A revision of the genus Thouarella Gray, 1870 (Octocorallia: Primnoidae), including an illustrated dichotomous key, a new species description, and comments on Plumarella Gray, 1870 and Dasystenella, Versluys, 1906

Abstract

A comprehensive revision of the genus Thouarella is presented. Thirty-five holotypes of the 38 nominal Thouarella species, two varieties, and one form were examined. The number of original Thouarella species has been reduced to 25, mostly through synonymy or new genus combinations. In the process several new species have also been identified, one of which is described here as Thouarella parachilensis nov. sp. The genus is split into two groups based on polyp arrangement: Group 1 with isolated polyps and Group 2 with polyps in pairs or whorls. An illustrated dichotomous key and detailed character table of the 25 Thouarella species are presented alongside an up-to-date account of all species described in the 19th and 20th centuries and summaries of the few described from 2000 onwards. We propose that Thouarella longispinosa is synonymous with Dasystenella acanthina, T. versluysi with T. brucei, and, T. tenuisquamis, T. flabellata, and T. carinata are synonymous with T. laxa. Lastly, we propose that T. bayeri and T. undulata be placed in Plumarella and support recent suggestions that T. alternata, T. recta, T. superba, and T. diadema are also Plumarella.

Evolutionary dynamics of a common sub-Antarctic octocoral family

“…Thouarella species were recently spilt into two species groupsGroup 1 species have isolated polyps and Group 2 has polyps in whorls (Taylor et al, 2013a). The historical taxonomic groupings of 'Antarctica' and 'Köllikeri' species are not separate in the presented phylogenies making the recent merging of these groups (discussed in Taylor et al, 2013a) into Group 1 (species with isolated polyps) supported by this phylogenetic analysis.…”

“…The historical taxonomic groupings of 'Antarctica' and 'Köllikeri' species are not separate in the presented phylogenies making the recent merging of these groups (discussed in Taylor et al, 2013a) into Group 1 (species with isolated polyps) supported by this phylogenetic analysis. Only one species from Group 2 (Thouarella coronata) is in this analysis and does not cluster with Group 1 Thouarella; more species are required to comment further on the validity of the Thouarella species groups and if they should be raised to subgenera level.…”

“…However, the non-Antarctic base to the Primnoidae would suggest that the large number of species within the sub-Antarctic is a secondary in situ radiation (Fig. 1, A5); meaning that the sub-Antarctic is not the origin for this speciose family, as has been previously suggested (Cairns and Bayer, 2009;Taylor et al, 2013a). For Primnoidae at least, Antarctica is mostly an evolutionary sink, rather than a source (Crame, 1993;Briggs, 2003), with diffusion from the deep oceans of the tropics to the Antarctic, so-called ''polar emergence'' -as seen in Benthoctopus , the deep-sea holothurian, Elpidia (Mironov et al, 2013), Pleurobranchinae (Göbbeler and Klussmann-Kolb, 2010) and crinoids (Eléaume et al, 2012).…”

“…There have also been three genera revisions: Amphilaphis (Zapata-Guardiola and López-González, 2012); Thouarella (Taylor et al, 2013a); Mirostenella (Zapata- Guardiola et al, 2013), as well as a number of new species additions. There are currently 41 genera and 266 species within Primnoidae (see Table 1).…”

Unrecognized diversity of a scale worm, Polyeunoa laevis (Annelida: Polynoidae), that feeds on soft coral

“…Polyeunoa laevis is considered a specialist, feeding primarily on gorgonian cnidarians (Stiller, 1996) including Thouarella, a widespread soft-coral species commonly called the bottlebrush corals. Even though this genus can be very common, especially in Antarctic and sub-Antarctic waters, species identification and delimitation is problematic (Taylor, Cairns, Agnew, & Rogers, 2013) as morphological features are variable. The association between P. laevis and Thouarella species has been documented in several studies (Barnich et al, 2012;Pettibone, 1969;Stiller, 1996).…”