Cavinula vincentii Antoniades & Hamilton
Cavinula vincentii Antoniades & Hamilton (Figs 74–81, 172–180) Valves elliptic with broadly rounded ends. Valve length 11–13.5 µm, width 8–10 µm. Striae radiate at center, more strongly radiate towards ends, 22–26 in 10 µm. Striae uniseriate with elliptical to rounded areolae discernable in LM....
| Main Authors: | , , , |
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| Format: | Other/Unknown Material |
| Language: | unknown |
| Published: |
2014
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| Subjects: | |
| Online Access: | https://zenodo.org/record/5149495 https://doi.org/10.5281/zenodo.5149495 |
| Summary: | Cavinula vincentii Antoniades & Hamilton (Figs 74–81, 172–180) Valves elliptic with broadly rounded ends. Valve length 11–13.5 µm, width 8–10 µm. Striae radiate at center, more strongly radiate towards ends, 22–26 in 10 µm. Striae uniseriate with elliptical to rounded areolae discernable in LM. Axial area narrow, linear; central area small, elliptical or almost round, to asymmetrically elongated. Short and long alternating striae surround the central area. Short striae along valve length, extend onto valve mantle. Internally striae between thickened costae and areolae covered with a hymen. Externally, raphe filiform. Proximal raphe fissures expanded pores, slightly unilaterally bent; distal raphe fissures small pores, terminating on valve face. Internally, raphe linear, positioned on thickened sternum. Terminal raphe fissures with a helictoglossa, not present on proximal raphe ends. Adjacent to distal raphe ends one enlarged, transversally elongated pore-like fissure, externally separated with a small ridge-like structure from areolae. Copulae open bands, with one row of pores, two or more at each valve. Type: –– White Pond, Alert, Ellesmere Island, Nunavut, Canada. Antoniades et al. 2009, figs 7–9 (holotype). Here presented in Figs 172–180 (type material). Observations:— Cavinula vincentii was described from Ellesmere Island, Canada. The taxon resembles the elliptical forms of C. pseudoscutiformis (Figs 44–53), but it is clearly distinguished by the valve outline, which is more elliptical, has a larger central area and the general morphology of the raphe. The main morphological character which separates C. vincentii from C. pseudoscutiformis and also the other taxa belonging to the genus Cavinula is the presence of the pore-like fissures at the valve apices. Based on SEM photomicrographs one other taxon, C. scutiformis has distinct pore-like fissures at the valve apices. Additionally, a specimen identified by (Krammer & Lange-Bertalot, 1986, fig. 59: 12) as C. pseudoscutiformis from Europe appears to be ... |
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