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Siphocampe arachnea (Ehrenberg, 1838)

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Eucyrtidium lineatum, γ arachneum: loricae lineis longitudinalibus aliis lineolis transversis in opus reticulatum contextis. E. fundo 10998' groenlandico.
Ehrenberg 1861
Shell small, bullet-shaped, consisting of cepalis, thorax and abdomen; abdomen usually marked by a series of five to seven rounded constrictions alternating with one transverse row of subcircular pores. There is a well-developed surface network or sculpture of both longitudinal and transverse ridges, which is the most distinctive characteristic of the species. Cephalis spherical with a few irregularly scattered pores; no apical horn; vertical tube short, cylindrical, directed obliquely upward at about 45°. Collar stricture indistinct. Thorax somewhat inflated with two (according to Petrushevskaya, 1967, three or four) transverse rows of subcircular pores. Lumbar stricture not well developed. Post-thoracic segmentations usually marked by indentations, more pronounced proximally than distally, between pore rows. Termination ragged, or there may be a poreless peristome with a ragged margin, as tough it is broken along a pore row.
Dimensions (based on 17 specimens): Total length 110-160µm; maximum breadth 47-60µm.
Nigrini 1977











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