Aptonella violacea Canu & Bassler, 1928

Larré, Igor R. N. M., Almeida, Ana C. S. & Vieira, Leandro M., 2024, On some colorful bryozoans from Brazil: reevaluation of Aptonella violacea Canu & Bassler, 1928 and a new species of Cosciniopsis Canu & Bassler, 1927, Zootaxa 5506 (2), pp. 245-260 : 247

Classification of Aptonella violacea Canu & Bassler, 1928

The status of the genus Aptonella has been a subject of discussion throughout the 20 th and early 21 st centuries, particularly regarding the distinctive purplish to reddish pigmentation of its cystid. This characteristic suggests a similarity with Cosciniopsis (e.g., Harmer 1957; Tilbrook et al. 2001). Cosciniopsis was established for Cosciniopsis coelatus Canu & Bassler, 1927 , known for its hyperstomial ovicell closed by the operculum (cleithral; cf. Ostrovsky 2008) and a pseudoporous frontal wall identical to the ovicell surface. These features are readily observable in the syntype of C. coelatus illustrated by Tilbrook (2006, p. 237, pl. 52a–c), making it morphologically distinct from the type material of A. violacea ( Fig. 2 ), which exhibits an ovicell with an opening above the operculum (acleithral; cf. Ostrovsky 2008).

Hastings (1930) reported A. violacea in the Gorgona Island, Colombia (Pacific Ocean), highlighting variations in zooid and operculum sizes compared to Brazilian specimens. Later, Cook (1985) identified specimens along the coast of Ghana as A. violacea and assigned two species as junior synonyms: Gephyrophora rubra Osburn, 1940 , described from Puerto Rico, and Cycloperiella rosacea Osburn, 1947 , described from the Colombian and Venezuelan Caribbean. These species were also characterized by their reddish to pinkish pigmentation.

In the illustration and description of the type specimen of Ge. rubra , the ovicells are unknown, and the paired avicularia are positioned in the latero-oral region with the rostrum converging over the orifice ( Osburn 1940), a characteristic not reported in A. violacea . Winston & Jackson (2021) recorded some specimens from Jamaica and illustrated the ovicells showing an acleithral opening but found no evidence of them being cormidial. According to Osburn (1947), the type material of Cy. rosacea presents a single broken ovicell, but other described and illustrated characteristics indicate a congeneric relationship with A. violacea .

Cook (1985) suggested that a third reddish-pigmented species, Cycloperiella rubra Canu & Bassler, 1923 , described for Miocene and Pliocene of the southeastern USA and Jamaica, might be synonymous or congeneric with A. violacea . The syntype of Cy. rubra , as illustrated by Di Martino et al. (2019, p. 42, fig. 35), exhibits similarities with A. violacea . Consequently, the morphological characteristics observed in Cy. rubra (cf. Di Martino et al. 2019) suggest that the genus Cycloperiella is a senior synonym of Aptonella . The morphological characterization of Cycloperiella violacea n. comb. is presented below, along with comments on the classification of the species concerning morphologically related genera.

Furthermore, considering the differences between the genus Cycloperiella and other genera in the family Stomachetosellidae Canu & Bassler, 1917 , we recommend transferring the genus to the family Bitectiporidae MacGillivray, 1895 , based on the morphological characteristics of the ovicell (see below).

Figures

FIGURE 2. Cycloperiella violacea (Canu & Bassler, 1928) n. comb., USNM 8556, Lectotype, Rio de Janeiro, Brazil. A, B. General view of the colony. C. Detail of zooids with partially damaged ovicells. D. Cormidial ovicell (dashed arrow), latero-oral adventitious avicularium (arrow), and raised peristome on ovicelled zooid forming a pseudosinus. Scale bars: A, B = 500 µm; C, D = 200 µm.