The silicoflagellate genus Distephanus (Distephanopsis)

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1 The silicoflagellate genus Distephanus (Distephanopsis)
Robert Baldwin University Day April 14, 2010

2 What is a silicoflagellate?
“Silicoflagellates are protists and claimed both by zoologists (as protozoans) and botanists (as algae). However, due to their autotrophic phytoplanktonic nature it is more logical to regard them as planktonic algae.” “The silicoflagellates are minute (20−50 µm, rarely up to 100 µm), unicellar, marine flagellates with a siliceous skeleton.” Bilal U. Haq et al., 1978 “The silicoflagellates are a group of planktonic protists, exclusively marine, that contain chromatophores for photosynthesis. In that respect they are like other ‘algae’. They possess a single flagellum, presumably to maintain proper orientation to the sun for maximum efficiency in photosynthetic production. Unlike other “algae”, however, they also possess pseudopodia – a fact that led several early scholars to classify them as ‘animals’.” Richard T. Carter, 2008

3 How silicoflagellates are used
Silicoflagellates are silica-secreting marine microplankton. “Recent revival of interest in the history of ocean basins and paleoclimates has enhanced their importance in paleooceanographic interpretations, especially in those areas where calcareous microfossils are either relatively scarce or completely lacking (e.g., in higher latitudes and deeper waters).” Bilal U. Haq et al., 1978 The carbonate compensation depth The reason why silica fossils are useful in deeper waters is because calcareous fossils dissolve below the calcite compensation depth. The calcite compensation depth (CCD), at the present time, is about 4200 to 4500 meters and can be 5000 meters deep in some places at the present time. It has not always been the same in the past. (Wikipedia)

4 Skeletal Terminology Figure 1. Maximum length = 65 microns.
Richard T. Carter, 2007

5 Richard T. Carter, 2007

6 Silicoflagellate descriptive terminology
McCartney et al., 1990

7 Distephanus speculum has a hollow skeleton
Y. T. Mandra

8 Distephanus speculum with a double skeleton
J. A. Barron

9 McCartney et al., 1990

10 McCartney et al., 1990

11 McCartney et al., 1990

12 Pseudofibula Plexus map McCartney et al., 1993

13 pseudofibulid morphologies
McCartney et al., 1990

14 The second column shows the minimum-distance configuration that connects all points (from Almgren and Taylor, 1976; Isenberg, 1976). McCartney et al., 1990

15 Scanning electron micrographs of specimens of the pseddofibula plexus from Leg 113, 100x.
McCartney et al., 1990

16 Pseudofibula Plexus of Distephanus speculum speculum from ODP Leg 113
McCartney et al., 1990

17 Richard T. Carter, 2008

18 Richard T. Carter, 2008

19 Distribution of Dictyocha and Distephanus
McCartney, 1995 Distephanus

20 Multiwindowed morphologies and some many sided types from ODP Leg 113
McCartney et al., 1990

21 Cretaceous genera McCartney et al., 1990

22 Wide band indicates relative abundance > 50 %.
Narrow band denotes relative abundance = 10 %. Line indicates a regular presence. Small numbers refer to DSDP Leg. McCartney, 1987

23 Richard T. Carter, 2008

24 Richard T. Carter, 2007

25 Corbisema triacantha (Ehrenberg)
McCartney et al., 1990

26 Richard T. Carter, 2007

27 Richard T. Carter, 2008

28 Richard T. Carter, 2007

29 Richard T. Carter, 2008

30 Richard T. Carter, 2007

31 Richard T. Carter, 2008

32 Richard T. Carter, 2007

33 Dictyocha calida Poelchau,
abapical view McCartney et al., 1990

34 Richard T. Carter, 2008

35 Richard T. Carter, 2007

36 Richard T. Carter, 2008

37 Richard T. Carter, 2007

38 Richard T. Carter, 2007

39 Richard T. Carter, 2007

40 Distephanus bolivensis
McCartney et al., 1990

41 Distephanus polyactis
1973

42 Cannopilus hemisphaericus
A Bachmann et al., 1963

43 Cannopilus hemisphaericus
A Bachmann et al., 1963

44 Richard T. Carter, 2008

45 Cannopilus sphaericus
A Bachmann et al, 1963

46 Cannopilus picassori A Bachmann et al., 1963

47 Cannopilus picassori A Bachmann et al., 1963

48 References: Silicoflagellate: Distephanus speculum, showing hollow skeleton. Upper Miocene near San Felipe, Baja California. Upper specimen is about 60 microns from spine tip to tip. Scanning electron micrograph. From Y. T. Mandra and H. Mandra, Occasional Papers of the California Academy of Sciences, no. 99. Used with the permission of Y. T. Mandra, San Francisco State University. Silicoflagellate: Distephanus speculum with a double skeleton. Late Miocene. Lompoc, California. Length is 45 microns. Courtesy of J. A. Barron, U. S. G. S. Carbonate compensation depth (Wikipedia) This page was last modified on 21 February 2010