Ophthalmidium aff. balkwilli

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Mynd: Guðmundur Guðmundsson

Cornuloculina aff. balkwilli (Plesiotype from sample Bioice3282: depth 1813m; bottom water temp. 2,54°C; loc. 62,8°N, -16,2556°W Dec.Degr.)

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Mynd: Guðmundur Guðmundsson

Hæð stöpla svarar til fjölda sýna þar sem tegundin er: fágæt (1-2 eintök); sjaldgæf (3-8 eintök); alltíð (9-32 eintök); algeng (>32 eintök). Gögn úr botndýraverkefninu (Bioice). (ENGLISH- Column height represents number of samples in bins where the species is: rare (1-2 specimens); occasional (3-8 specimens); common (9-32 specimens); and abundant (>32 specimens.) Data from the Bioice programme.)

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Mynd: Guðmundur Guðmundsson

Dreifing tegundar eftir dýpi, seltu og sjávarhita, innan þess breytileika sem allar sýnatökustöðvar ná yfir, sýnt sem heildarspönn lóðréttra ása. Gögn úr botndýraverkefninu „BIOICE“. (ENGLISH – Occurrence zone of the species within the range of water depth, temperature, and salinity, spanned by the "Bioice" samples; demarcated by respective y-axes.)

Almennt

Ophthalmidium aff. balkwilli Mcfayded, 1939

Ophthalmidium blackwilli – Mcfayden, W.A., 1939 [aff]. On Ophthalmidium, and two new names for Recent foraminifera of the family Ophthalmidiidae. Journ. Royal Microsc. Soc. London, ser.3, vol.59, p.166. 

Description: Chamber arrangement is planispiral; comprising up to 12 windings of tubular chambers. Proloculus (30-40 µm in diameter) is followed by a closely coiled spiral tube, which may comprise from over two to four windings; succeeded by up to eight or nine tubular segments, which gradually decreasing in length from less than two windings, to one third or fourth of a whorl. As a result the sutures are somewhat irregularly dispersed along the spire. Initial chambers are tubular with a uniform diameter; later and larger chambers become successively more flattened. The periphery of the latest windings has a thin and semi-transparent wing along the outer margin only, bordered with a thickened outer rim. Aperture is circular to elongated, with somewhat thickened and everted lip; the septa cut obliquely across successive whorls. Surface is smooth and sutures are depressed. The largest specimen is 1,4 mm in diameter, but most are less than 1 mm. About 70 specimens were picked from 34 of the 1031 Bioice samples that were checked for forams and in four miscellaneous samples. 

Diagnosis: This species resembles superficially Ophthalmidium inconstans, but is different in lacking peripheral wings of the initial whorls, and in that the latest adult chambers have a thin wing along the outer margin only, with a thickened rim along the outer margin.

Gudmundur Gudmundsson, IINH (gg@ni.is)

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Útbreiðsla Ophthalmidium aff. balkwilli (Bioice samples, red dots; miscellaneous IINH samples, blue dots)

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