Bellactis ilkalyseae Dube, 1983

(Figs. 17 –19, Table 6)

Bellactis ilkalyseae Dube, 1974 (nomen nudum) Bellactis ilkalyseae Dube, 1983

Bellactis ilkalysae [sic]: Gasparini et al. 2005 Material examined. (See Appendix 1).

Description. External anatomy (Fig. 17): Pedal disc to 10 mm diameter in preserved specimens, wider than column. Column elongate, not divisible into regions, to 22 mm height and to 10 mm diameter in preserved specimens. Cinclides not numerous, in mid-column, in 3–4 rows (Figs. 17 B, D). Mesenterial insertions visible. Oral disc to 20 mm diameter in preserved specimens. Tentacles to ~204, smooth, tapering toward tips, 2–3 mm length in preserved specimens; irregularly arranged (Fig. 17 C).

Internal anatomy and microanatomy (Fig. 18): Marginal sphincter muscle mesogleal, diffuse, very weak, alveolar (Fig. 18 E). Mesenteries irregularly arranged in four cycles. First cycle perfect, with 7 pairs of mesenteries; second (6 pairs) and third (~28 pairs) cycles imperfect; fourth cycle only proximally. First and second cycles fertile, including directives. Two pairs of directives each associated with a siphonoglyph. Retractor muscles restricted (Fig. 18 A). Parietobasilar muscles poorly developed. Longitudinal muscles of tentacles ectodermal (Fig. 18 B). Relatively strong longitudinal ectodermal muscles in distal end of column (Fig. 18 B). Basilar muscles well differentiated, with fibers on short and thick mesogleal pennon (Fig. 18 D). Acontia very numerous, long and thick.

Color (Fig. 17): Living specimens with column whitish-translucent; tentacles with yellow tips, grey-bluish with irregular spots proximally (Figs. 17 A, B). Preserved specimens with uniform yellowish column and slightly darker tentacles (Figs. 17 C, B).

Cnidom: Spirocysts, basitrichs, microbasic b -mastigophores and p -amastigophores (Fig. 19). See Table 6 for size and distribution.

FIGURE 19. Cnidae of Bellactis ilkalyseae . A, C, F, I, K, L, N, O) Microbasic p -amastigophores. B, D, G, J, M, P) Basitrichs. E) Microbasic b -mastigophore. H) Spirocyst.

Geographic and bathymetric distribution. Bellactis ilkalyseae is distributed in the coast of Brazil (Fautin 2013). This is an intertidal species found between 0– 2 m.

Taxonomic remarks. Bellactis was originally placed within the family Sagartiidae (Dube 1983) . However, general external and internal anatomy (particularly the presence of ectodermal longitudinal muscle along distal column) and the cnidom correspond with those of Aiptasiidae .

Our specimens agree well with the original description of the species (Dube 1983) except in the mesogleal marginal sphincter. Dube (1983) described the marginal sphincter as strong, but our specimens show a very weak marginal sphincter muscle (Fig. 18 E). We modified the diagnosis of the genus to reflect this. In addition, Dube (1983) described the retractor muscles as diffuse and relatively weak whereas in our specimens these muscles are relatively strong and restricted.

TABLE 6. Size ranges of the cnidae of Bellactis ilkalyseae . x, mean; SD, standard deviation; S, ratio of number of specimens in which each cnida was found to number of specimens examined; N, Total number of capsules measured; F, frequency; +++, very common; ++, common; +, rather common; Abbreviations: M, Microbasic.