Thouarella (Cairns & Bayer, 2009)

TAYLOR, M. L., CAIRNS, S. D., AGNEW, D. J. & ROGERS, A. D., 2013, <strong> A revision of the genus <em> Thouarella </ em> Gray, 1870 (Octocorallia: Primnoidae), including an illustrated dichotomous key, a new species description, and comments on <em> Plumarella </ em> Gray, 1870 and <em> Dasystenella </ em>, Versluys, 1906 </ strong>, Zootaxa 3602 (1), pp. 1-105 : 9

Thouarella morphology and characters

Branching structure

The most common Thouarella branching structure is a bottlebrush form, with branchlets arranged on all sides of the main stem in at least three directions. Thouarella species are also pinnate (featherlike branching with branchlets on each side of branch), pinnate to bipinnate (pinnate branching where branchlets are also pinnately branched), dichotomous (repeated bifurcation of branching; Bayer et al. 1983) and bilateral to bottlebrush (where branchlets occur in at least three directions, and are thus technically bottlebrush, however branchlets can curve into one plane creating a bilateral appearance). Part of the colony of T. coronata is also considered to be sympodially branched (the main axis being formed by the basal sections of lateral branches, often forming a zigzag). In some instances, overall colony structure can be one shape and branching structure different, for example, T. hilgendorfi has a uniplanar, flabellate colony shape yet individual bottlebrush branches and branchlets.

The complex morphological structure of Thouarella makes these octocorals ideal habitat for many species of epifauna. In this study specimens of Thouarella were often found harbouring polychaetes along their stem between branchlet planes, brittlestars clinging to branchlet tips, amphipods wedged between polyps, and egg cases and ascidians attached to stems and branchlets ( Fig. 2 ).

Figures

FIGURE 2. Animals found within the branchlets of Thouarella specimens: a) Polychaete found along stem of the holotype of T. affinis; b) crinoid arboreal cup in branchlets of T. crenelata (ZSL AE57); c) anemone attached to branchlet of specimen of T. variabilis (SMF, MD42, sta. 22).