Cornuloculina inconstans

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Mynd: Guðmundur Guðmundsson

Cornuloculina inconstans (Plesiotypes1-3 from sample Bioice3181: depth 1543m; bottom water temp. 3,53°C; loc. 60,8908°N, -26,8033°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

Cornuloculina inconstans (Brady, 1879)

Cornuloculina inconstans – sensu Jones, R.W., 1994 (part). The Challenger Foraminifera, The Natural History Museum, London, Oxford Univ. Press: p. 20, Pl.12, fig. 5, only.

Description: Chamber arrangemt is initially a loosely coiled planispiral, becoming rectilinear in some of the largest specimens. Proloculus globular (60-80 µm in diameter), followed by a spiral tubular chamber of one or two whorls; then variable number of straight to slightly curved tubular chambers, usually two to three in a whorl, rarely four. Post-embryonic chambers are flattened tubes, slightly inflated at the aboral end and gradually tapering towards the apertural end. Successive chambers are connected such that the narrow apertural passage of a preceding chamber enters sideways into an inflated aboral end of a succeeding chamber. The peripheral margin of the chambers is bordered with extremely thin, semi-transparent wings or keels on both sides, separating successive whorls. Rectilinear chambers retain such wings on both sides. Diameter of largest specimen is 3,3 mm, and length of the largest rectilinear fragment is 2,4 mm. Most specimens or fragments are close to 2 mm. About 180 specimens and fragments were picked from 6 of the 1031 Bioice samples that were checked for forams.

Diagnosis: This species differs from Opthalmidium aff. balkwilli in having peripheral wings on both sides of the tubular chambers, and in lacking a thickened keel along the outer margin. All convolutions in C. inconstans, including the embryonic apparatus, are separated by semi-transparent wings, but only the latest segments in O.aff. balkwilli.

Gudmundur Gudmundsson, IINH (gg@ni.is)

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Útbreiðsla Cornuloculina inconstans (Bioice samples, red dots; miscellaneous IINH samples, blue dots)

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