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Review
. 2011;6(6):e20657.
doi: 10.1371/journal.pone.0020657. Epub 2011 Jun 20.

Global diversity of Ascidiacea

Noa Shenkar  1 , Billie J Swalla
Affiliations
Review

Global diversity of Ascidiacea

Noa Shenkar et al. PLoS One. 2011.

Abstract

The class Ascidiacea presents fundamental opportunities for research in the fields of development, evolution, ecology, natural products and more. This review provides a comprehensive overview of the current knowledge regarding the global biodiversity of the class Ascidiacea, focusing in their taxonomy, main regions of biodiversity, and distribution patterns. Based on analysis of the literature and the species registered in the online World Register of Marine Species, we assembled a list of 2815 described species. The highest number of species and families is found in the order Aplousobranchia. Didemnidae and Styelidae families have the highest number of species with more than 500 within each group. Sixty percent of described species are colonial. Species richness is highest in tropical regions, where colonial species predominate. In higher latitudes solitary species gradually contribute more to the total species richness. We emphasize the strong association between species richness and sampling efforts, and discuss the risks of invasive species. Our inventory is certainly incomplete as the ascidian fauna in many areas around the world is relatively poorly known, and many new species continue to be discovered and described each year.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Ascidian branchial sac structure, a distinguishing taxonomic character.
a) A simple branchial arrangement in an aplousobranch (Didemnum sp.). Arrows pointing out the straight stigmata rows. Photo: A. Shoob. Scale bar 1 mm; b) phlebobranch (Ascidia sp.) with longitudinal blood vessels; c) stolidobranch (Herdmania momus) with branchial folds. Photos: N Shenkar. Scale bar 1 mm and 4 mm respectively.
Figure 2
Figure 2. Systematic division of ascidian species.
a) Number and percentage of species per order; b) number of species by family within each order.
Figure 3
Figure 3. Discovery rate and author contribution.
a) Cumulative number of valid ascidian species described between 1750–2010; b) Percentage and number of species described per taxonomic authority. Note: only taxonomic authorities with more than 100 species are mentioned by name.
Figure 4
Figure 4. Ascidian global distribution (abyssal species not included).
See this image and copyright information in PMC

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