radiolaria - rads_cenozoic - Plagiacantha arachnoides radiolaria - rads_cenozoic - Plagiacantha arachnoides

Plagiacantha arachnoides


Classification: rads_cenozoic -> Plagiacanthidae -> Plagiacanthidae (ss) -> Plagiacantha -> Plagiacantha arachnoides
Sister taxa: P. arachnoides, P. panarium, P. sp.

Taxonomy

Citation: Plagiacantha arachnoides Claparede 1856
taxonomic rank: species
Basionym: Plagiacantha arachnoides
Synonyms:
1855 Acanthometra arachnoides - Claparède p. 675
1858 Plagiacantha arachnoides - Claparède and Lachmann p. 462-463; pl. 22, figs. 8-9
1887 Plectophora arachnoides - Haeckel p. 922
1887 Plagiacantha arachnoides - Haeckel p. 910
1899 Plectophora arachnoides - Cleve p. 31
1905 Plagiacantha arachnoides - Jørgensen p. 129 (not figured)
1914 Plagiacantha arachnoides - Schröder pp. 78-80; figs. 18-19
1987 Plagiacantha arachnoides - Swanberg and Bjørklund fig. 4F
2003 Plagiacantha arachnoides - Bjørklund and Kruglikova p. 245 (not figured)
2003 Plagiacantha arachnoides - Cortese et al. p. 69 (not figured)

Catalog entries: P. arachnoides [no catalog entry yet]

Description


Published descriptions


Cleve 1899 - Acanthometra arachnoides

(p.31) In this species I include also Plagiacantha arachnoides (CLAP. and LACHM.) HKL., which represents the young state. The net-work combining the spines is subject to great variation.


Jørgensen 1905 - Acanthometra arachnoides

In a previous paper (Jørgensen 1900), I have in detail described the structure of this species and shown that, from this structure, it would have to be classified as belonging to Haeckel's genus Plagiocarpa or - the form which is furnished with connecting beams -to Periplecta HCK.At the same time too is mentioned that this structure - as it is explained in the foregoing pages here - is the ground type for a large series of forms. It is likely that still other species are included in the above name. Haeckel's Plectophora arachnoides, can, however, not be distinguished from Plagiacantha arachnoides. In the present material, this species was found only rarely and in small numbers, generally in deep water samples, up to 50 m., only exceptionally near the surface. Almost entirely absent during the diatom inflow.

Distribution: According to Cleve (L. 40, p. 180) a northern form, belonging to Tricho- and Chætoplankton. Frequent on the west coast of Norway, seems also there to be absent during the diatom inflow. In August 1903, numerous between the Faeroe and Shetland Islands and in the sea north of them, near the surface (L. 18, 1903-1904, nr. 1).The species would thus seem to belong to the northern part of the Atlantic, and especially to be abundant in the North Sea and north of Great Britain during the summer months.


Schröder 1914 - Acanthometra arachnoides

Skelett aus drei regulär angeordneten basalstacheln (zwei lateral- und ein dorsalstachel) und einem kleineren apikalstachel besthend. Jeder der drei basalstacheln trägt nahe seinem proximalen ende einen kranz von drei regulär angeordneten ästen, die ungefähr so lang wie der stachel selbst sind, sodass, jeder basalstacheln mit vier ungefähr gleich langen stacheln endigt. Die nach innen und nach unten gerichteten zweigdornen der stacheln sind durch mehr oder weniger zahlreich brückenbalken teils miteinander, teils mit dem mittleren stamm der basalstacheln verbunden. Hierdurch entstehen zahlreiche, teils dreieckige teils fünfeckige grosse maschen (vergl. Jørgensen 1899, seit 72).Der apikalstachel trägt meist einen grösseren und einen kleineren seitenast. Alle stacheln und grösseren äste sind dreikantig. Masse für ein mittelgrosses, wohl entwickeltes exemplar (nach Jørgensen): Oberer unverzweigter teil der basalstacheln 0.018mm lang, 0.004mm breit; die grössten zweigdornen 0.115-0.130mm lang. Die Jugendformen von Plagiacantha arachnoides, von Jørgensen als forma minor bezeichnet, unterscheiden sich von den erwachsenen durch kürzere und dünnere stacheln, deren jeder einen kranz von drei ästen, aber keine seitendornen und brückenbalken aufweist. Alle möglichen übergänge zu den erwachsenen sind natürlich vorhanden.


Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): Extant. Data source: Lazarus et al. 2015 - "R age group"
First occurrence (base): within Quaternary Period (0.00-2.59Ma, base in Gelasian stage). Data source: Lazarus et al. 2015 - "R age group"

Plot of occurrence data:

References:

Bjørklund, K. R. & Kruglikova, S. B. (2003). Polycystine radiolarians in surface sediments in the Arctic Ocean basins and marginal seas. Marine Micropaleontology. 49(3): 231-273. gs

Claparède, E. & Lachmann, J. (1858). Echinocystida. . 1: 431-434 and 458-463. gs

Claparede, E (1855). Uber die Lebenserscheinugen und insbesondere Bewegungserscheinungen der Acanthometren. Monatsberichte der Koniglichen Preussische Akademie der Wissenschaften zu Berlin. 1855: 674-676. gs

Cleve, P. T. (1899a). Plankton collected by the Swedish expedition to Spitzbergen in 1898. Kongliga Svenska Vetenskaps-Akademiens Handlingar. 32(3): 1-51. gs

Cortese, G., Bjørklund, K. R. & Dolven, J. K. (2003). Polycystine radiolarians in the Greenland-Iceland-Norwegian Seas: species and assemblage distribution. Sarsia. 88(1): 65-88. gs

Haeckel, E (1887). Report on the Radiolaria collected by H.M.S. Challenger during the years 1873-1876. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-1876. 18: 1-1803. gs O

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

Schröder, O (1914). Die nordischen Nassellarian. In, Brandt, K. & Apstein, C. (eds) Nordisches Plankton. Lipsius und Tischer, Kiel and Leipzig 67-146. gs O

Swanberg, N. R. & Bjørklund, K. R. (1987a). Radiolaria in the plankton of some fjords in western and northern Norway: the distribution of species. Sarsia. 72(3-4): 231-244. gs

Missing or ambiguous references: Cleve 1899;


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Plagiacantha arachnoides compiled by the radiolaria@mikrotax project team viewed: 28-2-2024

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