Stephanollona angusta, Vieira, Leandro M., Gordon, Dennis P., Souza, Facelucia B. C. & Haddad, Maria Angélica, 2010

Vieira, Leandro M., Gordon, Dennis P., Souza, Facelucia B. C. & Haddad, Maria Angélica, 2010, New and little-known cheilostomatous Bryozoa from the south and southeastern Brazilian continental shelf and slope, Zootaxa 2722, pp. 1-53 : 35-37

Stephanollona angusta n. sp.

( Figures 83–86 , Table 17 )

Material examined. Holotype. MZUSP 0 341, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6678. Paratypes. MZUSP 0342–0344, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6678. Additional material. MZUSP 0 345, Brazil, project REVIZEE South SCORE, RV ‘Prof. Wladimir Besnard’, station 6681.

Diagnosis. Colony encrusting; 6 oral spines, orificial sinus widest distally, the condyles slightly set back from the sinus entrance; elongate avicularia narrow, tapering distally; small avicularia with somewhat cucullate rostral rim; ovicell subglobular, smooth with short labellum.

Etymology. Latin angusta , narrow, alluding to the shape of the large avicularia .

Description. Colony encrusting, uni- to multilaminar. Zooids oval to irregularly polygonal; frontal shield smooth, imperforate except for a few medium-sized marginal pores. Orifice rounded, crenulated distally and with two very large downward-facing condyles reaching entrance of U-shaped sinus. Six hollow oral spines; ovicelled zooids with two pairs of lateral spines and two distal spines obscured by ooecium. One or a pair of narrowly elongate avicularia adjacent to orifice, tapering distally with rounded tip, rarely one such avicularium more proximally placed, orientated laterally or obliquely distally; crossbar complete without ligula. Small oval avicularia less common, single or paired, proximal to a large avicularium or a proximolateral spine, the rostral rim somewhat cucullate with a smooth edge, orientated laterally; crossbar complete, thin, aligulate. Ovicell subglobular, hyperstomial, the smooth surface with a rounded frontal excavation; aperture with short labellum flanked by indentations.

Remarks. Only Stephanollona asper ( Canu & Bassler, 1923) has been recorded from Brazil previously ( Vieira et al. 2008, p. 33), but S. asper has a wider sinus and ligulate avicularia (see Winston 2005, p. 113) compared to S. angusta n. sp. Recently described Stephanollona propinqua Winston & Woollacott, 2009 differs from the two species described here in the morphology of the orifice.

Stephanollona angusta differs from Stephanollona arborescens , described below, by the shape and size of the autozooids, the shape of the orificial condyles and sinus, and the shape and disposition of the avicularia . The mature colony of S. arborescens is erect with a granular-tubercular surface.

Distribution. Brazil: off São Paulo state, 99–168 m (present study).

Figures

FIGURES 83 – 86. Stephanollona angusta n. sp., MZUSP 342 (part of the paratype specimen), off São Paulo, Brazil. 83, Some zooids of colony; 84, autozooid with two kinds of adventitious avicularia; 85, close-up of ovicell with small rounded pore; 86, close-up of orifice with six oral spines.

Tables

TABLE 17. Measurements (in mm) of Stephanollona angusta n. sp.

	n min–max	mean	SD
Autozooid length	20 0.383–0.556	0.454	0.044
Autozooid width	20 0.309–0.531	0.411	0.055
Orifice length	20 0.086–0.111	0.098	0.008
Orifice width	20 0.093–0.111	0.102	0.006
Spatulate avicularium length	20 0.198–0.309	0.263	0.028
Spatulate avicularium width	20 0.049–0.086	0.069	0.011
Ovicell length	20 0.173–0.222	0.195	0.013
Ovicell width	20 0.161–0.210	0.182	0.011