radiolaria - rads_cat - Stichocorys seriata

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Stichocorys seriata

Citation: Stichocorys seriata Jørgensen 1905

A many-jointed form. The uppermost joints are convex and increase in size so that the diameter of the fifth is from three to four times as great as that of the first. The lower part is more or less distinctly cylindrical. On the cephalis, there is a short broad tophorn. The pores below are roundish rectangular, in very distinct, regular, horizontal rows. The number of the joints varies, probably according to age. Uppermost there is a low, semispherical (or broader) cephalis, then short joints, which increase evenly in width up to the fourth or fifth, which is usually the broadest. From the sixth joint, which is decidedly narrower, the width decreases, but very slowly, so that the lower part is almost cylindrical, only a little narrower below. I have not seen more than eight joints. These lower joints in the cylindrical part are not plainly divided off from each other. The upper part of the shell is shaped like a high cone. There is a short, broad, three-edged (?) tophorn protruding from an inner skeleton in the two upper joints. It is not easy to see these inner skeleton parts which are, at all events, in a high degree retrograded, for it is a difficult matter to examine the shell from the open end, and the outer lattice shell in side view hides the short, primary spines. So I have not been able definitely to decide whether this genus has the same primary skeleton parts as the foregoing ones. Neither have I been sure if protruding basal spines exist in the two upper joints (the apical spine only excepted).The shape of the cephalis in some positions of the lattice shell might suggest that also inner primary arches are to be found, and not only the primary spines. It is doubtful whether there is a protruding ventral, sagittal spine. On the other hand, a long, inner axial spine is plainly visible. It seems to consist of three or more long, parallel branches, which reach down through more than half the length of the lattice shell. The central capsule also reaches far down through the shell. The pores on the cephalis are small, round, widely apart and scattered. On the second joint, they are perhaps a little larger, on the third somewhat smaller again, and from here they are regularly placed in horizontal rows. From the fourth joint and downwards, the pores become more irregular in form and size, from quite small and round to rather large, roundish rectangular in shape, although generally speaking they are small and always in regular, horizontal rows. On the cylindrical lower part, they are also placed in more irregular vertical rows. The average size of the pores does not increase, at any rate noticeably, from the fourth joint downwards. This species varies rather considerably. For instance, its greatest width may be either in the fourth or fifth joint, and there are often irregular contractions in the lower part. It is doubtful whether any of the individuals illustrated are fully developed. On the best developed specimen (Jørgensen 1905, fig. 102) the lower margin was regularly dentate. Often young individuals may be found consisting of only a few joints and entirely without the cylindrical lower part.

Height, up to 128µ, greatest width 72µ. Pores, up to 6µ.

Remarks: The species resembles the one illustrated by Cleve (1899, pl. 2, figs. 5-6), which he calls Lithomitra australis EHRB. It is probable that the same basal spines are present in this species, protruding as fine needles, as in Androcyclas gamphonycha and Clathrocyclas craspedota. Even if these spines are present, Haeckel's name for the genus might in this case be retained without any great disadvantage. Rather rare, always in small numbers and only in deep water samples.

Distribution: In surface samples, 2/2 1901, off Søndmøre, 13/2 off Lofoten and 5/3 off Finmark. Most probably a boreal oceanic species.

Clearly an artostrobid and thus not a Stichocorys. Caulet placed in Botryostrobus. See also Matsuzaki 2015 -dbl

References:

Gran, H. H. (1902). Das Plankton des norwegischen Nordmeeres von biologischen und hydrographischen Gesichtspunkten behandelt. Report Norwegian Fishery and Marine Investigations. 2, pt. 2(5): 1-222. gs

Jørgensen, E (1905). The protist plankton and diatoms in bottom samples: Radiolaria. In, Nordgaard (ed.) Hydrographical and biological investigation in Norwegian Fjord. 49-151. gs O

CATALOG OF ORIGINAL DESCRIPTIONS: Stichocorys seriata Jørgensen 1905

Stichocorys seriata

References:

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