysis of sequence data. Bioinformatics, 28(12), 1647–1649. https://doi.org/10.1093/bioinformatics/bts199
Lanfear, R., Frandsen, P. B., Wright, A. M., Senfeld, T., & Calcott, B. (2017). Partitionfinder 2: New methods for selecting partitioned models of evolution for molecular and morphological phylogenetic analyses. Molecular Biology and Evolution, 34(3), 772–773. https://doi.org/10.1093/molbev/msw260
Laumer, C. E., Hejnol, A., & Giribet, G. (2015). Nuclear genomic signals of the “microturbellarian” roots of platyhelminth evolutionary innovation. eLife, 4. https://doi.org/10.7554/eLife.05503
Nguyen, L.-T., Schmidt, H. A., von Haeseler, A., & Minh, B. Q. (2015). IQ-TREE: A fast and effective stochastic algorithm for estimating maximum likelihood phylogenies. Molecular Biology and Evolution, 32(1), 268–274. https://doi.org/10.1093/molbev/msu300
Raikova, O. I., Kotikova, E. A., Korgina, E. M., & Drobysheva, I. M. (2019). Time to re-assess pharynx evolution in flatworms. Homology of pharynx rosulatus in rhabdocoel flatworms Dalytyphloplanida and Kalyptorhynchia. Invertebrate Zoology, 16(1), 57–70. https://doi.org/10.15298/invertzool.16.1.07
Ronquist, F., & Huelsenbeck, J. P. (2003). MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics, 19(12), 1572–1574. https://doi.org/10.1093/bioinformatics/btg180
Schockaert, E. R. (1996). Turbellarians. In G. Hall (Ed.), Methods for the examination of organismal diversity in soils and sediments (pp. 211–225). CAB International.
Smith, J. P. S., III., Litvaitis, M. K., Gobert, S., Uyeno, T., & Artois, T. (2015). Evolution and Functional Morphology of the Proboscis in Kalyptorhynchia (Platyhelminthes). Integrative and Comparative Biology, 55(2), 205–216. https://doi.org/10.1093/icb/icv056
Stamatakis, A. (2014). RAxML version 8: A tool for phylogenetic analysis and post-analysis of large phylogenies. Bioinformatics, 30(9), 1312–1313. https://doi.org/10.1093/bioinformatics/btu033
Steenwyk, J. L., Buida, T. J., Li, Y., Shen, X. X., & Rokas, A. (2020). ClipKIT: A multiple sequence alignment trimming software for accurate phylogenomic inference. PLoS Biology, 18(12), e3001007. https://doi.org/10.1371/journal.pbio.3001007
Tessens, B., Janssen, T., & Artois, T. (2014). Molecular phylogeny of Kalyptorhynchia (Rhabdocoela, Platyhelminthes) inferred from ribosomal sequence data. Zoologica Scripta, 43(5), 519–530. https://doi.org/10.1111/zsc.12066
Van Steenkiste, N., Tessens, B., Willems, W., Backeljau, T., Jondelius, U., & Artois, T. (2013). A comprehensive molecular phylogeny of Dalytyphloplanida (Platyhelminthes: Rhabdocoela) reveals multiple escapes from the marine environment and origins of symbiotic relationships. PLoS One, 8(3), e59917. https://doi.org/10.1371/journal.pone.0059917
Van Steenkiste, N. W., & Leander, B. S. (2018). Species diversity of eukalyptorhynch flatworms (Platyhelminthes, Rhabdocoela) from the coastal margin of British Columbia: Polycystididae, Koinocystididae and Gnathorhynchidae. Marine Biology Research, 14(9–10), 899–923. https://doi.org/10.1080/17451000.2019.1575514
Willems, W., Artois, T., Vermin, W., Backeljau, T., & Schockaert, E. (2005). “Typhloplanoida” (Platyhelminthes: Rhabdocoela) from the Indian Ocean, with the description of six new taxa. Journal of Natural History, 39(19), 1561–1582. https://doi.org/10.1080/00222930400014239
Willems, W. R., Wallberg, A., Jondelius, U., Littlewood, D. T. J., Backeljau, T., Schockaert, E. R., & Artois, T. J. (2006). Filling a gap in the phylogeny of flatworms: Relationships within the Rhabdocoela (Platyhelminthes), inferred from 18S ribosomal DNA sequences. Zoologica Scripta, 35(1), 1–17. https://doi.org/10.1111/j.1463-6409.2005.00216.x
Acknowledgements
We are grateful to the Caribbean Research and Management of Biodiversity Institute (CARMABI) and their helpful staff for supporting the sampling campaign in Curaçao. We also like to thank two anonymous reviewers for their valuable suggestions to improve this work.
Funding
This work was funded by the Canadian Institute for Advanced Research (CIFAR), the Tula Foundation’s Hakai Institute and the National Sciences and Engineering Research Council of Canada (NSERC 2019–03986).
Author information
Authors and Affiliations
Contributions
NWLVS and BSL took part in conceptualization; NWLVS involved in methodology; NWLVS took part in formal analysis and investigation; NWLVS and BSL involved in writing—original draft preparation; NWLVS and BSL took part in writing—review and editing; BSL involved in funding acquisition; BSL took part in resources; BSL took part in supervision.
Corresponding author
Ethics declarations
Ethical approval
No approval of research ethics committees was required because the work was conducted with unregulated invertebrate species.
Consent for publication
All authors consent to the submission and publication of this article upon acceptance.
Conflict of interest
The authors have no conflict of interest to declare that are relevant to the content of this article.
Additional information
Publisher's note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Van Steenkiste, N.W.L., Leander, B.S. The molecular phylogenetic position of Mariplanella piscadera sp. nov. reveals a new major group of rhabdocoel flatworms: Mariplanellida status novus (Platyhelminthes: Rhabdocoela). Org Divers Evol 22, 577–584 (2022). https://doi.org/10.1007/s13127-022-00542-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13127-022-00542-2
Keyword
- Microturbellaria
- Mariplanellinae
- Meiofauna
- Phylogeny
- Curaçao
- Caribbean