Antarctic Ascidians (Tunicata) of the French-Australian survey CEAMARC in Terre Adélie

Abstract

A large collection of ascidians was made during the CEAMARC Aurora Australis V3 cruise off Terre Adélie and George V Land a region rarely investigated before at these depths. Sampling was performed by beam trawls and a dredge between 138°– 146° latitude East and from 150 to 1700 m depth, on the Antarctic shelf and slope. Three of the 33 ascidian species identified are new and belong to the Stolidobranchia. Half of the species have an exclusive Antarctic distribution, others also occur in Sub-Antarctic areas, but none are common with the southern temperate fauna. The CEAMARC collection does not contain the whole range of already known species from this region. Moreover, brittle and very small specimens were not collected. COI sequences were obtained for 37 specimens, including two of the new species.

Not as clear as expected: what genetic data tell about Southern Hemisphere corellids (Ascidiacea: Phlebobranchia)

“…This interspecific distance is also higher than the intraspecific distances found for C. eumyota (0.9%) and C. antarctica (4.2%), supporting the differentiation of both species using COI sequences as molecular markers. Despite the few DNA sequences available for Corella (highlighted by Monniot et al 2011), this study shows lower variable intraspecific distances than previous reports (up to 20.77%) for Antarctic and Sub-Antarctic ascidians Monniot et al 2011). Our haplotype network and phylogenetic trees are the first to collate all available data, both molecular and morphological, and agree with the preliminary findings of Monniot et al (2011) showing a close relationship between C. suhmi and C. antarctica (mentioned as C. eumyota in that study).…”

“…Sequences obtained from GenBank and BOLD System databases were included in the analysis for comparison and as outgroups (Stach and Turbeville 2002;Kurabayashi et al 2003;Monniot et al 2011;Pyo et al 2012;López-Legentil et al 2015;Turon et al 2016). Once aligned using the BioEdit program 7.0.5.3 (Hall 1999), sequences were collapsed into haplotypes; the number of polymorphic sites and haplotypes were calculated using the program DNAsp 6 (Rozas et al 2017).…”

“…Subsequently, Alurralde et al (2013) re-established the Antarctic species, Corella antarctica Sluiter, 1905, based on morphological differences with its congener from Sub-Antarctic areas, while Monniot (2013) described a new species (Corella brewinae Monniot F., 2013) from New Zealand. Furthermore, Monniot et al (2011) reported over 10% divergence among cytochrome oxidase subunit I (COI) mitochondrial gene sequences of C. antarctica (referred to as C. eumyota in that paper) and C. eumyota, but 93.75% similarity with Corynascidia suhmi Herdman, 1882, another corellid species. The morphology of C. eumyota and C. antarctica are clearly different (Alurralde et al 2013;Monniot 2013), which raises the question of whether the morphological variation is genetically supported, and also what the genetic data may tell us in regard to Southern Hemisphere corellids.…”

“…Species that belong to the family Corellidae (Ascidiacea: Phlebobranchia), and particularly those of the genus Corella, not only exhibit a wide range of morphological variability (Herdman 1910;Hartmeyer 1924;Ärnbäck-Christie-Linde 1938;Van Name 1945;Brewin 1946;Kott 1969;Lambert et al 1981Lambert et al , 1995Monniot 1994Monniot , 2013Monniot and Monniot 1994;Sanamyan 2002, 2005;Lambert 2004;Varela et al 2007;Alurralde et al 2013), but also present a similar range of genetic discrepancies (Dupont et al 2007;Monniot et al 2011). The most recent debate involved Corella eumyota Traustedt, 1882, a Corella species from southern South America and Antarctica (Alurralde et al 2013;Monniot 2013), successfully invasive in the Northern Hemisphere (Lambert 2004;Arenas et al 2006;Minchin 2007;Varela et al 2007;Collin et al 2010;Nagar et al 2010) and with a high invasive potential in similar environments (Locke 2009).…”

Conveniently Pre-Tagged and Pre-Packaged: Extended Molecular Identification and Metagenomics Using Complete Metazoan Mitochondrial Genomes

“…For five groups, datasets with both 18S and mitochondrial sequences available for the same specimens were identified, either through the Barcode of Life Data system (BOLD) project listing (all projects including several 18S rDNA sequences: [29], [30], [31]) or through publications databases ([32], [33]). Pairwise distances for species from the same genus or between genera in the same family were estimated either using the BOLD distance summary tool or the results of the publications.…”