Critical to understanding the correct name of the common fouling species of Watersipora is establishing the identity of W. subtorquata (d’Orbigny, 1852). Specimens of a bryozoan from Rio de Janeiro described by d’Orbigny (1842) as Escharina torquata (Lamouroux, 1825) were later renamed by him (d’Orbigny 1852, p. 399) as Cellepora subtorquata, presumably to avoid homonymy with another species he referred to as Cellepora torquata (Quoy & Gaimard, 1827) (see d’Orbigny 1852, p. 403). Waters (1879) synonymised d’Orbigny’s Cellepora subtorquata with Lepralia cucullata Busk, 1854 but inexplicably applied the name of the junior synonym L. cucullata for his specimens from Naples. The first revision of d’Orbigny’s type was undertaken subsequently by Waters (1905) who studied d’Orbigny’s material deposited at the MNHN. He noted the high quality of d’Orbigny’s original figures but remarked that, in the original specimens, the projecting lateral wings on each side of the sinus were more developed than those depicted by d’Orbigny (1842). Taylor & Gordon (2002) reviewed the bryozoan work of Alcide d’Orbigny (1802–1857), publishing a scanning electron micrograph of d’Orbigny’s type specimen (Taylor & Gordon 2002, fig. 1C) in which it is possible to recognize some of the diagnostic features (orifice shape and frontal pseudopores) depicted in the original figures of this species. The type specimen of d’Orbigny (MNHN, d’Orbigny Collection 13637) (Figs 1–5) comprises a large colony with some intact opercula (Figs 1–2); the projecting proximolateral wings are well developed in most zooids (Fig. 4), as observed by Waters (1905), but with increasing calcification can become obscured, shallow and inconspicuous in frontal views of the orifice (Figs 3, 5). The subcircular orifice (Fig. 5) was well figured in d’Orbigny’s plates; the orifice is slightly wider than long, with a U-shaped sinus demarcated by triangular condyles that project distomedially.

Comparisons of d’Orbigny’s type specimen and the specimens identified by Marcus (1937, 1938) from Brazil under the name Watersipora cucullata (NHMUK 1948.2.16.18, and uncatalogued specimens deposited at MZUSP) indicate that they represent the same species, as has been suggested by Gordon (1989) and Ryland et al. (2009). Marcus (1937, pl. 24, fig. 63A, B) showed the orifice to have well-developed proximolateral wings in Brazilian colonies. In addition, the operculum in the Brazilian specimens is characterized by a parallel-sided dark band of two proximal lucidae adjacent to the condyles (Marcus 1937, pl. 24, fig. 63A, B). The same operculum shape and lucidae were observed in Rio de Janeiro specimens figured by Ramalho et al. (2009, fig. 3D) in material they named Watersipora subovoidea. Ramalho et al. (2011) followed Ryland et al. (2009) in using the name W. subovoidea for specimens with “triangular, tooth-like condyles, located distomedially [sic], and a strongly pigmented operculum with a parallel-sided dark central band”. All characteristics described for W. subovoidea by Ryland et al. (2009) suggest that their specimens actually belong to W. subtorquata, and restudy of the material they analyzed (NHMUK 2007.12.14.2–8) confirms this supposition. However, neither figures nor descriptions of Busk’s type specimen of Lepralia cucullata (NHMUK 1854.11.15.189), designated by Ryland et al. (2009: 54) as the neotype of Watersipora subovoidea, were given by Ryland et al. (2009), a situation which we rectify below.