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Clathrospyris sandellae
Goll and Björklund, 1978
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Description - Add description
Sagittal ring tall, subpolygonal (Plate 2, Figure 3; Plate3, Figure 5); 66 to 80 μm high; 50 to 65 μm thick; joined directly to front, top and back of lattice shell. Front of sagittal ring bears a longitudinal external ridge (Plate 2, Figures 8 and 11). Broad vertical spine arises at approximate midpoint of sagittal ring, located in middle of lowest pair of sagittal lattice pores (Plate 3, Figures 4 and 11). Simple apical spine short, slender, inconspicuous on most specimens. Small axobate faintly visible under bright-field illunination (Plate 2, Figures 6 and 9). Primary lateral bars joined to basal ring. Basal ring inflated, subcircular, strongly constricted sagitally; 87 to 104 μm wide; 60 to 95 μm thick; joined directly to front and back of sagittal ring; and encloses two pairs of basal pores, of which the back is pair is equal in size or larger than the front pair (Plate 2, Figure 6 and 9; Plate 3, Figure 8). Lattice shell 75 to 104 μm high, 95 to 140 μm wide, and extneds below basal ring as short "skirt" of lattice joining the basal spines in an irregular trellis (Plate 2, Figue 11; Plate 3, Figures 1 and 11). This basal lattice extension is very delicate and incompletely preserved on many specimens, but serrated margins on the basal ring and basal spines indicate its original presence (Plate 3, Figure 2). A delicate plate of lattice surrounds the lower front of the sagittal ring of some specimens (Plate 2, Figure 5; Plate 3, Figures 2 and 9) in a manner similar to that described for Corythospyris jubata n. sp. Constriction of lattice shell by sagittal ring varies from slight on some specimens (Plate 3, Figure 10) to quite pronounced on others (Plate 2, Figue 4). Rare specimens have a loosely trellised plate of lattice extending over the top of the sagittal ring and joined to the apical spine (Plate 2, Figure 8). Basal spines five to nine in number, originate at basal ring, project obliquely downward, extend 25 to 40 μm below lattice "skirt," are subcircular in cross-section, of approximately equal length, and taper to a simple point. Lattice bars massive, tuberculate, frame subcircular pores 5 to 22 μm in diameter on most specimens (Plate 3, Figure 11). Rare individuals have thin smooth lattice bars (Plate 2, Figure 10). Pores on lateral portions of lattice shell display no discernible organization. Six symmetrical pairs of large lattice pores occupy regular positions around the sagittal ring.
Diagnosis:
A species of Clathrospyris characterized by the presence of a massive tuberculate lattice shell which extends below the sagittal ring.
Holotype:
Plate 3, Figures 6-11; locality: 338-10-2, 60-62 cm; repository: U. S. National Museum, Washington, D. C.
Remarks:
Clathrospyris sandellae bears a strong resemblance to Triceraspyris antarctica (Haecker) Riedel, 1959. A manuscript is now in progress which deals with the taxonomic status of the latter species. The major difference between these two high latitude morphs is the arrangement by which the lattice shell joins to the sagittal ring. Unlike C. sandellae, Triceraspyris antarctica displays poor organization in the positions and number of lattice bar pairs joined to the sagittal ring; the number varies from 9 to 20. Consequently, the sizes of the intervening sagittal lattice pores are quite small and approximately equidimensional to other lattice pores. Clathrospyris sandellae has only five pairs of lattice bars joined to the sagittal ring, and intervening sagittal lattice pores are quite large in comparison to those of T. antarctica.
Occurrence:
Clathrospyris sandellae is regarded as an indigenous Arctic or Subarctic trissocyclid. Range data for this species are identical to the
range for Clathrospyris at Site 338.
| | Goll and Björklund 1978 |
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