Morphological evidence that the molecularly determined Ciona intestinalis type A and type B are different species: Ciona robusta and Ciona intestinalis

By R. Brunetti, Carmela Gissi, R. Pennati, F. Caicci, F. Gasparini, L. Manni. 2015

241 citations recorded by the source corpus.

Ciona intestinalis is considered a widespread and easily recognizable tunicate, the sister group of vertebrates. In recent years, molecular studies suggested that C. intestinalis includes at least two cryptic species, named ‘type A’ and ‘type B’, morphologically indistinguishable. It is dramatic to certify that two different species may be hidden under the name of a species widely used as a model species in biological researches. This raised the problem of identifying diagnostic morphological characters capable of distinguishing these types. We compared the morphology of specimens belonging to the two types and found that only type A specimens possess tunic tubercular prominences, allowing unambiguous discrimination. Remarkably, these structures were already described as distinctive of the Japanese species Ciona robusta, Hoshino and Tokioka, 1967; later synonymized under C. intestinalis (sensu Millar, 1953). In this study, we have confirmed that C. intestinalis type A corresponds to C. robusta. Based on the geographic distribution of C. intestinalis type B, and considering that the original C. intestinalis species was described from North European waters, we determined that C. intestinalis type B corresponds to C. intestinalis as described by Millar in 1953 and possibly to Linnaeus’ Ascidia intestinalis L., 1767 for which we have deposited a neotype (from Roscoff, France) and for which we retain the name Ciona intestinalis (Linnaeus, 1767).

Subfields: Ecology, Global and Planetary Change, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/d69b98eef314ad8c96218c8a60a49711189b49cb

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In Ecology

1. Aibin Zhan
2. H. MacIsaac
3. Elizabeta Briski
4. A. Ricciardi
5. P. Hulme
6. Francesca Gherardi

In Global and Planetary Change

1. Aibin Zhan
2. Dan G. Bock
3. H. MacIsaac
4. Elizabeta Briski
5. Sara Ghabooli

In Ocean Engineering

1. Aibin Zhan
2. Dan G. Bock
3. H. MacIsaac
4. Elizabeta Briski
5. Sara Ghabooli

Citations in the corpus

• Ascidians as models for studying invasion success (2015, background): “While several highly invasive species such as C. intestinalis spA (=Ciona robusta, Brunetti et al. 2015) and spB (=C. intestinalis, Brunetti et al. 1 3 2015) and B. schlosseri spA have disjunct global distributions, other members of these species complexes largely remain restricted to their native…”