Osthimosia incisa, Figuerola & Gordon & Cristobo, 2018

Figuerola, Blanca, Gordon, Dennis P. & Cristobo, Javier, 2018, New deep Cheilostomata (Bryozoa) species from the Southwestern Atlantic: shedding light in the dark, Zootaxa 4375 (2), pp. 211-249 : 238-239

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

Figures

FIGURE 17. Osthimosia incisa n. sp., HOLOTYPE.A, PORTION OF THE COLONY; B, PROFILE VIEW TO SHOW THE SUbORAL AVICULARIUM;C, DETAIL OF THE PRIMARY ORIFICE;D, DETAIL OF AN AUTOZOOID WITH AVICULARIUM;E, DETAIL OF THE LARGE VICARIOUS AVICULARIUM;F, DETAIL OF THE OVICELL.SCALE bARS:A, 1 MM; B, 200 ΜM;C–F, 100 ΜM.