Stylopoma anacarolinae, Rodrigues & Larré & Vieira, 2024

Rodrigues, Maria J. S., Larré, Igor R. N. M. & Vieira, Leandro M., 2024, Two new species of Stylopoma (Bryozoa, Cheilostomatida) from the Southwestern Atlantic, Zootaxa 5512 (3), pp. 420-434 : 422-426

Stylopoma anacarolinae sp. nov.

urn:lsid:zoobank.org:act:

( Figs 2A–F, 3A–F; Tables 1, 2, 3)

Material examined. Holotype: UFPE 2596 , single colony on calcareous nodule (with four fragments mounted on stubs), off Coruripe , Alagoas, Brazil, 10º16’40’’ S, 36º11’20’’ W, 13 m, coll. 1965 by ‘Akaroa’, stn. 90 . Paratypes: UFPE 241 , Taíba , São Gonçalo do Amarante, Ceará, Brazil, 02°50’53” S, 39°59’42’’ W, coll. 2011 ; UFPE 243 , Japu , Coruripe, Alagoas, Brazil, 10°16’40’’ S, 36°11’20’’ W, 13 m, coll. 1965 by ‘ Akaroa’, stn. 90 ; UFPE 389 , Jatiúca , Maceió, Alagoas, Brazil, 09°39’10’’ S, 35°41’40’’ W, 0–3 m, coll. 2003 by L.M. Vieira ; UFPE 3074 , Francês , Marechal Deodoro, Alagoas, Brazil, 09°46’11’’ S, 35°50’21’’ W, 0–3 m, coll. 2003 by L.M. Vieira ; UFPE 3075 , Ilha Escalvada , Guarapari, Espírito Santo, Brazil, 20°42’0’’ S, 40°24’23’’ W, 15 m, coll. 2017 by L.M. Vieira .

Diagnosis. Stylopoma with frontal shield bearing 66–106 pseudopores; primary orifice with poster wide and deep U-shaped sinus; condyles squared, with smooth edge; 1–2 adventitious avicularia with a subtriangular rostrum; vicarious avicularium sublanceolate; ooecium with pseudoporous surface and one to four small avicularia on its surface.

Type locality. Off Coruripe , Alagoas, Brazil .

Etymology. The specific name honors Dra. Ana Carolina Sousa de Almeida (Carol) , who helped the authors with comparative material during the master’s thesis of the first author.

Description. Colony encrusting, unilaminar to multilaminar. Autozooids rectangular to irregularly polygonal ( Figs 2A, 3A), limited by shallow lateral walls ( Figs 2B, 3B). Frontal shield with some small granules of calcification on the surface ( Fig. 3B), 66–106 frontal small pseudopores varying in size throughout the colony, often placed in irregularly polygonal deep cavities on the zooidal surface ( Fig. 2B, C), and distinctly large, elongated marginal pores with secondary calcification; umbo absent. Primary orifice with anter transversely D-shaped ( Figs 2B, C; 3B), wider than long, with a smooth distal rim and poster with a wide and deep U-shaped median sinus ( 0.032 –0.049 mm length x 0.026 –0.041 mm width) about 1/3 of the orifice length; a pair of slightly projected square condyles ( 0.008 –0.014 mm length x 0.014 –0.022 mm width), with smooth margins. Secondary orifice slightly raised, with nodular calcification around the primary orifice ( Fig. 3B). Adventitious avicularium small ( 0.051 –0.075 mm length x 0.035 –0.054 mm width) ( Figs 2B, C; 3B), single or paired, placed proximolateral to the orifice or sub-oral ( Figs 2C; 3B), distolaterally oriented; 1–2 frontal avicularia, placed below the orifice ( Fig. 2B) or adjacent to the zooidal margins, irregularly oriented; avicularia with subtriangular rostrum, a thin and complete crossbar and an elliptical foramen. Vicarious avicularia large ( 0.366 –0.449 mm length x 0.105 –0.137 mm width) ( Figs 2D; 3C), sometimes larger than the autozooid, rostrum sublanceolate (but sometimes almost panduriform); palate incomplete medially and distally, fusing at the distal third and leaving a median and a distal foramen; foramen elliptical and elongated; complete crossbar. Vicarious kenozooids may be present between autozooids ( Fig. 3A). Ovicells prominent ( Figs 2E, F; 3D–F), obscuring the orifice of the maternal zooid; ooecium globose, slightly flattened frontally ( Fig. 3E), with more pseudopores compared to the frontal shield; one to four small adventitious avicularia of the same morphology as the others on the ooecial surface ( Figs 2E, F; 3D–F); opening of the ooecium semicircular, with a joined proximal labellum ( Fig. 3E, F).

Remarks. In some colonies of Stylopoma anacarolinae sp. nov., most autozooids lack adventitious avicularia, which may represent ontogenetic variability ( Fig. 3A). In these colonies, orifice and sinus shapes serve as useful characters to give a more confident identification.

Autozooids of S. anacarolinae sp. nov. have an orifice with a D-shaped anter and poster with a U-shaped sinus, a characteristic shared with ten other Stylopoma species. However, S. anacarolinae sp. nov. is distinguished from other species with a U-shaped sinus in having a pair of squared condyles. Among the species described from Brazil, at least four, namely S. aurantiacum , S. hastata , S. multiavicularia and S. variabilis , have orifices with a U-shaped sinus. Besides differences in the shape of the condyles (triangular in S. hastata , and subrectangular in S. aurantiacum , S. multiavicularia and S. variabilis ), these species are distinguished from S. anacarolinae sp. nov. by the width of the sinus, which is broader in Stylopoma anacarolinae sp. nov. compared to the congeners ( Canu & Bassler 1928a; Ramalho et al. 2018; Rodrigues et al. 2020).

Morphologically, S. faceluciae , described from Brazil (Costa dos Coqueiros and Todos os Santos Bay; Rodrigues et al. 2020) resembles S. anacarolinae sp. nov. due to the presence of an orifice with squared condyles and sublanceolate vicarious avicularia. However, it can be distinguished from the latter by the shape of the sinus (teardrop-shaped in S. faceluciae and broadly U-shaped in S. anacarolinae sp. nov.).

Distribution. Endemic; known from NE and SE Brazil ( Ceará, Alagoas and Espírito Santo), 0–15 m depth, growing on hard substrates (calcareous nodules and stones).