Nannotax3 - ntax_Farinacci - Chrysochromulina megacylindra

Original descriptions of taxa. For coccolithophores, and many calcispheres, these are pages from the Farinacci & Howe Catalog of Calcareous Nannofossils. In other cases (e.g. non-calcifying haptophytes) the data is directly compiled on this site. The "Catalogue of Calcareous Nannofossils" was originally compiled by Prof A. Farinacci 1969-1989, since 2000 it has been updated and extended by Richard Howe - see The Farinacci and Howe Catalog - an Introduction.
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Citation: Chrysochromulina megacylindra Leadbeater 1972

Type specimens: Type drawing Fig. 1D

Type sample (& lithostrat): Found on 8 Aug. 1970 in a sea water sample taken from a depth of 5 m

Standardised type level: 160_HOLOCENE

Type locality: approximately 30 km NW of Bergen

Farinacci catalog page (& compiler): n/a

Current citation: Chrysochromulina megacylindra Leadbeater 1972

Cell conical, 5 µm long x 4 µm wide; flagella 2 equal, 20 µm long and a haptonema 18 µm long when extended. Scales of two types, inner, plate-like subcircular with a slightly thickened margin, diameter 1.0 µm, with a pattern of radiating ridges and an inconspicuous cruciform plane centre visible on both surfaces, but a thin band of concentrically striated material at the edge of the distal surface. Outer scales cylindrical, each cylinder straight-sided, very thin, diameter 0.5 µm, length 1.0 µm, attached to the outer surface of a base plate diameter 0.7 µm.

Cellula conica, 5 µm longa, 4 µm lata; flagella 2 aequalia, 20 µm longa; haptonema extensum 18 µm longllm. Squamae dimorphae. Squama strati interioris laminaris, suborbicularis, margine paulum incrassata, 1.0 µm diam., exili area centrali cruciformi plana, circum eam carinis radiantibus utrinque visibiZibus ornata, clava tenui concentrice striata ultimas partes carinarum extra obtegente. Squama strati exterioris cylindrica, lateribus rectis, tenuissima, 0.5 µm diam., l.0 µm longa, e lamina basali 0.7 µm diam. oriens.

C. megacylindra was frequently found in plankton samples from Hjeltefjorden, occasionally in samples from Herdlefjorden, and frequently in culture (for further details see LEADBEATER 1972). It was one of the commonest species of Chrysochromulina observed in most preparations.

The conical cell, approximately 5 µm long, possesses two flagella and a haptonema of similar length (Figs. lD, 4, 5). In shadowcast whole mounts this species is readily recognised by its highly characteristic cylinder scales combined with moderately large plate scales. The proximal surfaces of the plate scales bear a pattern of ridges arranged in quadrants and radiating from a cruciform centre

(Fig. 6). A similar pattern of radiating ridges can be seen on the distal surface but is obscured at the periphery by a band of concentric ridges (Fig. 7). The extreme edge is slightly raised. The cylinder scales consist of a circular base plate and a thin straight-sided cylinder (Figs. 7-9) attached to it submarginally. The proximal surface of the base plate displays a pattern of radiating ridges similar in appearance to those of the proximal surface of the plate scales (Fig. 7). Towards the periphery there is a circular ridge and beyond this the radiating ridges are more pronounced. The patterning of radial ridges on the distal surface is similar to that on the proximal surface (Fig. 8) though it is slightly less distinct at the margin; a circular ridge surrounds a large central aperture through which, in complete scales, the cylinder is inserted. Because the cylinders become flattened during the preparation of whole mounts they appear to be wider than the base plates. However, sections (e.g. Fig. 9) show that the cylinder is attached to the lower layer of the base plate a short distance inwards from the periphery.

References:

Leadbeater, B. S. C. (1972a). Fine structural observations on six new species of Chrysochromulina (Haptophyceae) from Norway with preliminary observations on scale production in C. microcylindra sp. nov. Sarsia. 49: 65-80. gs

Leadbeater, B. S. C. (1972b). Identification, by means of electron microscopy, of nanoplankton flagellates from the coast of Norway. Sarsia. 49: 105-132. gs

CATALOG - Chrysochromulina megacylindra

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