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POGONOPHORA Incertae ordinis et familiae

Beklemishevites grandis Mierzejewski, 1986

Beklemishevites grandis is hitherto known only from
an erratic boulder of the Ordovician age, found in
Pleistocene glacial deposits of Poland near Mochty
(Valley of the Vistula River). The holotype represents a
fragment of unflattened tube, 18 mm long and 0.4 mm in
diameter. The remaining fragments vary from 1 to 8 mm in
length and 0.3 to 0.4 mm in diameter. Some tubes are
strongly flattened. Tubes black, with mat, rough and
unornamented outer, and smooth and shiny inner surface.
   
   SEM studies show laminar structure of the wall.
However, the micrographs obtained did not give any
additional information on the nature of the laminae.
Electron micrographs obtained with the use of TEM clerly
show that the laminae are built of characteristic parabolic
fibres, forming the so-called "Bouligand pattern". This
suggests that the tube of B. grandis was built of
chitin-protein complex.
 
   The total tube length of B. grandis remains unknown
but it may be assumed that they were about dozen or so
cm long. The Recent species Siboglinum cinctum Ivanov
is characterized by tubes of a similar diameter, 0.3-0.4
mm, and up to 15 cm long.



DIAGNOSIS: Straight thick-walled tubes, circular in
cross-section, 0.3-0.4 mm in diameter. External surface
unornamented. Tube wall with laminar structure, displaying
typical  "Bouligand pattern".

SEM micrograph displaying lamellar structure
of the living tube of Beklemishevites grandis.
                                   From P. Mierzejewski.

A "Bouligand pattern" made of chitin-protein
complex in the living tube of Beklemishevites
grandis, as seen in transmission electron
microscope.
                                    From P. Mierzejewski .