Phylogenetic relationships of a new schizorhynch genus refute the monophyly of Schizochilus Boaden, 1963 (Platyhelminthes, Rhabdocoela)
Diez, Y.L.; Reyes, J.; Hermans, S.; Sweat, L.H.; Monnens, M.; Artois, T. (2026). Phylogenetic relationships of a new schizorhynch genus refute the monophyly of Schizochilus Boaden, 1963 (Platyhelminthes, Rhabdocoela). Mar. Biodiv. 56(2): 26. https://dx.doi.org/10.1007/s12526-026-01627-3
In: Marine Biodiversity. Springer: Heidelberg; Berlin. ISSN 1867-1616; e-ISSN 1867-1624, more
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| Keywords |
Kalyptorhynchia [WoRMS]; Schizochilus Boaden, 1963 [WoRMS]; Schizorhynchidae Graff, 1905 [WoRMS]
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| Author keywords |
Microturbellaria · Molecular phylogeny · Proboscis |
| Authors | | Top |
- Diez, Y.L., more
- Reyes, J.
- Hermans, S.
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- Sweat, L.H.
- Monnens, M., more
- Artois, T., more
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| Abstract |
Three new species of Pseudoschizochilus gen. nov. (Platyhelminthes, Rhabdocoela, Schizorhynchia) from Cuba and the southeastern coast of the United States are described based on morphology and molecular phylogenetic analyses (18S and 28S rDNA). Species of the new genus are characterised by a conjuncta-duplex type male copulatory organ, which terminates in a sclerotised cap and comprises a prostate vesicle, a cirrus, and a stylet. The female system features an elaborate bursa which proximally opens to the digestive parenchyma through an internal pore. Morphologically, representatives of Pseudoschizochilus gen. nov. closely resemble species of Schizochilus Boaden, 1963. However, molecular phylogenetic analyses reveal that species of Pseudoschizochilus gen. nov. and Schizochilus form distinct clades, with the former clustering with Schizorhynchoides Meixner, 1928, and the latter with other schizorhynchids (excluding Carcharodorhynchus Meixner, 1938), karkinorhynchids, and diascorhynchids. Based on these analyses, Schizochilus atlanticus Diez, Reygel & Artois, 2019 and S. lanzarotensis Gobert, Reygel & Artois, 2019 are transferred to Pseudoschizochilus gen. nov., clustering with P. lyratus sp. nov. Given the morphological similarities of some other species of Schizochilus with P. atlanticus comb. nov., it is likely they also belong to Pseudoschizochilus gen. nov. However, this hypothesis must be corroborated by future phylogenetic analyses. The three new species of Pseudoschizochilus gen. nov. are primarily differentiated from each other by bursa morphology and stylet length: ~ 757 μm in P. lyratus sp. nov., ~ 337 μm in P. orientalis sp. nov., and 65 μm in P. occidentalis sp. nov. |
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