(Cornuloculina inconstans)

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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Biota

Tegund (Species)
(Cornuloculina inconstans)