Osthimosia incisa n. sp. (FIg. 17; TAbLE 19) Etymology. LATIN ‘ incisus ’, CUT INTO, ALLUDINg TO THE DEEPLY INCISED SINUS OF THE AUTOZOOIDAL ORIFICE. Material examined. HΟlΟtype: CRBA-58251, STN PAT1208DR12 (SAMPLE COATED WITH gOLD), COLONY C. 8 MM LONg, 5 MM WIDE. Description. COLONY CYLINDRICAL, WITH AUTOZOOIDAL PERISTOMES PROjECTINg AbOVE COLONY SURFACE; COLONY SIZE C. 8 MM LONg bY 5 MM WIDE. AUTOZOOIDS CONVEX, WITH DISTINCT bOUNDARIES; FRONTAL WALL WITH NUMEROUS LARgE MARgINAL PORES. PRIMARY ORIFICE LONgER THAN WIDE, A DEEP, V-SHAPED SINUS COMPRISINg MORE THAN ONE-THIRD OF ITS TOTAL LENgTH; CONDYLES DEEP, PROMINENT. PERISTOME WELL DEVELOPED, RISINg FROM LATERAL bORDERS OF ORIFICE TO ENVELOP A SMALL, COLUMNAR PROXIMAL SUbORAL AVICULARIUM THAT ObSCURES THE PRIMARY ORIFICE; THE ROSTRUM bROADLY OVAL, SLENDER CROSSbAR WITHOUT A COLUMELLA, ACUTE TO PLANE OF ORIFICE, PROXIMALLY DIRECTED. OVICELL HYPERSTOMIAL, SPHERICAL, PROMINENT, SMOOTH, WITH A SMALL OVAL FRONTAL FENESTRA. LARgE VICARIOUS AVICULARIA FREqUENT, AS LARgE AS AUTOZOOIDS, WITH bROADLY SPATULATE DISTALLY HOODED ROSTRUM; SLENDER CROSSbAR, PALATAL FORAMEN EXTENDINg TO HOODED DISTAL PORTION OF ROSTRUM. Remarks. OsthimΟsia incisa n. sp. RESEMbLES O. multifaria HAYWARD & WINSTON, 2011 IN THE SMALL, COLUMNAR, PROXIMAL SUbORAL AVICULARIUM. IT DIFFERS IN THE V-SHAPED SINUS, THE SMALL OVAL FRONTAL FENESTRA AND IN THE AbSENCE OF VARIAbLY SIZED VICARIOUS AVICULARIA. THERE ARE A NUMbER OF SIMILARITIES WITH O. magna MOYANO, 1974 FROM SOUTHERN CHILE, bUT THE SINUS IS PROPORTIONATELY SHORTER IN THIS SPECIES; INDEED, MOYANO DESCRIbED THE ORIFICE AS ALMOST CIRCULAR, PROVIDED WITH A SHORT AND RELATIVELY WIDE SINUS, WHICH, PUZZLINgLY, DIFFERS FROM HIS ILLUSTRATION. n, number of measurements made; SD, standard deviation

Published as part of Figuerola, Blanca, Gordon, Dennis P. & Cristobo, Javier, 2018, New deep Cheilostomata (Bryozoa) species from the Southwestern Atlantic: shedding light in the dark, pp. 211-249 in Zootaxa 4375 (2) on pages 238-239, DOI: 10.11646/zootaxa.4375.2.3, http://zenodo.org/record/1298290