Remarks. Worms are mostly associated with coral (live and dead) or limestone, although in this study two species were found as foulers in marinas and ports from some localities in South America. The tubes have a tree trunk or leathery appearance with several gold, green olive or brown colored thin layers, from where entire worms are often hard to extract. Chemical composition of tubes has not been studied in Notaulax.
Notaulax is composed of 20 species (Capa et al. 2014). Among the nominal species, only one has been described from South America: N. tilosaula (Schmarda, 1861) n. comb (described as Sabella Linnaeus, 1767, and here is transferred to the genus Notaulax). Notaulax christenseni (Augener, 1932) was described from Adelaide Island, Antarctica, at 620 m depth; Giangrande & Gambi (1997) examined the holotype (ZMO, C547) and revealed that it probably belongs to Notaulax. Unfortunately, Augener (1932) did not illustrate any structures and his description does not include diagnostic features. Thus, the reexamination of types is needed in order to corroborate the genus identity of Augener’s species.
The genus was partially studied by Perkins (1984), but a worldwide revision is required, since many of the original descriptions are incomplete and lack illustrations. In Notaulax, the length of basal lamina, shape of dorsal and ventral flanges, length of palmate membrane, number and distribution of lensed eyespots, and presence of interramal abdominal eyespots (see remarks below for N. tilosaula) are useful features to compare among species, in addition to chaetal structures. Here, N. tilosaula is transferred to the genus Notaulax and redescribed from Valparaiso (Chile), and a new species is described from Puerto Deseado (Argentina).