Melicerita brasiliensis Vieira, Gordon, Souza & Haddad, 2010, n. sp.

Melicerita brasiliensis n. sp.

(Figures 17, 19 –21, Table 6)

Material examined. Holotype. MZUSP 0 282, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6661. Paratypes. MZUSP 0 283, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6776. MZUSP 0 284, station 6779. MZUSP 0 285, station 6782. MZUSP 0 429, station 6661. Additional material. MZUSP 0 286, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, indetermined station. MZUSP 0 287, station 6662. MZUSP 0 288, station 6669. MZUSP 0 289, station 6776. MZUSP 0 290, station 6778. MZUSP 0 291, station 6787.

Diagnosis. Colony erect, bilaminar; autozooids diamond-shaped, with coarsely granular cryptocyst; pair of denticles in proximal corners of opesia, with distal denticles linked by a ridge; small avicularia along branch margins.

Etymology. The species name alludes to the first record of the genus in Brazilian waters.

Description. Colony erect, bilaminar, up to 11 mm high, attached by chitinous rhizoids. Autozooids diamond-shaped, in alternating transverse rows, separated by raised ridges; cryptocyst flat, coarsely granular; neanic zooids with frontal surface smooth. Opesia in distal half of zooid, D-shaped, with straight proximal border slightly raised. A pair of triangular denticles present in proximal corners of opesia; distal denticles smaller, linked by a thin ridge. Avicularia small, present along branch margins, often replaced by small kenozooids with small orifice; small rostrum frontally directed, smooth, with complete crossbar; mandible 4.4 times wider than long. Ovicell immersed with semielliptical aperture, distal to maternal autozooid; two weakly porous areas distolateral to the orifice, with longitudinal series of small irregular pores.

Remarks. Recent species of Melicerita Milne Edwards, 1836 have been recorded from the southern hemisphere, usually in deeper waters of the Antarctic region (Hayward 1995). Only two species were previously recorded from the continental shelf of South America (Patagonia) ― Melicerita atlantica Busk, 1884 and Melicerita blancoae López Gappa, 1981a; both are characterized by near-medial opesiae and the absence of avicularia. Infertile Melicerita sp. (Fig. 18) from station 661 differs in having wider stems with hexagonal zooids and more rounded avicularia

Moyano (1997) gave a table with comparative features of Recent species of Melicerita, giving the distinguishing features of the avicularia, opesial denticles and rhizoids. Five species were described with four opesial denticles, but at least three ― viz. Melicerita angustiloba Tenison-Woods, 1862, M. ligulata Liu & Hu, 1991 and M. subantarctica d’Hondt, 1984 ― differ in the shape of the opesia and absence of avicularia; the shape of the autozooid and opesia of M. brasiliensis are similar to those described for M. blancoae, as is the presence of proximal and distal denticles in the opesia. However, M. brasiliensis has small avicularia along colony margins that are often replaced by small kenozooids, and by the shape of ooecial apertures and their smaller lateral porous areas with pores weakly developed in comparison to other species.

Distribution. Brazil: off São Paulo and Santa Catarina states, 100–480 m (present study).